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1.
N Engl J Med ; 385(14): 1292-1301, 2021 09 30.
Article in English | MEDLINE | ID: mdl-34587386

ABSTRACT

BACKGROUND: Structural birth defects occur in approximately 3% of live births; most such defects lack defined genetic or environmental causes. Despite advances in surgical approaches, pharmacologic prevention remains largely out of reach. METHODS: We queried worldwide databases of 20,248 families that included children with neurodevelopmental disorders and that were enriched for parental consanguinity. Approximately one third of affected children in these families presented with structural birth defects or microcephaly. We performed exome or genome sequencing of samples obtained from the children, their parents, or both to identify genes with biallelic pathogenic or likely pathogenic mutations present in more than one family. After identifying disease-causing variants, we generated two mouse models, each with a pathogenic variant "knocked in," to study mechanisms and test candidate treatments. We administered a small-molecule Wnt agonist to pregnant animals and assessed their offspring. RESULTS: We identified homozygous mutations in WLS, which encodes the Wnt ligand secretion mediator (also known as Wntless or WLS) in 10 affected persons from 5 unrelated families. (The Wnt ligand secretion mediator is essential for the secretion of all Wnt proteins.) Patients had multiorgan defects, including microcephaly and facial dysmorphism as well as foot syndactyly, renal agenesis, alopecia, iris coloboma, and heart defects. The mutations affected WLS protein stability and Wnt signaling. Knock-in mice showed tissue and cell vulnerability consistent with Wnt-signaling intensity and individual and collective functions of Wnts in embryogenesis. Administration of a pharmacologic Wnt agonist partially restored embryonic development. CONCLUSIONS: Genetic variations affecting a central Wnt regulator caused syndromic structural birth defects. Results from mouse models suggest that what we have named Zaki syndrome is a potentially preventable disorder. (Funded by the National Institutes of Health and others.).


Subject(s)
Abnormalities, Multiple/genetics , Congenital Abnormalities/genetics , Genetic Pleiotropy , Intracellular Signaling Peptides and Proteins/genetics , Mutation , Receptors, G-Protein-Coupled/genetics , Wnt Proteins/metabolism , Animals , Disease Models, Animal , Fibroblasts/metabolism , Gene Knock-In Techniques , Genes, Recessive , Humans , Intracellular Signaling Peptides and Proteins/metabolism , Mice , Mice, Transgenic , Pedigree , Phenotype , Receptors, G-Protein-Coupled/metabolism , Syndrome , Wnt Signaling Pathway
2.
Hum Mutat ; 42(4): e15-e61, 2021 04.
Article in English | MEDLINE | ID: mdl-33502066

ABSTRACT

Given the genomic uniqueness, a local data set is most desired for Indians, who are underrepresented in existing public databases. We hypothesize patients with rare monogenic disorders and their family members can provide a reliable source of common variants in the population. Exome sequencing (ES) data from families with rare Mendelian disorders was aggregated from five centers in India. The dataset was refined by excluding related individuals and removing the disease-causing variants (refined cohort). The efficiency of these data sets was assessed in a new set of 50 exomes against gnomAD and GenomeAsia. Our original cohort comprised 1455 individuals from 1203 families. The refined cohort had 836 unrelated individuals that retained 1,251,064 variants with 181,125 population-specific and 489,618 common variants. The allele frequencies from our cohort helped to define 97,609 rare variants in gnomAD and 44,520 rare variants in GenomeAsia as common variants in our population. Our variant dataset provided an additional 1.7% and 0.1% efficiency for prioritizing heterozygous and homozygous variants respectively for rare monogenic disorders. We observed additional 19 genes/human knockouts. We list carrier frequency for 142 recessive disorders. This is a large and useful resource of exonic variants for Indians. Despite limitations, datasets from patients are efficient tools for variant prioritization in a resource-limited setting.


Subject(s)
Exome , Genomics , Exome/genetics , Gene Frequency , Homozygote , Humans , Exome Sequencing
3.
Am J Med Genet A ; 182(5): 953-956, 2020 05.
Article in English | MEDLINE | ID: mdl-32128942

ABSTRACT

Wiedemann-Steiner syndrome (WWS) is a rare disorder characterized by hypotonia, postnatal growth restriction, striking facial dysmorphism, and hirsutism. It is caused by heterozygous pathogenic variants in KMT2A. This gene has an established role in histone methylation, which explains the overlap of WWS with syndromes caused by genes involved in chromatin remodeling. We describe an infant with a novel single base pair deletion in KMT2A with features consistent with WWS, as well as additional features of stenosis of aqueduct of Sylvius and broad toes. The usefulness of Face2Gene as a tool for identification of dysmorphology syndromes is discussed, as in this patient, it suggested WWS as the top candidate disorder. To the best of our knowledge, this is the first patient of WWS reported from India, with a novel genotype and expanded phenotype.


Subject(s)
Abnormalities, Multiple/genetics , Contracture/genetics , Growth Disorders/genetics , Histone-Lysine N-Methyltransferase/genetics , Intellectual Disability/genetics , Microcephaly/genetics , Musculoskeletal Abnormalities/genetics , Myeloid-Lymphoid Leukemia Protein/genetics , Abnormalities, Multiple/diagnosis , Abnormalities, Multiple/epidemiology , Abnormalities, Multiple/physiopathology , Contracture/diagnosis , Contracture/epidemiology , Contracture/physiopathology , Facies , Female , Genotype , Growth Disorders/diagnosis , Growth Disorders/epidemiology , Growth Disorders/physiopathology , Heterozygote , Humans , India/epidemiology , Infant , Intellectual Disability/diagnosis , Intellectual Disability/epidemiology , Intellectual Disability/physiopathology , Male , Microcephaly/diagnosis , Microcephaly/epidemiology , Microcephaly/physiopathology , Musculoskeletal Abnormalities/diagnosis , Musculoskeletal Abnormalities/epidemiology , Musculoskeletal Abnormalities/physiopathology , Mutation/genetics , Phenotype
4.
Ann Hum Genet ; 82(5): 309-317, 2018 09.
Article in English | MEDLINE | ID: mdl-29774539

ABSTRACT

Fructose-1, 6-bisphosphatase deficiency is an autosomal recessive disorder of gluconeogenesis caused by genetic defect in the FBP1 gene. It is characterized by episodic, often life-threatening metabolic acidosis, liver dysfunction, and hyperlactatemia. Without a high index of suspicion, it may remain undiagnosed with devastating consequences. Accurate diagnosis can be achieved either by enzyme assay or gene studies. Enzyme assay requires a liver biopsy and is tedious, invasive, expensive, and not easily available. Therefore, genetic testing is the most appropriate method to confirm the diagnosis. Molecular studies were performed on 18 suspected cases presenting with episodic symptoms. Seven different pathogenic variants were identified. Two common variants were noted in two subpopulations from the Indian subcontinent; p.Glu281Lys (E281K) occurred most frequently (in 10 patients) followed by p.Arg158Trp (R158W, in 4 patients). Molecular analysis confirmed the diagnosis and helped in managing these patients by providing appropriate genetic counseling. In conclusion, genetic studies identified two common variants in the Indian subcontinent, thus simplifying the diagnostic algorithm in this treatable disorder.


Subject(s)
Fructose-1,6-Diphosphatase Deficiency/genetics , Child, Preschool , Female , Fructose-Bisphosphatase/genetics , Genetic Testing , Humans , India , Infant , Infant, Newborn , Male , Polymorphism, Single Nucleotide , Prenatal Diagnosis
5.
Indian J Med Res ; 146(6): 689-699, 2017 Dec.
Article in English | MEDLINE | ID: mdl-29664026

ABSTRACT

Prenatal testing is the best strategy for reducing the burden of genetic disorders and congenital disabilities that cause significant postnatal functional impairment. Universal prenatal screening is advisable for common genetic disorders and congenital anomalies such as Down syndrome, beta-thalassaemia and neural tube defects. Several prenatal-screening tests are now available for Down syndrome, but knowledge about the appropriate timing of the test and the need for pre- and post-test counselling may not be updated among the primary care physicians. There is also a considerable degree of confusion regarding the prenatal screening test to be chosen in each case, due to the availability of a number of new and advanced screening techniques. At present, there is no nation-wide consensus regarding the nature and timing of these prenatal-screening protocols. Due to the absence of any definite guidelines and the additional lacunae in the awareness regarding the appropriate prenatal screening in the country, the optimum benefits of these screening protocols are not reaching the population. This review focuses on the various prenatal screening and diagnostic tests that are available for common genetic conditions and congenital disabilities and attempts to outline the most cost-effective and gestational age-appropriate strategies for prenatal screening for the Indian healthcare set-up. The recommendations suggested would serve as a source guide for formulating prenatal-screening guidelines for reducing the incidence of common genetic disorders and congenital disabilities in India.


Subject(s)
Down Syndrome/diagnosis , Neural Tube Defects/diagnosis , Prenatal Diagnosis/methods , beta-Thalassemia/diagnosis , Cost-Benefit Analysis/economics , Down Syndrome/epidemiology , Down Syndrome/genetics , Female , Genetic Testing/economics , Humans , India/epidemiology , Mass Screening/economics , Neural Tube Defects/epidemiology , Neural Tube Defects/genetics , Pregnancy , Prenatal Diagnosis/economics , beta-Thalassemia/epidemiology , beta-Thalassemia/genetics
6.
Am J Med Genet A ; 170(6): 1510-9, 2016 06.
Article in English | MEDLINE | ID: mdl-27041150

ABSTRACT

Long QT syndrome type 1 (LQT1) is the most common type of all Long QT syndromes (LQTS) and occurs due to mutations in KCNQ1. Biallelic mutations with deafness is called Jervell and Lange-Nielsen syndrome (JLNS) and without deafness is autosomal recessive Romano-Ward syndrome (AR RWS). In this prospective study, we report biallelic mutations in KCNQ1 in Indian patients with LQT1 syndrome. Forty patients with a clinical diagnosis of LQT1 syndrome were referred for molecular testing. Of these, 18 were excluded from the analysis as they did not fulfill the inclusion criteria of broad T wave ECG pattern of the study. Direct sequencing of KCNQ1 was performed in 22 unrelated probands, parents and at-risk family members. Mutations were identified in 17 patients, of which seven had heterozygous mutations and were excluded in this analysis. Biallelic mutations were identified in 10 patients. Five of 10 patients did not have deafness and were categorized as AR RWS, the rest being JLNS. Eight mutations identified in this study have not been reported in the literature and predicted to be pathogenic by in silico analysis. We hypothesize that the homozygous biallelic mutations identified in 67% of families was due to endogamous marriages in the absence of consanguinity. This study presents biallelic gene mutations in KCNQ1 in Asian Indian patients with AR JLNS and RWS. It adds to the scant worldwide literature of mutation studies in AR RWS. © 2016 Wiley Periodicals, Inc.


Subject(s)
Genetic Association Studies , Jervell-Lange Nielsen Syndrome/genetics , KCNQ1 Potassium Channel/genetics , Long QT Syndrome/genetics , Mutation , Phenotype , Romano-Ward Syndrome/genetics , Adolescent , Alleles , Amino Acid Sequence , Child , Child, Preschool , Exons , Female , Humans , India , Infant , Infant, Newborn , Jervell-Lange Nielsen Syndrome/diagnosis , Long QT Syndrome/diagnosis , Male , Romano-Ward Syndrome/diagnosis
7.
Article in English | MEDLINE | ID: mdl-27485560

ABSTRACT

BACKGROUND: Long QT syndromes (LQTS) are characterized by prolonged QTc interval on electrocardiogram (ECG) and manifest with syncope, seizures or sudden cardiac death. Long QT 1-3 constitute about 75% of all inherited LQTS. We classified a cohort of Indian patients for the common LQTS based on T wave morphology and triggering factors to prioritize the gene to be tested. We sought to identify the causative mutations and mutation spectrum, perform genotype-phenotype correlation and screen family members. METHODS: Thirty patients who fulfilled the criteria were enrolled. The most probable candidate gene among KCNQ1, KCNH2 and SCN5A were sequenced. RESULTS: Of the 30 patients, 22 were classified at LQT1, two as LQT2 and six as LQT3. Mutations in KCNQ1 were identified in 17 (77%) of 22 LQT1 patients, KCNH2 mutation in one of two LQT2 and SCN5A mutations in two of six LQT3 patients. We correlated the presence of the specific ECG morphology in all mutation positive cases. Eight mutations in KCNQ1 and one in SCN5A were novel and predicted to be pathogenic by in-silico analysis. Of all parents with heterozygous mutations, 24 (92%) of 26 were asymptomatic. Ten available siblings of nine probands were screened and three were homozygous and symptomatic, five heterozygous and asymptomatic. CONCLUSIONS: This study in a cohort of Asian Indian patients highlights the mutation spectrum of common Long QT syndromes. The clinical utility for prevention of unexplained sudden cardiac deaths is an important sequel to identification of the mutation in at-risk family members.

8.
Hum Mol Genet ; 22(5): 927-40, 2013 Mar 01.
Article in English | MEDLINE | ID: mdl-23184146

ABSTRACT

Glycinergic neurotransmission is a major inhibitory influence in the CNS and its disruption triggers a paediatric and adult startle disorder, hyperekplexia. The postsynaptic α(1)-subunit (GLRA1) of the inhibitory glycine receptor (GlyR) and the cognate presynaptic glycine transporter (SLC6A5/GlyT2) are well-established genes of effect in hyperekplexia. Nevertheless, 52% of cases (117 from 232) remain gene negative and unexplained. Ligand-gated heteropentameric GlyRs form chloride ion channels that contain the α(1) and ß-subunits (GLRB) in a 2α(1):3ß configuration and they form the predominant population of GlyRs in the postnatal and adult human brain, brainstem and spinal cord. We screened GLRB through 117 GLRA1- and SLC6A5-negative hyperekplexia patients using a multiplex-polymerase chain reaction and Sanger sequencing approach. The screening identified recessive and dominant GLRB variants in 12 unrelated hyperekplexia probands. This primarily yielded homozygous null mutations, with nonsense (n = 3), small indel (n = 1), a large 95 kb deletion (n = 1), frameshifts (n = 1) and one recurrent splicing variant found in four cases. A further three cases were found with two homozygous and one dominant GLRB missense mutations. We provide strong evidence for the pathogenicity of GLRB mutations using splicing assays, deletion mapping, cell-surface biotinylation, expression studies and molecular modelling. This study describes the definitive assignment of GLRB as the third major gene for hyperekplexia and impacts on the genetic stratification and biological causation of this neonatal/paediatric disorder. Driven principally by consanguineous homozygosity of GLRB mutations, the study reveals long-term additive phenotypic outcomes for affected cases such as severe apnoea attacks, learning difficulties and developmental delay.


Subject(s)
Epilepsy/genetics , Genetic Diseases, X-Linked/genetics , Muscle Hypertonia/genetics , Receptors, Glycine/genetics , Reflex, Abnormal/genetics , Adolescent , Adult , Amino Acid Sequence , Child , Child, Preschool , Epilepsy/physiopathology , Female , Genetic Diseases, X-Linked/physiopathology , Genetic Predisposition to Disease , Glycine Plasma Membrane Transport Proteins/genetics , Glycine Plasma Membrane Transport Proteins/metabolism , Homozygote , Humans , Male , Molecular Sequence Data , Muscle Hypertonia/physiopathology , Mutation , Pedigree , Protein Conformation , RNA Splice Sites/genetics , Receptors, Glycine/chemistry , Receptors, Glycine/metabolism , Structure-Activity Relationship
9.
Prenat Diagn ; 35(11): 1137-47, 2015 Nov.
Article in English | MEDLINE | ID: mdl-26223439

ABSTRACT

OBJECTIVE: To offer accurate prenatal diagnosis of lysosomal storage disorders in early pregnancy. METHOD: Prenatal enzymatic diagnoses of Gaucher, Fabry, Pompe, Niemann Pick A/B, Tay Sach, Sandoff, GM1, mucoplysaccharidoses, Wolman, Krabbe, Metachromatic leukodystrophy and Batten diseases were made in uncultured chorionic villi samples by fluorometric/spectrophotometric methods. RESULTS: Of 331 prenatal enzymatic diagnosis, 207 fetuses (67%) were normal and 124 (37%) were affected. The interpretation of affected, normal and carrier fetuses was done using their respective reference ranges as well as % enzyme activity of normal mean. The prenatal molecular confirmation was feasible in 43 biochemically diagnosed fetuses. Of the 207 normal reported fetuses, post natal enzymatic confirmation was done in 23 babies, clinical status of another 165 babies was assessed as unaffected via questionnaire on telephone and 19 were lost to follow-up. In affected pregnancies, 123 opted for termination of which 44 were confirmed enzymatically after abortion. A single false positive was determined to be a carrier by prenatal mutation analysis and carried to term. CONCLUSION: We recommend uncultured chorionic villi for reliable prenatal enzymatic diagnosis of various lysosomal storage disorders on account of the low rate of false positive (0.5%) and false negative (2.2%) results.


Subject(s)
Chorionic Villi/enzymology , Lysosomal Storage Diseases/diagnosis , Chorionic Villi Sampling/methods , False Negative Reactions , False Positive Reactions , Female , Humans , Infant, Newborn , Lysosomal Storage Diseases/enzymology , Male , Pregnancy , Pregnancy Trimester, First , Prenatal Diagnosis , Sensitivity and Specificity
10.
Indian J Med Res ; 142(4): 414-25, 2015 Oct.
Article in English | MEDLINE | ID: mdl-26609033

ABSTRACT

BACKGROUND & OBJECTIVES: Mucopolysaccharidosis type VI (MPS VI) is a rare, autosomal recessive lysosomal storage disorder caused by deficient enzymatic activity of N-acetyl galactosamine-4-sulphatase resulting from mutations in the arylsulphatase B (ARSB) gene. The ARSB gene is located on chromosome 5q11-q13 and is composed of eight exons. More than hundred ARSB mutations have been reported so far, but the mutation spectrum of MPS VI in India is still unknown. Hence, the aim of the present study was to identify the mutational spectrum in patients with MPS VI in India and to study the genotype-phenotype association and functional outcomes of these mutations. METHODS: Molecular characterization of the ARSB gene by Sanger sequencing was done for 15 patients (aged 15 months to 11 yr) who were enzymatically confirmed to have MPS VI. Age of onset, clinical progression and enzyme activity levels in each patient were studied to look for genotype-phenotype association. Haplotype analysis performed for unrelated patients with the recurring mutation W450C, was suggestive of a founder effect. Sequence and structural analyses of the ARSB protein using standard software were carried out to determine the impact of detected mutations on the function of the ARSB protein. RESULTS: A total of 12 mutations were identified, of which nine were novel mutations namely, p.D53N, p.L98R, p.Y103SfsX9, p.W353X, p.H393R, p.F166fsX18, p.I220fsX5, p.W450L, and p.W450C, and three were known mutations (p.D54N, p.A237D and p.S320R). The nine novel sequence variants were confirmed not to be polymorphic variants by performing sequencing in 50 unaffected individuals from the same ethnic population. INTERPRETATION & CONCLUSIONS: Nine novel mutations were identified in MPS VI cases from India in the present study. The study also provides some insights into the genotype-phenotype association in MPS VI.


Subject(s)
Genetic Association Studies , Genetic Predisposition to Disease , Mucopolysaccharidosis VI/genetics , N-Acetylgalactosamine-4-Sulfatase/genetics , Child , Child, Preschool , Exons/genetics , Female , Haplotypes , Humans , India , Infant , Male , Mucopolysaccharidosis VI/pathology , Mutation
11.
J Cell Biochem ; 115(3): 566-74, 2014 Mar.
Article in English | MEDLINE | ID: mdl-24130151

ABSTRACT

Phenylketonuria (PKU) is an autosomal recessive metabolic disorder caused by mutational inactivation of the phenylalanine hydroxylase (PAH) gene. Missense mutations are the most common PAH mutation type detected in PKU patients worldwide. We performed PAH mutation analysis in 27 suspected Indian PKU families (including 7 from our previous study) followed by structure and function analysis of specific missense and splice/insertion-deletion/nonsense mutations, respectively. Of the 27 families, disease-causing mutations were detected in 25. A total of 20 different mutations were identified of which 7 "unique" mutations accounted for 13 of 25 mutation positive families. The unique mutations detected exclusively in Indian PKU patients included three recurrent mutations detected in three families each. The 20 mutations included only 5 missense mutations in addition to 5 splice, 4 each nonsense and insertion-deletion mutations, a silent variant in coding region and a 3'UTR mutation. One deletion and two nonsense mutations were characterized to confirm significant reduction in mutant transcript levels possibly through activation of nonsense mediated decay. All missense mutations affected conserved amino acid residues and sequence and structure analysis suggested significant perturbations in the enzyme activity of respective mutant proteins. This is probably the first report of identification of a significantly low proportion of missense PAH mutations from PKU families and together with the presence of a high proportion of splice, insertion-deletion, and nonsense mutations, points to a unique PAH mutation profile in Indian PKU patients.


Subject(s)
Codon, Nonsense/genetics , INDEL Mutation/genetics , Phenylalanine Hydroxylase/genetics , Phenylketonurias/genetics , Alleles , Asian People/genetics , DNA Mutational Analysis , Female , Humans , India , Male , Pedigree , Phenylalanine Hydroxylase/metabolism , Phenylketonurias/etiology , Phenylketonurias/pathology , RNA Splice Sites/genetics
12.
Am J Hum Genet ; 89(6): 745-50, 2011 Dec 09.
Article in English | MEDLINE | ID: mdl-22100072

ABSTRACT

Very-long-chain fatty acids (VLCFAs) play important roles in membrane structure and cellular signaling, and their contribution to human health is increasingly recognized. Fatty acid elongases catalyze the first and rate-limiting step in VLCFA synthesis. Heterozygous mutations in ELOVL4, the gene encoding one of the elongases, are known to cause macular degeneration in humans and retinal abnormalities in mice. However, biallelic ELOVL4 mutations have not been observed in humans, and murine models with homozygous mutations die within hours of birth as a result of a defective epidermal water barrier. Here, we report on two human individuals with recessive ELOVL4 mutations revealed by a combination of autozygome analysis and exome sequencing. These individuals exhibit clinical features of ichthyosis, seizures, mental retardation, and spasticity-a constellation that resembles Sjögren-Larsson syndrome (SLS) but presents a more severe neurologic phenotype. Our findings identify recessive mutations in ELOVL4 as the cause of a neuro-ichthyotic disease and emphasize the importance of VLCFA synthesis in brain and cutaneous development.


Subject(s)
Abnormalities, Multiple/genetics , Eye Proteins/genetics , Genes, Recessive , Ichthyosis/genetics , Intellectual Disability/genetics , Membrane Proteins/genetics , Quadriplegia/genetics , Abnormalities, Multiple/diagnosis , Base Sequence , Child, Preschool , Consanguinity , Developmental Disabilities/genetics , Exome , Fatal Outcome , Fatty Acids/metabolism , Genetic Association Studies , Humans , Ichthyosis/diagnosis , Intellectual Disability/diagnosis , Male , Quadriplegia/diagnosis , Sequence Analysis, DNA
13.
Am J Med Genet A ; 161A(1): 76-81, 2013 Jan.
Article in English | MEDLINE | ID: mdl-23208825

ABSTRACT

Surveys of attitudes of individuals with deafness and their families towards genetic testing or prenatal diagnosis have mostly been carried out in the West. It is expected that the perceptions and attitudes would vary amongst persons of different cultures and economic background. There is little information on the prevailing attitudes for genetic testing and prenatal diagnosis for deafness in developing countries. Therefore, this study evaluates the motivations of Indian people with inherited hearing loss towards such testing. Twenty-eight families with history of congenital hearing loss (23 hearing parents with child/family member with deafness, 4 couples with both partners having deafness and 1 parent and child with deafness) participated in a semi-structured survey investigating their interest, attitudes, and intentions for using genetic and prenatal testing for deafness. Participants opinioned that proper management and care of individuals with deafness were handicapped by limited rehabilitation facilities with significant financial and social burden. Nineteen (68%) opted for genetic testing. Twenty-six (93%) expressed high interest in prenatal diagnosis, while 19 (73%) would consider termination of an affected fetus. Three hearing couples, in whom the causative mutations were identified, opted for prenatal diagnosis. On testing, all the three fetuses were affected and the hearing parents elected to terminate the pregnancies. This study provides an insight into the contrasting perceptions towards hearing disability in India and its influence on the desirability of genetic testing and prenatal diagnosis.


Subject(s)
Culture , Deafness/diagnosis , Genetic Testing , Parents/psychology , Prenatal Diagnosis , Adult , Deafness/genetics , Developing Countries , Female , Genetic Counseling , Health Knowledge, Attitudes, Practice , Humans , India , Male , Middle Aged , Motivation , Mutation , Pedigree , Perception , Pregnancy , Surveys and Questionnaires , Young Adult
14.
Indian J Med Res ; 133: 442-5, 2011 Apr.
Article in English | MEDLINE | ID: mdl-21537100

ABSTRACT

The diagnosis of incontinentia pigmenti (IP) is fairly easy in the presence of classical features, but can be difficult in cases with partial or non-classical features, especially in the parents. The demonstration that the disease is caused by mutations in the NEMO gene, has remarkably improved genetic counselling for this disorder. We present four families of IP in whom molecular studies established an unequivocal diagnosis in the affected daughters, and showed two mothers to be carriers, thus allowing accurate genetic counselling and prenatal diagnosis.


Subject(s)
I-kappa B Kinase/genetics , Incontinentia Pigmenti/diagnosis , Incontinentia Pigmenti/genetics , Mutation/genetics , Pregnancy Complications/genetics , Sequence Deletion/genetics , Child , Child, Preschool , Female , Genetic Counseling , Genetic Services , Humans , Infant , Nuclear Family , Pedigree , Pregnancy , Prenatal Diagnosis
15.
Clin Biochem ; 89: 14-37, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33301762

ABSTRACT

OBJECTIVES: Diagnosis of lysosomal storage disorders (LSDs) remains challenging due to wide clinical, biochemical and molecular heterogeneity. The study applies a combined biochemical and genetic approach to diagnose symptomatic Indian patients of Pompe, Fabry, Gaucher and Hurler disease to generate a comprehensive dataset of pathogenic variants for these disorders. DESIGN & METHODS: Symptomatic patients were biochemically diagnosed by fluorometric methods and molecular confirmation was carried out by gene sequencing. Genetic variants were analyzed according to the ACMG/AMP 2015 variant interpretation guidelines. RESULTS: Amongst the 2181 suspected patients, 285 (13%) were biochemically diagnosed. Of these, 22.5% (64/285) diagnosed with Pompe disease harboured c.1933G>A, c.1A>G, c.1927G>A and c.2783G>C as common and 10 novel pathogenic variants while 7.4% (21/285) patients diagnosed with Fabry disease carried c.851T>C, c.902G>A, c.905A>C and c.1212_1234del as frequent disease-causing variants along with 7 novel pathogenic variants. As many as 48.4% (138/285) patients were diagnosed with Gaucher disease and had c.1448T>C as the most common pathogenic variant followed by c.1342G>C and c.754T>C with 7 previously unreported disease-causing variants and in the 21.7% (62/285) diagnosed cases of Hurler disease, c.1469T>C, c.754delC c.568_581del and c.1898C>T were identified as the most common causative variants along with 21 novel pathogenic variants. CONCLUSION: This comprehensive data set of disease-causing frequent and novel pathogenic variants reported for the first time in such a large patient cohort for each of these four LSDs from the Indian sub-continent, along with their biochemical and clinical spectrum will contribute towards providing definitive diagnosis and treatment, identifying carrier status, as well as in counselling prenatal cases to reduce the morbidity and mortality associated with these disorders.


Subject(s)
Biomarkers/analysis , Fabry Disease/genetics , Gaucher Disease/genetics , Glycogen Storage Disease Type II/genetics , Glycoproteins/genetics , Mucopolysaccharidosis I/genetics , Mutation , Adolescent , Adult , Child , Child, Preschool , Cohort Studies , Fabry Disease/pathology , Female , Gaucher Disease/pathology , Glycogen Storage Disease Type II/pathology , Humans , Infant , Infant, Newborn , Lysosomes , Male , Middle Aged , Mucopolysaccharidosis I/pathology , Young Adult
17.
Indian J Gastroenterol ; 39(6): 599-607, 2020 Dec.
Article in English | MEDLINE | ID: mdl-33191490

ABSTRACT

Incidence of colorectal cancer (CRC) is lower in India than in other parts of the world. Approximately 5% to 10% of CRC is inherited. Hereditary non-polyposis colorectal cancer (HNPCC) syndrome and familial adenomatous polyposis (FAP) syndrome are the two known familial cancer syndromes of gastrointestinal tract, which occur due to inherited genetic predisposition. Not much is known about the molecular profile of families with inherited CRC syndromes seen in Indian population. At our institute, we have been providing genetic testing and counseling service to all the families referred to us with suspicion of inherited cancer predisposition syndrome. We analyzed 36 suspected families at our clinic. Personal and family history of cancer was obtained from the proband and appropriate genetic testing was performed in 19 patients (13 with HNPCC, 5 with FAP, and 1 with Cowden syndrome). We present here our experience and spectrum of pathogenic variants observed in this patient cohort and review on published studies describing molecular profile of Indian patients with CRC syndromes.


Subject(s)
Adenomatous Polyposis Coli Protein/genetics , Colorectal Neoplasms/genetics , DNA-Binding Proteins/genetics , Genetic Predisposition to Disease/genetics , Mismatch Repair Endonuclease PMS2/genetics , MutL Protein Homolog 1/genetics , MutS Homolog 2 Protein/genetics , Mutation/genetics , Asian People/genetics , Cohort Studies , Colorectal Neoplasms/diagnosis , Colorectal Neoplasms/epidemiology , Colorectal Neoplasms/prevention & control , Female , Genetic Counseling , Genetic Testing , Humans , Incidence , India/epidemiology , Male , Syndrome
18.
Eur J Med Genet ; 63(3): 103734, 2020 Mar.
Article in English | MEDLINE | ID: mdl-31349084

ABSTRACT

Autosomal dominant polycystic kidney disease (ADPKD) is caused by pathogenic variants in either PKD1 or PKD2 genes. Disease severity is dependent on various factors including the presence of modifier genes. We describe a family with recurrent foetal presentation of ADPKD due to co-inheritance of pathogenic variants in both PKD1 [c.3860T > C; p.(Leu1287Pro)] and PKD2 [(c.1000C > A; p.(Pro334Thr)] genes. Familial segregation studies revealed the mother and the father to be heterozygous for the same variants in the PKD1 and PKD2 genes, respectively, as found in the foetus. Renal ultrasonography detected evidence of cystic disease in the mother and two of her family members. No cysts were detected in the father, however the paternal grandfather died of renal cystic disease. The absence of disease in the father can be explained by the phenomenon of incomplete penetrance, or Knudson's two-hit hypothesis of cystogenesis in the grandfather. This case underscores the importance of sequencing PKD2 gene even in the presence of a familial PKD1 variant, as well as genetic testing of the cysts for evidence of the second hit.


Subject(s)
Kidney/pathology , Polycystic Kidney, Autosomal Dominant/genetics , TRPP Cation Channels/genetics , Female , Heredity , Heterozygote , Humans , Kidney/physiopathology , Male , Mutation , Pedigree , Phenotype , Polycystic Kidney, Autosomal Dominant/congenital , Polycystic Kidney, Autosomal Dominant/diagnostic imaging , Polycystic Kidney, Autosomal Dominant/physiopathology , Pregnancy , TRPP Cation Channels/chemistry , Ultrasonography , Exome Sequencing
19.
J Clin Lipidol ; 14(1): 35-45, 2020.
Article in English | MEDLINE | ID: mdl-32044282

ABSTRACT

BACKGROUND: Familial hypercholesterolemia (FH), an autosomal codominant disorder characterized by very high low-density lipoprotein cholesterol, is strongly associated with premature coronary artery disease. OBJECTIVES: Molecular landscape of FH in Asian Indians is not well studied, although this ethnic group comprises a large proportion of the world population. Knowledge of mutations in these groups is useful for identifying persons affected with FH, saving their lives, and cascade screening in their relatives. METHODS: Potential cases of FH (n = 100) were identified by criteria adapted for the Indian population from Dutch Lipid Clinic Network criteria. Pathogenic variants were analyzed in LDLR, APOB 100 (exons 26 and 29), PCSK9, and APOE genes using Sanger sequencing and multiplex ligation-dependent probe amplification technique. Cases in whom there were no pathogenic variants were tested by next-generation sequencing using a targeted panel of genes. RESULTS: Thirty-eight pathogenic variants were identified in 47 of 100 unrelated probands. Of these variants, 33 were identified in LDLR, 3 in APOB, and 2 in PCSK9 genes. Ten pathogenic variants were novel. Mutations were detected in 91.4% of those subjects classified as definite, 40% as probable, and in 18.8% as possible FH cases based on modified Dutch Lipid Clinic Network criteria. A likely founder mutation in intron 10 (c.1587-1G>A) of LDLR gene was observed in 6 North Indian families. The conventional pathogenic variants in APOB and PCSK9 genes and those previously reported in LDLR gene among Asian Indians were not detected in this cohort. CONCLUSION: This study demonstrates genetic heterogeneity of FH in India. The variants observed were different from those described in Western populations. Next-generation sequencing technology helped identify new mutations in APOB gene, suggesting that in less-studied populations, it is better to sequence the whole gene rather than test for specific mutations.


Subject(s)
Apolipoprotein B-100/genetics , Apolipoproteins E/genetics , Hyperlipoproteinemia Type II/genetics , Proprotein Convertase 9/genetics , Receptors, LDL/genetics , Adult , Aged , Asian People/genetics , Female , Genetic Heterogeneity , High-Throughput Nucleotide Sequencing , Humans , Hyperlipoproteinemia Type II/epidemiology , Hyperlipoproteinemia Type II/pathology , India/epidemiology , Male , Middle Aged , Mutation/genetics
20.
J Clin Exp Hepatol ; 9(3): 383-406, 2019.
Article in English | MEDLINE | ID: mdl-31360030

ABSTRACT

Liver diseases occurring during pregnancy can be serious and can progress rapidly, affecting outcomes for both the mother and fetus. They are a common cause of concern to an obstetrician and an important reason for referral to a hepatologist, gastroenterologist, or physician. Liver diseases during pregnancy can be divided into disorders unique to pregnancy, those coincidental with pregnancy, and preexisting liver diseases exacerbated by pregnancy. A rapid differential diagnosis between liver diseases related or unrelated to pregnancy is required so that specialist and urgent management of these conditions can be carried out. Specific Indian guidelines for the management of these patients are lacking. The Indian National Association for the Study of the Liver (INASL) in association with the Federation of Obstetric and Gynaecological Societies of India (FOGSI) had set up a taskforce for development of consensus guidelines for management of patients with liver diseases during pregnancy, relevant to India. For development of these guidelines, a two-day roundtable meeting was held on 26-27 May 2018 in New Delhi, to discuss, debate, and finalize the consensus statements. Only those statements that were unanimously approved by most members of the taskforce were accepted. The primary objective of this review is to present the consensus statements approved jointly by the INASL and FOGSI for diagnosing and managing pregnant women with liver diseases. This article provides an overview of liver diseases occurring in pregnancy, an update on the key mechanisms involved in its pathogenesis, and the recommended treatment options.

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