RESUMEN
Androgen insensitivity syndrome (AIS) is a difference of sex development (DSD) characterized by different degrees of undervirilization in individuals with a 46,XY karyotype despite normal to high gonadal testosterone production. Classically, AIS is explained by hemizygous mutations in the X-chromosomal androgen receptor (AR) gene. Nevertheless, the majority of individuals with clinically diagnosed AIS do not carry an AR gene mutation. Here, we present a patient with a 46,XY karyotype, born with undervirilized genitalia, age-appropriate testosterone levels and no uterus, characteristic for AIS. Diagnostic whole exome sequencing (WES) showed a maternally inherited LINE1 (L1) retrotransposon insertion in the 5' untranslated region (5'UTR) of the AR gene. Long-read nanopore sequencing confirmed this as an insertion of a truncated L1 element of ≈ 2.7 kb and showed an increased DNA methylation at the L1 insertion site in patient-derived genital skin fibroblasts (GSFs) compared to healthy controls. The insertion coincided with reduced AR transcript and protein levels in patient-derived GSFs confirming the clinical diagnosis AIS. Our results underline the relevance of retrotransposons in human disease, and expand the growing list of human diseases associated with them.
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Síndrome de Resistencia Androgénica , Metilación de ADN , Epigénesis Genética , Elementos de Nucleótido Esparcido Largo , Receptores Androgénicos , Humanos , Síndrome de Resistencia Androgénica/genética , Síndrome de Resistencia Androgénica/metabolismo , Receptores Androgénicos/genética , Receptores Androgénicos/metabolismo , Masculino , Elementos de Nucleótido Esparcido Largo/genética , Femenino , Secuenciación del Exoma , Transcripción GenéticaRESUMEN
Despite linkage to chromosome 16q in 1996, the mutation causing spinocerebellar ataxia type 4 (SCA4), a late-onset sensory and cerebellar ataxia, remained unknown. Here, using long-read single-strand whole-genome sequencing (LR-GS), we identified a heterozygous GGC-repeat expansion in a large Utah pedigree encoding polyglycine (polyG) in zinc finger homeobox protein 3 (ZFHX3), also known as AT-binding transcription factor 1 (ATBF1). We queried 6,495 genome sequencing datasets and identified the repeat expansion in seven additional pedigrees. Ultrarare DNA variants near the repeat expansion indicate a common distant founder event in Sweden. Intranuclear ZFHX3-p62-ubiquitin aggregates were abundant in SCA4 basis pontis neurons. In fibroblasts and induced pluripotent stem cells, the GGC expansion led to increased ZFHX3 protein levels and abnormal autophagy, which were normalized with small interfering RNA-mediated ZFHX3 knockdown in both cell types. Improving autophagy points to a therapeutic avenue for this novel polyG disease. The coding GGC-repeat expansion in an extremely G+C-rich region was not detectable by short-read whole-exome sequencing, which demonstrates the power of LR-GS for variant discovery.
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Autofagia , Proteínas de Homeodominio , Linaje , Ataxias Espinocerebelosas , Expansión de Repetición de Trinucleótido , Humanos , Autofagia/genética , Expansión de Repetición de Trinucleótido/genética , Proteínas de Homeodominio/genética , Ataxias Espinocerebelosas/genética , Masculino , Femenino , Células Madre Pluripotentes Inducidas/metabolismoRESUMEN
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.
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Consanguinidad , Linaje , Humanos , Masculino , Femenino , Pakistán/epidemiología , India/epidemiología , Osteocondrodisplasias/genética , Osteocondrodisplasias/diagnóstico , Osteocondrodisplasias/patología , Fenotipo , Niño , Mutación , Enfermedades del Desarrollo Óseo/genética , Predisposición Genética a la Enfermedad , Preescolar , Secuenciación de Nucleótidos de Alto Rendimiento , Heterogeneidad GenéticaRESUMEN
Clinical exome and genome sequencing have revolutionized the understanding of human disease genetics. Yet many genes remain functionally uncharacterized, complicating the establishment of causal disease links for genetic variants. While several scoring methods have been devised to prioritize these candidate genes, these methods fall short of capturing the expression heterogeneity across cell subpopulations within tissues. Here, we introduce single-cell tissue-specific gene prioritization using machine learning (STIGMA), an approach that leverages single-cell RNA-seq (scRNA-seq) data to prioritize candidate genes associated with rare congenital diseases. STIGMA prioritizes genes by learning the temporal dynamics of gene expression across cell types during healthy organogenesis. To assess the efficacy of our framework, we applied STIGMA to mouse limb and human fetal heart scRNA-seq datasets. In a cohort of individuals with congenital limb malformation, STIGMA prioritized 469 variants in 345 genes, with UBA2 as a notable example. For congenital heart defects, we detected 34 genes harboring nonsynonymous de novo variants (nsDNVs) in two or more individuals from a set of 7,958 individuals, including the ortholog of Prdm1, which is associated with hypoplastic left ventricle and hypoplastic aortic arch. Overall, our findings demonstrate that STIGMA effectively prioritizes tissue-specific candidate genes by utilizing single-cell transcriptome data. The ability to capture the heterogeneity of gene expression across cell populations makes STIGMA a powerful tool for the discovery of disease-associated genes and facilitates the identification of causal variants underlying human genetic disorders.
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Cardiopatías Congénitas , Transcriptoma , Humanos , Animales , Ratones , Exoma/genética , Cardiopatías Congénitas/genética , Secuenciación del Exoma , Aprendizaje Automático , Análisis de la Célula Individual/métodos , Enzimas Activadoras de Ubiquitina/genéticaRESUMEN
Introduction: Intellectual disability (ID) is a clinically and genetically heterogeneous disorder. It drastically affects the learning capabilities of patients and eventually reduces their IQ level below 70. Methods: The current genetic study ascertained two consanguineous Pakistani families suffering from autosomal recessive intellectual developmental disorder-5 (MRT5). We have used exome sequencing followed by Sanger sequencing to identify the disease-causing variants. Results and discussion: Genetic analysis using whole exome sequencing in these families identified two novel mutations in the NSUN2 (NM_017755.5). Family-A segregated a novel missense variant c.953A>C; p.Tyr318Ser in exon-9 of the NSUN2. The variant substituted an amino acid Tyr318, highly conserved among different animal species and located in the functional domain of NSUN2 known as "SAM-dependent methyltransferase RsmB/NOP2-type". Whereas in family B, we identified a novel splice site variant c.97-1G>C that affects the splice acceptor site of NSUN2. The identified splice variant (c.97-1G>C) was predicted to result in the skipping of exon-2, which would lead to a frameshift followed by a premature stop codon (p. His86Profs*16). Furthermore, it could result in the termination of translation and synthesis of dysfunctional protein, most likely leading to nonsense-mediated decay. The dynamic consequences of NSUN2 missense variant was further explored together with wildtype through molecular dynamic simulations, which uncovered the disruption of NSUN2 function due to a gain in structural flexibility. The present molecular genetic study further extends the mutational spectrum of NSUN2 to be involved in ID and its genetic heterogeneity in the Pakistani population.
RESUMEN
Split-hand/foot malformation (SHFM) shows diverse heterogeneity and manifests with reduced penetrance and variable expressivity. This study investigated the underlying genetic cause of a family segregating SHFM. Exome sequencing followed by Sanger sequencing identified a novel single nucleotide heterozygous variant (NC_000019.9 (NM_005499.3):c.1118del) in UBA2 cosegregating in the family in an autosomal dominant manner. Our findings conclude that reduced penetrance and variable expressivity are the two remarkable and unusual features of SHFM.
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Postaxial polydactyly (PAP) is a common limb malformation that often leads to cosmetic and functional complications. Molecular evaluation of polydactyly can serve as a tool to elucidate genetic and signaling pathways that regulate limb development, specifically, the anterior-posterior specification of the limb. To date, only five genes have been identified for nonsyndromic PAP: FAM92A, GLI1, GLI3, IQCE and ZNF141. In this study, two Pakistani multiplex consanguineous families with autosomal recessive nonsyndromic PAP were clinically and molecularly evaluated. From both pedigrees, a DNA sample from an affected member underwent exome sequencing. In each family, we identified a segregating frameshift (c.591dupA [p.(Q198Tfs*21)]) and nonsense variant (c.2173A > T [p.(K725*)]) in KIAA0825 (also known as C5orf36). Although KIAA0825 encodes a protein of unknown function, it has been demonstrated that its murine ortholog is expressed during limb development. Our data contribute to the establishment of a catalog of genes important in limb patterning, which can aid in diagnosis and obtaining a better understanding of the biology of polydactyly.
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Dedos/anomalías , Genes Recesivos/genética , Predisposición Genética a la Enfermedad/genética , Péptidos y Proteínas de Señalización Intracelular/genética , Mutación , Polidactilia/genética , Dedos del Pie/anomalías , Animales , Consanguinidad , Salud de la Familia , Femenino , Dedos/patología , Genotipo , Humanos , Masculino , Ratones Endogámicos C57BL , Linaje , Fenotipo , Polidactilia/patología , Dedos del Pie/patología , Secuenciación del Exoma/métodosRESUMEN
BACKGROUND: Autosomal recessive congenital ichthyosis (ARCI) is a genetically and phenotypically heterogeneous skin disease, associated with defects in the skin permeability barrier. Several but not all genes with underlying mutations have been identified, but a clear correlation between genetic causes and clinical picture has not been described to date. METHODS: Our study included 19 families from Saudi Arabia, Yemen, and Pakistan. All patients were born to consanguineous parents and diagnosed with ARCI. Mutations were analyzed by homozygosity mapping and direct sequencing. RESULTS: We have detected mutations in all families in five different genes: TGM1, ABCA12, CYP4F22, NIPAL4, and ALOXE3. Five likely pathogenic variants were unknown so far, a splice site and a missense variant in TGM1, a splice site variant in NIPAL4, and missense variants in ABCA12 and CYP4F22. We attributed TGM1 and ABCA12 mutations to the most severe forms of lamellar and erythematous ichthyoses, respectively, regardless of treatment. Other mutations highlighted the presence of a phenotypic spectrum in ARCI. CONCLUSION: Our results contribute to expanding the mutational spectrum of ARCI and revealed new insights into genotype/phenotype correlations. The findings are instrumental for a faster and more precise diagnosis, a better understanding of the pathophysiology, and the definition of targets for more specific therapies for ARCI.
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Eritrodermia Ictiosiforme Congénita/genética , Tasa de Mutación , Transportadoras de Casetes de Unión a ATP/genética , Adolescente , Niño , Sistema Enzimático del Citocromo P-450/genética , Femenino , Genes Recesivos , Genotipo , Humanos , Eritrodermia Ictiosiforme Congénita/epidemiología , Lipooxigenasa/genética , Masculino , Pakistán , Fenotipo , Receptores de Superficie Celular/genética , Arabia Saudita , Transglutaminasas/genética , Adulto JovenRESUMEN
Ciliopathies are disorders of the primary cilium that can affect almost all organs and that are characterized by pleiotropy and extensive intra- and interfamilial phenotypic variability. Accordingly, mutations in the same gene can cause different ciliopathy phenotypes of varying severity. WDR60 encodes a protein thought to play a role in the primary cilium's intraflagellar transport machinery. Mutations in this gene are a rare cause of Jeune asphyxiating thoracic dystrophy (JATD) and short-rib polydactyly syndrome (SRPS). Here we report on a milder and distinct phenotype in a consanguineous Pakistani pedigree with two adolescent sisters affected by retinal degeneration and postaxial polydactyly, but lack of any further skeletal or chondrodysplasia features. By targeted high-throughput sequencing of genes known or suspected to be involved in ciliogenesis, we detected a novel homozygous N-terminal truncating WDR60 mutation (c.44delC/p.Ala15Glufs*90) that co-segregated with the disease in the family. Our finding broadens the spectrum of WDR60-related phenotypes and shows the utility of broad multigene panels during the genetic work-up of patients with ciliopathies.
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Proteínas Adaptadoras Transductoras de Señales/genética , Polidactilia/genética , Degeneración Retiniana/genética , Síndrome de Costilla Pequeña y Polidactilia/genética , Adolescente , Adulto , Cilios/genética , Cilios/patología , Ciliopatías/genética , Ciliopatías/fisiopatología , Síndrome de Ellis-Van Creveld/genética , Síndrome de Ellis-Van Creveld/fisiopatología , Exoma/genética , Femenino , Homocigoto , Humanos , Masculino , Persona de Mediana Edad , Mutación , Linaje , Polidactilia/fisiopatología , Degeneración Retiniana/fisiopatología , Costillas/fisiopatología , Síndrome de Costilla Pequeña y Polidactilia/fisiopatología , Hermanos , Adulto JovenRESUMEN
Developmental and epileptic encephalopathies (DEE) are a heterogeneous group of neurodevelopmental disorders with poor prognosis. Recent discoveries have greatly expanded the repertoire of genes that are mutated in epileptic encephalopathies and DEE, often in a de novo fashion, but in many patients, the disease remains molecularly uncharacterized. Here, we describe a new form of DEE in patients with likely deleterious biallelic variants in PTPN23. The phenotype is characterized by early onset drug-resistant epilepsy, severe and global developmental delay, microcephaly, and sometimes premature death. PTPN23 encodes a tyrosine phosphatase with strong brain expression, and its knockout in mouse is embryonically lethal. Structural modeling supports a deleterious effect of the identified alleles. Our data suggest that PTPN23 mutations cause a rare severe form of autosomal-recessive DEE in humans, a finding that requires confirmation.
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Discapacidades del Desarrollo/genética , Mutación , Proteínas Tirosina Fosfatasas no Receptoras/genética , Espasmos Infantiles/genética , Adulto , Discapacidades del Desarrollo/patología , Femenino , Humanos , Recién Nacido , Masculino , Fenotipo , Conformación Proteica , Proteínas Tirosina Fosfatasas no Receptoras/química , Espasmos Infantiles/patologíaRESUMEN
The CRISPR/Cas technology enables targeted genome editing and the rapid generation of transgenic animal models for the study of human genetic disorders. Here we describe an autosomal recessive human disease in two unrelated families characterized by a split-foot defect, nail abnormalities of the hands, and hearing loss, due to mutations disrupting the SAM domain of the protein kinase ZAK. ZAK is a member of the MAPKKK family with no known role in limb development. We show that Zak is expressed in the developing limbs and that a CRISPR/Cas-mediated knockout of the two Zak isoforms is embryonically lethal in mice. In contrast, a deletion of the SAM domain induces a complex hindlimb defect associated with down-regulation of Trp63, a known split-hand/split-foot malformation disease gene. Our results identify ZAK as a key player in mammalian limb patterning and demonstrate the rapid utility of CRISPR/Cas genome editing to assign causality to human mutations in the mouse in <10 wk.
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Deformidades Congénitas de las Extremidades/genética , Quinasas Quinasa Quinasa PAM/genética , Proteínas Quinasas/genética , Secuencia de Aminoácidos , Animales , Proteínas Bacterianas , Proteína 9 Asociada a CRISPR , Línea Celular , Repeticiones Palindrómicas Cortas Agrupadas y Regularmente Espaciadas , Técnicas de Cocultivo , Endonucleasas , Exoma , Femenino , Humanos , Escala de Lod , Quinasas Quinasa Quinasa PAM/química , Masculino , Ratones , Ratones de la Cepa 129 , Ratones Endogámicos C57BL , Ratones Noqueados , Mutagénesis Sitio-Dirigida , Mutación Missense , Linaje , Polimorfismo de Nucleótido Simple , Proteínas Quinasas/química , Análisis de Secuencia de ADNRESUMEN
Biallelic mutations of ALS2 cause a clinical spectrum of overlapping autosomal recessive neurodegenerative disorders: infantile-onset ascending hereditary spastic paralysis (IAHSP), juvenile primary lateral sclerosis (JPLS), and juvenile amyotrophic lateral sclerosis (ALS2). We report on eleven individuals affected with IAHSP from two consanguineous Pakistani families. A combination of linkage analysis with homozygosity mapping and targeted sequencing identified two novel ALS2 mutations, a c.194T > C (p.Phe65Ser) missense substitution located in the first RCC-like domain of ALS2/alsin and a c.2998delA (p.Ile1000*) nonsense mutation. This study of extended families including a total of eleven affected individuals suggests that a given ALS2 mutation may lead to a phenotype with remarkable intrafamilial clinical homogeneity.
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Predisposición Genética a la Enfermedad/genética , Factores de Intercambio de Guanina Nucleótido/genética , Mutación/genética , Paraplejía Espástica Hereditaria/genética , Adolescente , Adulto , Edad de Inicio , Niño , Análisis Mutacional de ADN , Salud de la Familia , Femenino , Humanos , Masculino , Pakistán , Adulto JovenRESUMEN
BACKGROUND: Grebe dysplasia, Hunter-Thompson dysplasia, and du Pan dysplasia constitute a spectrum of skeletal dysplasias inherited as an autosomal recessive trait characterized by short stature, severe acromesomelic shortening of the limbs, and normal axial skeleton. The majority of patients with these disorders have biallelic loss-of-function mutations of GDF5. In single instances, Grebe dysplasia and a Grebe dysplasia-like phenotype with genital anomalies have been shown to be caused by mutations in BMPR1B, encoding a GDF5 receptor. METHODS: We clinically and radiologically characterised an acromesomelic chondrodysplasia in an adult woman born to consanguineous parents. We sequenced GDF5 and BMPR1B on DNA of the proposita. We performed 3D structural analysis and luciferase reporter assays to functionally investigate the identified BMPR1B mutation. RESULTS: We extend the genotype-phenotype correlation in the acromesomelic chondrodysplasias by showing that the milder du Pan dysplasia can be caused by a hypomorphic BMPR1B mutation. We show that the homozygous c.91C>T, p.(Arg31Cys) mutation causing du Pan dysplasia leads to a significant loss of BMPR1B function, but to a lesser extent than the previously reported p.Cys53Arg mutation that results in the more severe Grebe dysplasia. CONCLUSIONS: The phenotypic severity gradient of the clinically and radiologically related acromesomelic chondrodysplasia spectrum of skeletal disorders may be due to the extent of functional impairment of the ligand-receptor pair GDF5-BMPR1B.
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Receptores de Proteínas Morfogenéticas Óseas de Tipo 1/genética , Enanismo/genética , Osteocondrodisplasias/genética , Adulto , Enanismo/etiología , Femenino , Factor 5 de Diferenciación de Crecimiento/genética , Humanos , Mutación , Osteocondrodisplasias/etiología , FenotipoRESUMEN
Holoprosencephaly is a clinically and genetically heterogeneous midline brain malformation associated with neurologic manifestations including developmental delay, intellectual disability and seizures. Although mutations in the sonic hedgehog gene SHH and more than 10 other genes are known to cause holoprosencephaly, many patients remain without a molecular diagnosis. Here we show that a homozygous truncating mutation of STIL not only causes severe autosomal recessive microcephaly, but also lobar holoprosencephaly in an extended consanguineous Pakistani family. STIL mutations have previously been linked to centrosomal defects in primary microcephaly at the MCPH7 locus. Our results thus expand the clinical phenotypes associated with biallellic STIL mutations to include holoprosencephaly.
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Holoprosencefalia/genética , Péptidos y Proteínas de Señalización Intracelular/genética , Microcefalia/genética , Mutación/genética , Adolescente , Adulto , Preescolar , Consanguinidad , Femenino , Humanos , Lactante , Masculino , Pakistán , Adulto JovenRESUMEN
Dopamine transporter deficiency syndrome due to SLC6A3 mutations is the first inherited dopamine 'transportopathy' to be described, with a classical presentation of early infantile-onset progressive parkinsonism dystonia. In this study we have identified a new cohort of patients with dopamine transporter deficiency syndrome, including, most significantly, atypical presentation later in childhood with a milder disease course. We report the detailed clinical features, molecular genetic findings and in vitro functional investigations undertaken for adult and paediatric cases. Patients presenting with parkinsonism dystonia or a neurotransmitter profile characteristic of dopamine transporter deficiency syndrome were recruited for study. SLC6A3 mutational analysis was undertaken in all patients. The functional consequences of missense variants on the dopamine transporter were evaluated by determining the effect of mutant dopamine transporter on dopamine uptake, protein expression and amphetamine-mediated dopamine efflux using an in vitro cellular heterologous expression system. We identified eight new patients from five unrelated families with dopamine transporter deficiency syndrome. The median age at diagnosis was 13 years (range 1.5-34 years). Most significantly, the case series included three adolescent males with atypical dopamine transporter deficiency syndrome of juvenile onset (outside infancy) and progressive parkinsonism dystonia. The other five patients in the cohort presented with classical infantile-onset parkinsonism dystonia, with one surviving into adulthood (currently aged 34 years) and labelled as having 'juvenile parkinsonism'. All eight patients harboured homozygous or compound heterozygous mutations in SLC6A3, of which the majority are previously unreported variants. In vitro studies of mutant dopamine transporter demonstrated multifaceted loss of dopamine transporter function. Impaired dopamine uptake was universally present, and more severely impacted in dopamine transporter mutants causing infantile-onset rather than juvenile-onset disease. Dopamine transporter mutants also showed diminished dopamine binding affinity, reduced cell surface transporter, loss of post-translational dopamine transporter glycosylation and failure of amphetamine-mediated dopamine efflux. Our data series expands the clinical phenotypic continuum of dopamine transporter deficiency syndrome and indicates that there is a phenotypic spectrum from infancy (early onset, rapidly progressive disease) to childhood/adolescence and adulthood (later onset, slower disease progression). Genotype-phenotype analysis in this cohort suggests that higher residual dopamine transporter activity is likely to contribute to postponing disease presentation in these later-onset adult cases. Dopamine transporter deficiency syndrome remains under-recognized and our data highlights that dopamine transporter deficiency syndrome should be considered as a differential diagnosis for both infantile- and juvenile-onset movement disorders, including cerebral palsy and juvenile parkinsonism.
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Proteínas de Transporte de Dopamina a través de la Membrana Plasmática/deficiencia , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática/genética , Estudios de Asociación Genética , Trastornos del Movimiento/genética , Adolescente , Adulto , Edad de Inicio , Niño , Preescolar , Análisis Mutacional de ADN , Femenino , Humanos , Immunoblotting , Lactante , Masculino , Trastornos del Movimiento/complicaciones , Linaje , Fenotipo , Reacción en Cadena de la Polimerasa , Adulto JovenRESUMEN
CHEK2 encodes a serine/threonine-protein kinase which plays a critical role in DNA damage signaling pathways. CHEK2 directly phosphorylates and regulates the functions of p53 and BRCA1. Most women with breast and/or ovarian cancer are not carriers of mutant BRCA1 or BRCA2. Multiple studies have shown that a CHEK2*1100delC confers about a two-fold increased risk of breast cancer in unselected females and a tenfold increase in males. Moreover, studies have shown that first-degree relatives of bilateral breast cancer cases who carried the CHEK2*1100delC allele had an eight-fold increased risk of breast cancer. It has been suggested that CHEK2 functions as a low-penetrance susceptibility gene for cancers and multiplies the risks associated with other gene(s) to increase cancer risk. The main goal of this study was to evaluate and to compare the role of truncating mutations, splice junction mutations and rare missense substitutions in breast cancer susceptibility gene CHEK2. Present study was performed on 140 individuals including 70 breast cancer patients both with and without family history and 70 normal individuals. Written consent was obtained and 3 ml intravenous blood was drawn from all the subjects. DNA was extracted from all the samples through inorganic method published already. Primers were synthesized for all the 14 exons of CHEK2 gene. Coding and adjacent intronic sequences of CHEK2 gene were amplified and sequenced. Two genetic variants (p.H371Y, p.D438Y) were found in exon 10 and exon 11 of gene CHEK2 which were not found in any of the 70 control individuals from same geographical area and ethnic group. The genetic variant c.1312G>T (p.D438Y) identified in a patient with a family history of breast cancer. To our knowledge, this is first mutation scanning study of gene CHEK2 from Balochistan population.
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Neoplasias de la Mama/genética , Quinasa de Punto de Control 2/genética , Estudios de Asociación Genética , Predisposición Genética a la Enfermedad , Neoplasias de la Mama/patología , Femenino , Heterocigoto , Humanos , Persona de Mediana Edad , Mutación Missense , Linaje , Factores de RiesgoRESUMEN
Acromesomelic chondrodysplasias (ACDs) are characterized by disproportionate shortening of the appendicular skeleton, predominantly affecting the middle (forearms and forelegs) and distal segments (hands and feet). Here, we present two consanguineous families with missense (c.157T>C, p.(C53R)) or nonsense (c.657G>A, p.(W219*)) mutations in BMPR1B. Homozygous affected individuals show clinical and radiographic findings consistent with ACD-type Grebe. Functional analysis of the missense mutation C53R revealed that the mutated receptor was partially located at the cell membrane. In contrast to the wild-type receptor, C53R mutation hindered the activation of the receptor by its ligand GDF5, as shown by reporter gene assay. Further, overexpression of the C53R mutation in an in vitro chondrogenesis assay showed no effect on cell differentiation, indicating a loss of function. The nonsense mutation (c.657G>A, p.(W219*)) introduces a premature stop codon, which is predicted to be subject to nonsense-mediated mRNA decay, causing reduced protein translation of the mutant allele. A loss-of-function effect of both mutations causing recessive ACD-type Grebe is further supported by the mild brachydactyly or even non-penetrance of these mutations observed in the heterozygous parents. In contrast, dominant-negative BMPR1B mutations described previously are associated with autosomal-dominant brachydactyly-type A2.
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Receptores de Proteínas Morfogenéticas Óseas de Tipo 1/genética , Codón sin Sentido , Anomalías Musculoesqueléticas/genética , Mutación Missense , Osteocondrodisplasias/genética , Adolescente , Secuencia de Aminoácidos , Animales , Preescolar , Consanguinidad , Análisis Mutacional de ADN , Salud de la Familia , Femenino , Homocigoto , Humanos , Masculino , Ratones , Datos de Secuencia Molecular , Anomalías Musculoesqueléticas/patología , Células 3T3 NIH , Osteocondrodisplasias/patología , Linaje , Fenotipo , Homología de Secuencia de Aminoácido , Adulto JovenAsunto(s)
Empalme Alternativo , Exones , Mutación , Obesidad/genética , Receptores de Leptina/genética , Edad de Inicio , Niño , Preescolar , Consanguinidad , Análisis Mutacional de ADN , Femenino , Humanos , Masculino , Sitios de Empalme de ARNRESUMEN
Epileptic encephalopathies are genetically heterogeneous severe disorders in which epileptic activity contributes to neurological deterioration. We studied two unrelated children presenting with a distinctive early-onset epileptic encephalopathy characterized by refractory epilepsy and absent developmental milestones, as well as thick and short corpus callosum and persistent cavum septum pellucidum on brain MRI. Using whole-exome sequencing, we identified biallelic mutations in seizure threshold 2 (SZT2) in both affected children. The causative mutations include a homozygous nonsense mutation and a nonsense mutation together with an exonic splice-site mutation in a compound-heterozygous state. The latter mutation leads to exon skipping and premature termination of translation, as shown by RT-PCR in blood RNA of the affected boy. Thus, all three mutations are predicted to result in nonsense-mediated mRNA decay and/or premature protein truncation and thereby loss of SZT2 function. Although the molecular role of the peroxisomal protein SZT2 in neuronal excitability and brain development remains to be defined, Szt2 has been shown to influence seizure threshold and epileptogenesis in mice, consistent with our findings in humans. We conclude that mutations in SZT2 cause a severe type of autosomal-recessive infantile encephalopathy with intractable seizures and distinct neuroradiological anomalies.