Case Studies of Two Classical Imprinting Growth Disorders: Silver-Russell and Beckwith-Wiedemann Syndromes.

The genetic influences on human growth are being increasingly deciphered. Silver-Russell and Beckwith-Wiedemann syndromes (SRS; BWS) are two relatively common genetic syndromes with under- and overgrowth-related issues being the reason for referral. Aberration in genomic imprinting is the underlying genetic pathomechanism behind these syndromes. Herein, we described a series of children with these two growth disorders and give an orientation to the reader of the concept of imprinting as well as the genetic testing strategy and counseling to be offered in these syndromes.

Severity Scoring Cutoff for MLPA and Its Diagnostic Yield in 332 North Indian Children with Developmental Delay.

Chromosomal aberrations/rearrangements are the most common cause of intellectual disability (ID), developmental delay (DD), and congenital malformations. Traditionally, karyotyping has been the investigation of choice in such cases, with the advantage of being cheap and easily accessible, but with the caveat of the inability to detect copy number variations of sizes less than 5 Mb. Chromosomal microarray can solve this problem, but again the problems of expense and poor availability are major challenges in developing countries. The purpose of this study is to find the utility of multiplex ligation-dependent probe amplification (MLPA) as a middle ground, in a resource-limited setting. We also attempted to establish an optimum cutoff for the de Vries score, to enable physicians to decide between these tests on a case-to-case basis, using only clinical data. A total of 332 children with DD/ID with or without facial dysmorphism and congenital malformations were studied by MLPA probe sets P245. Assessment of clinical variables concerning birth history, facial dysmorphism, congenital malformations, and family history was done. We also scored the de Vries scoring for all the patients to find a suitable cutoff for MLPA screening. In our study, the overall detection rate of MLPA was 13.5% (45/332). The majority of patients were DiGeorge's syndrome with probe deletion in 22q11.21 in 3.3% (11/332) followed by 15q11.2 del in 3.6% (12/332, split between Angelman's and Prader-Willi's syndromes). Also, 3.0% (10/332) of patients were positive for Williams-Beuren's syndrome 7q11.23, 1.8% (6/332) for Wolf--Hirschhorn's syndrome 4p16.3, 1.2% (4/332) for 1p36 deletion, and 1% for each trichorhinophalangeal syndrome type I 8q23.3 duplication syndrome and cri du chat syndrome. The optimum cutoff of de Vries score for MLPA testing in children with ID and/or dysmorphism came out to be 2.5 (rounded off to 3) with a sensitivity of 82.2% and specificity of 66.7%. This is the largest study from India for the detection of chromosomal aberrations using MLPA common microdeletion kit P245. Our study suggests that de Vries score with a cutoff of 3 or more can be used to offer MLPA as the first tier test for patients with unexplained ID, with or without facial dysmorphism and congenital malformations.

Novel Compound Heterozygous Mutations of LIG4 Gene in an Indian LIG4 Syndrome Patient with Severe Microcephaly: Case Report, In-silico Analysis and Systematic Review.

BACKGROUND: LIG4 syndrome, characterized by immunodeficiency, sensitivity to ionizing radiations, intrauterine growth retardation, postnatal growth retardation, and microcephaly, is a rare genetic disorder caused by pathogenic variants of the LIG4 gene. Few patients are presented with no immune dysregulation as well. CASE STUDY: We present here a male child of 2 years and 4 months of age with severe microcephaly and short stature. His birth weight was 1.9 Kg, and his current height, weight, and head circumference are 83.2 cm (z score = -2.37), 9.5 Kg (z score = -2.76), and 36 cm (z score = -9.24), respectively. Possible causative pathogenic compound heterozygous variants of the LIG4 gene, which were inherited from the parents, were identified by whole exome sequencing of the DNA of the patient and his parents. A systematic review of the literature is also performed to summarize the patients of LIG4 syndrome reported worldwide and summarize the associated genetic mutations of the LIG4 gene. Compound heterozygous variants (c.597_600delTCAG/ c.342del) of LIG4 gene were identified. The parents were found to be heterozygous carriers of one variant each. CONCLUSION: The in-silico analysis of identified variants explains their effect on the structure and function of the LIG4 protein hence explaining the genotype-phenotype correlation.

Estrogen Receptor 1 Gene Polymorphism and its Association with Idiopathic Short Stature in North Indian Population.

Background: In the hypothalamic-pituitary-gonadotrophin (HPG) axis, estrogen plays a key role in the bone maturation regulation and growth plates closure. This study was designed to explore the link between single nucleotide polymorphisms (SNPs) in estrogen receptor 1 (ESR1) gene with idiopathic short stature (ISS) susceptibility in the North Indian population. Methods: Four SNPs of the ESR1 gene (rs543650, rs6557177, rs2234693 and rs9340799) were genotyped by Sanger sequencing in 52 ISS patients and 68 controls. Linkage disequilibrium (LD) and haplotyping were done by SNPstat and SHESISplus softwares. Extent of LD was determined by calculating D' and r2 values in SNPs paired combinations. Results: A significant positive association was found between rs6557177 and rs543650 genotype and ISS susceptibility as compared to controls. The frequencies of the rs6557177 CC genotype (p=0.030; OR=0.13; 95% CI:0.01-1.10) and rs543650 genotype TT (p =0.043; OR=0.29; 95% CI: 0.09-0.92) were observed to be increased in ISS group as compared with the control group. However, no significant correlation was observed between clinical parameters of patients and these SNPs. rs543650 shown strong LD with rs2234693 and rs9340799, similarly rs2234693 and rs9340799. Conclusion: Our study showed that CC genotype at rs6557177 and TT genotype of rs543650 of ESR1 constitutes risk factor for developing ISS in North Indian children. In the future, these findings may lead to a better understanding of the SNPs associated with ISS susceptibility.

Chromosomal Duplication Syndromes: A Case Series.

Chromosomal deletion and duplication syndromes can lead to intellectual disability, autism, microcephaly, and poor growth. Usually manifestations of duplication syndromes are milder than that of the deletion syndromes. With the availability of tests for analysis of copy number variants, it is possible to identify the deletion and duplication syndromes with greater ease. We report 32 cases of chromosomal duplication syndromes, identified in children presenting with developmental delay, intellectual disability, or microcephaly and/or additional features, at a tertiary care center on karyotyping or microarray analysis. Seven were isolated duplications, and one child had an additional smaller pathogenic deletion. Thus, duplication syndromes can have milder presentations with spectrum of dysmorphism, behavioral problems, and intellectual disability, but it is possible to diagnose easily with latest emerging high-throughput technologies.

Lysosomal storage disorders identified in adult population from India: Experience of a tertiary genetic centre and review of literature.

Lysosomal storage disorders (LSDs) in adults have milder phenotype and variable age at presentation. Several studies have described the phenotype, genotype and treatment outcomes for adult-onset LSDs like Gaucher, Fabry, Pompe disease and others. We describe the first systematic study on the occurrence of LSDs in an adult population from India. It describes, the key clinical signs seen in these patients and those from literature review that can aid in early detection. Of 2102 biochemically diagnosed LSDs cases, 32 adult patients were identified with LSDs. Based on the clinical suspicion, screening test and enzyme study was carried out. Twenty-two patients were subjected to a genetic study to identify the causative variant in a respective gene. Of the 32 adult patients, we observed a maximum percentage of 37.5% (n = 12) cases with Gaucher disease, followed by 13% (n = 4) with Fabry disease. We found 10% of cases with MPS IVA and MPS I, and 9% cases with Pompe. Single case of adult mucolipidosis III and two cases each of Type 1 Sialidosis, Niemann-Pick disease B and metachromatic leukodystrophy were identified. We observed two common variants p.Leu483Pro and p.Ala487Thr in the GBA1 gene in 23% of Indian patients with adult Gaucher disease. No common variants were observed in other aforementioned LSDs. Study identified 50% of Fabry patients and 4% of Gaucher patients diagnosed at our centre to be adults. The prevalence of adult Pompe patients was low (3.4%) as compared to 80% reported in the Caucasian population. Adult LSDs such as, MPS III, GM1/GM2 gangliosidosis and Krabbe disease were not identified in our cohort.

Growth charts for weight and height of Indian children with Down syndrome.

Age and gender specific growth charts for Indian children with Down syndrome (DS) based on longitudinal data have not been published. To establish percentile growth charts for DS children inhabiting northwestern parts of India, body weight and length/height of 1125 (Male: 752, Female: 373) children with DS aged <1 month to 10 years, enrolled from the "Genetics Clinic" were measured at half yearly age intervals in the "Growth Clinic" of the Institute from August 1994 to November 2018. A total of 2089 observations were made on these children using standardized anthropometric techniques and instruments following a prospective mixed-longitudinal growth research design. Using the LMS method, age and sex-specific percentile growth charts (<1 month to 10 years) for weight, and length/ height were generated. Unpaired t-test was used to compare mean growth attainments of study children with those of DS patients representing other population groups as well as their normal Multicentre Growth Reference Study (MGRS and Indian Academy of Pediatrics (IAP) counterparts. The 50th percentile growth curves for both weight and length/height of Indian children with DS demonstrated a regular increase. As compared to their normal MGRS and Indian (IAP) counterparts, the children with DS had lower weight and height attainments. The boys and girls with Down syndrome showed short stature (height < 3rd centile) from the age of 1 year till 10 years and also became underweight beyond 5 years. As compared to their normal counterparts, children with Down syndrome exhibited compromised auxological attainments. The use of growth charts presented herein may be used to compare and monitor growth and nutritional status of Indian children with Down syndrome.

Multi-gene panel sequencing in highly consanguineous families and patients with congenital forms of skeletal dysplasias.

Skeletal dysplasias (SKDs) are a heterogeneous group of more than 750 genetic disorders characterized by abnormal development, growth, and maintenance of bones or cartilage in the human skeleton. SKDs are often caused by variants in early patterning genes and in many cases part of multiple malformation syndromes and occur in combination with non-skeletal phenotypes. The aim of this study was to investigate the underlying genetic cause of congenital SKDs in highly consanguineous Pakistani families, as well as in sporadic and familial SKD cases from India using multigene panel sequencing analysis. Therefore, we performed panel sequencing of 386 bone-related genes in 7 highly consanguineous families from Pakistan and 27 cases from India affected with SKDs. In the highly consanguineous families, we were able to identify the underlying genetic cause in five out of seven families, resulting in a diagnostic yield of 71%. Whereas, in the sporadic and familial SKD cases, we identified 12 causative variants, corresponding to a diagnostic yield of 44%. The genetic heterogeneity in our cohorts was very high and we were able to detect various types of variants, including missense, nonsense, and frameshift variants, across multiple genes known to cause different types of SKDs. In conclusion, panel sequencing proved to be a highly effective way to decipher the genetic basis of SKDs in highly consanguineous families as well as sporadic and or familial cases from South Asia. Furthermore, our findings expand the allelic spectrum of skeletal dysplasias.

Neurofibromatosis type 1: Clinical characteristics and mutation spectrum in a North Indian cohort.

Background: Neurofibromatosis type 1 (NF1) is a unique, highly penetrant neuro-cutaneous disorder with a wide range of manifestations. Though the clinical diagnosis of NF1 is straight forward, there can be other disorders which mimic NF1, especially its cutaneous features. Here we describe the clinical and mutation spectrum of a series of individuals whose primary diagnosis was NF1 or NF1 related disorders. Methods: We have screened 29 unrelated individuals who fulfilled the clinical criteria of NF1. Whole exome sequencing (WES) was done in all individuals except one with suspected microdeletion syndrome with NF1 in whom Cytogenetic microarray (CMA) was done. Results: Out of 29 suspected patients, 25 had germline pathogenic/likely pathogenic variants involving NF1 gene. Five novel and 20 known variants in coding and non-coding regions were identified, among them 7 variants were deletions (28%), 7 nonsense (28%), 3 splice-site (12%), 4 missense (16%), 2 duplications (8%) and 2 (8%) were contiguous deletions. In those where NF1 variants were not detected, 3 had neurofibromatosis type 2 (NF2) and 1 rare autosomal recessive form of Elher Danlos syndrome. Conclusion: We hereby present the wide range of manifestations in different age groups and the mutation spectrum ranging from small scale variants to contiguous gene deletion syndromes involving NF1 gene. We highlight the usefulness of molecular testing and its importance in tumor surveillance and genetic counseling in this disorder.

SHOX Variations in Idiopathic Short Stature in North India and a Review of Cases from Asian Countries

Objective: Short stature homeobox (SHOX) haploinsufficiency underlies idiopathic short stature (ISS) and Leri-Weill dyschondrosteosis. The worldwide prevalence of SHOX variations in ISS varies from 2.5% to 15.0%. The aim of this study was to assess the implication of SHOX variation in ISS in North Indians and compare this with other cases of SHOX variations from Asian population. Methods: SHOX gene analysis was carried out by multiplex ligation-dependent probe amplification followed by Sanger sequencing in 54 patients with variable phenotypes. Comparison with other reports in a meta-analysis comprising the current study and 11 previous studies (n=979) was performed. Results: SHOX analysis resulted in 12.9% positivity (7.4% deletions and 5.5% duplications). SHOX association was seen significantly related to gender, with predominance in females (p=0.047). Short arms and forearms were the only significantly associated trait seen in 51.9% of children. The overall prevalence of SHOX variation was 15.2% in Asians with ISS. No significant difference was found in geographical region-specific analysis. Conclusion: This study summarises findings from the last decade and provides an updated picture of the prevalence of SHOX variations in Asians, emphasizing their potential as therapeutic targets in ISS patients. Further high quality, large investigations including functional validation is warranted to validate this association.

Identification of genetic alterations in couples and their products of conceptions from recurrent pregnancy loss in North Indian population.

Background: Recurrent pregnancy loss (RPL) is one of the most common pregnancy-related complications, which can be stressful and emotionally draining for a couple. Genetic alterations, which are responsible for RPL, can be present in either of the three genomes: mother, father, or their fetuses. In addition, environmental factors interacting with these three genomes can affect germline cells. With this aim, the present study was conducted to understand the underlying etiology of RPL using Next-generation sequencing (NGS; couple exome and TRIO exomes) in combination with cytogenetic tests [karyotyping and chromosomal microarray (CMA)]. Material & Methods: In present study we recruited 61 couples with RPL (history of ≥ 2 abortions) and 31 products of conceptions (POCs). For all couples karyotyping was done at the time of recruitment, followed by collection of POC samples and parental blood samples. Before processing POC samples for CMA, they were checked for maternal cell contamination (MCC) by QF-PCR. In POC samples with no pathogenic variant, TRIO exome sequencing was done. Further, in case of unavailability of POC sample, couple exome sequencing was done for RPL couples. Results: In six individuals out of 61 couples (5%), abnormality in karyotypes was detected. Among 116 normal karyotypes, there were 11 heteromorphisms (9.5%), for which the couples had to be counselled and reassured. Out of the 31 POCs, 10 were excluded because of MCC (around 30%) and one had major aneuploidy. CMA in POCs identified pathogenic copy number variations (CNVs) in 25% of cases (5/20) and variant of unknown significance (VUS) in 20% of cases (4/20). Autosomal trisomy was the most frequent chromosomal abnormality diagnosed. NGS was performed to establish single-gene causes of RPL. Couple exome sequencing was performed in 20 couples, and 14 were found to be carriers for autosomal recessive conditions. A total of 50 potential disease-causing variants in 40 genes were identified in 33 of 40 individuals (82.5%). Putative causative variants were identified in 37.5% of the TRIO cases (3/8). Mutations in few important genes (SRP54, ERBB4, NEB, ALMS, ALAD, MTHFR, F5, and APOE), which are involved in vital pathways, early embryonic development, and fetal demise, were identified in the POCs. Conclusion: It enhances our understanding of prenatal phenotypes of many Mendelian disorders. These mutated genes may play an auxiliary role in the development of treatment strategies for RPL. There was no correlation of the number of abortions with etiological yield of any technique to detect the cause of RPL. This study shows the utilization of combination of techniques in improving our understanding of the cause of early embryonic lethality in humans.

Growth Pattern and Use of Inter-pupillary Distance in the Detection of Ocular Hypertelorism and Hypotelorism in Indian Down Syndrome Children.

Use of inter-pupillary distance (IPD) for objective evaluation of ocular hypertelorism and hypotelorism is recommended to corroborate diagnosis of syndromic conditions. In view of complete absence of serial data on growth of IPD, this study aims to unfold auxological dynamics of IPD in Down syndrome (DS) children of Indian origin. Inner canthal distance (ICD) and outer canthal distance (OCD) were measured on a total of 1,125 (male: 752, female: 373) DS children, aged 0 to 3 months to 10 years at 6 monthly age intervals using a "Digimatic Sliding Caliper" in the Growth Laboratory/Growth Clinic of the Institute. Using Feingold and Bossert (1974) formula, IPD at each age was calculated from ICD and OCD measured among male and female DS children. IPD, like OCD and ICD increased un-interruptedly among DS children. IPD grew rapidly up to 5 years thereafter, its rapidity became slower. Boys in general, possessed larger IPD than girls, however, gender differences became statistically significant up to first 4 years of life. Our study children possessed significantly smaller IPD as compared with their normal Indian counterparts. None of our DS children depicted ocular hypertelorism while hypotelorism, was noticed amongst 4.9% male and 16.8% female DS patients. Comparison with normative IPD data failed to establish existence of ocular hypertelorism in DS children (<10 years) of north-western Indian origin. Use of age and gender-specific data presented for IPD of DS children may be made for comparative purpose to ascertain inter-population variability.

Genetic Defects in Children with Cardiac Anomalies/Malformations: Noonan and CFC Syndromes.

Cardiac defects presenting in childhood show significant phenotypic and genetic heterogeneity. With availability of advanced genetic technologies, these can be detected early using specialized testing. Prenatal testing is currently feasible with improved ultrasonography and fetal echocardiography. Here, we report two cases of Noonan's and cardiofaciocutaneous syndromes in patients seen in the genetic unit of a tertiary care center presenting with cardiac defect with or without developmental delay, short stature, and dysmorphism. In these conditions, there is also increased risk of malignancy such as juvenile myelomonocytic leukemia. With the advent of next-generation sequencing, definitive diagnosis and counseling is possible in this group of conditions.

Clinical Profile of Indian Children with Down Syndrome.

This retrospective study was performed on 208 patients with Down syndrome (DS) from heterogeneous ethnic population and admitted under Genetics Metabolic Unit. The aim of the study was to look for phenotypic variability and associated complications in children and adolescents with DS. The average age of the evaluated DS patients was 34 months. Cardiac anomalies were found in 128 (62%) of the 208 cases. Among the cardiac disorders, atrial septal defects accounted for 30% of cases. Other complications observed were hypothyroidism and developmental delay in around 31% cases and neonatal cholestasis in 14% cases. Also, we report two cases with Moya-Moya disease and one case with atlanto-axial dislocation.

Clinical and Molecular Heterogeneity of Silver-Russell Syndrome and Therapeutic Challenges: A Systematic Review.

BACKGROUND: Silver-Russell syndrome (SRS) is a developmental disorder involving extreme growth failure, characteristic facial features and underlying genetic heterogeneity. As the clinical heterogeneity of SRS makes diagnosis a challenging task, the worldwide incidence of SRS could vary from 1:30,000 to 1:100,000. Although various chromosomal, genetic, and epigenetic mutations have been linked with SRS, the cause had only been identified in half of the cases. MATERIAL AND METHODS: To have a better understanding of the SRS clinical presentation and mutation/ epimutation responsible for SRS, a systematic review of the literature was carried out using appropriate keywords in various scientific databases (PROSPERO protocol registration CRD42021273211). Clinical features of SRS have been compiled and presented corresponding to the specific genetic subtype. An attempt has been made to understand the recurrence risk and the role of model organisms in understanding the molecular mechanisms of SRS pathology, treatment, and management strategies of the affected patients through the analysis of selected literature. RESULTS: 156 articles were selected to understand the clinical and molecular heterogeneity of SRS. Information about detailed clinical features was available for 228 patients only, and it was observed that body asymmetry and relative macrocephaly were most prevalent in cases with methylation defects of the 11p15 region. In about 38% of cases, methylation defects in ICRs or genomic mutations at the 11p15 region have been implicated. Maternal uniparental disomy of chromosome 7 (mUPD7) accounts for about 7% of SRS cases, and rarely, uniparental disomy of other autosomes (11, 14, 16, and 20 chromosomes) has been documented. Mutation in half of the cases is yet to be identified. Studies involving mice as experimental animals have been helpful in understanding the underlying molecular mechanism. As the clinical presentation of the syndrome varies a lot, treatment needs to be individualized with multidisciplinary effort. CONCLUSION: SRS is a clinically and genetically heterogeneous disorder, with most of the cases being implicated with a mutation in the 11p15 region and maternal disomy of chromosome 7. Recurrence risk varies according to the molecular subtype. Studies with mice as a model organism have been useful in understanding the underlying molecular mechanism leading to the characteristic clinical presentation of the syndrome. Management strategies often need to be individualized due to varied clinical presentations.

A systematic review of the monogenic causes of Non-Syndromic Hearing Loss (NSHL) and discussion of Current Diagnosis and Treatment options.

Hearing impairment is one of the most widespread inheritable sensory disorder affecting at least 1 in every 1000 born. About two-third of hereditary hearing loss (HHL) disorders are non-syndromic. To provide comprehensive update of monogenic causes of non-syndromic hearing loss (NSHL), literature search has been carried out with appropriate keywords in the following databases-PubMed, Google Scholar, Cochrane library, and Science Direct. Out of 2214 papers, 271 papers were shortlisted after applying inclusion and exclusion criterion. Data extracted from selected papers include information about gene name, identified pathogenic variants, ethnicity of the patient, age of onset, gender, title, authors' name, and year of publication. Overall, pathogenic variants in 98 different genes have been associated with NSHL. These genes have important role to play during early embryonic development in ear structure formation and hearing development. Here, we also review briefly the recent information about diagnosis and treatment approaches. Understanding pathogenic genetic variants are helpful in the management of affected and may offer targeted therapies in future.

Chromosome 1p36 Deletion Syndrome: Four Patients with Variable Presentations.

Chromosome 1p36 deletion accounts for around 1% of cases of intellectual disability. The pattern of clinical features includes developmental delay, hypotonia, seizures, short stature, intellectual disability, vision and hearing deficits, congenital heart disease, and renal abnormalities. The size of deletion can be variable. We report four cases of 1p36 deletion syndrome detected in the past 3 years in a genetic clinic. One patient was detected by next-generation sequencing, another by chromosomal microarray, and the remaining two by multiplex ligation-dependent probe amplification. We discuss the variable presentations in the four children. Early diagnosis enables better prognostication and further reproductive planning.

Development of a new screening method for faster kinship analyses in mass disasters: a proof of concept study.

Kinship analysis in forensics is based on the calculation of the respective kinship indices. However, this calculation is only possible when the subject under identification has been associated with a particular population, whose allele frequency data is available for the particular set of STR markers used in the forensic practices. In the case of mass disasters, where a large number of individuals are to be identified, gathering the population frequency data and calculating the kinship indices can be an intricate process which requires a lot of time and huge resources. The new method of allele matching cut off score (AMCOS) developed in this study is based on the allele sharing approach. This approach simply refers to the number of shared alleles (1 or 2) between the two individuals; also known as identical by state (IBS) alleles which might have been inherited from a recent common ancestor in which the alleles are identical by descendent (IBD). In case of mass disasters, this method can be used to narrow down the number of pairs (dead and alive) to be matched for kinship without using the allele frequency data. The results obtained from this method could further be confirmed by LR based method, which uses the allele frequency data of the respective population of the pairs being tested for kinship. AMCOS method has been tested for its sensitivity, specificity and various other statistical parameters and has shown promising values for the same in various types of kinship analyses. This ascertains the authenticity and potential use of this method in forensic practice but only after its validation in a larger sample size. AMCOS method has been tested on siblings and grandparent-grandchildren by using autosomal and X-STR markers both, as the reference samples from the parents cannot always be available for the identification. The present study also compared the results shown by the autosomal and X-STR markers in siblings and grandparent-grandchildren identification, thereby suggesting the use of better set of markers on the basis of obtained values of various statistical parameters.