Complex chromosomal rearrangements in female carriers experiencing recurrent pregnancy loss or poor obstetric history and literature review.

Purpose: Complex chromosomal rearrangements (CCRs) often remain unidentified as they are rarely observed in the general population. Females with CCRs are generally recognized on the identification of an affected child with multiple congenital anomalies (MCA) or having a history of repeated pregnancy loss/bad obstetric history (RPL/BOH). In contrast, males with CCRs are diagnosed primarily due to infertility.

Late infantile and adult-onset metachromatic leukodystrophy due to novel missense variants in the gene: Case report from India.

Metachromatic leukodystrophy (MLD) due to Sap-B deficiency is a rare autosomal recessive disorder caused due to biallelic variants in the gene. The gene encodes a precursor protein prosaposin, which is subsequently cleaved to form four active glycoproteins: Sap-A, Sap-B, Sap-C, and Sap-D. In case of deficiency of the sphingolipid activator protein Sap-B, there is a gradual accumulation of cerebroside-3-sulfate in the myelin of the nervous system resulting in progressive demyelination.

A novel case of two siblings harbouring homozygous variant in the NEUROG1 gene with autism as an additional phenotype: a case report.

Introduction: NEUROG1 gene is yet to be associated with a set of human phenotypes in the OMIM database. Three cases have previously been diagnosed with cranial dysinnervation due to biallelic variants in the NEUROG1 gene. This is the fourth and a novel report of a sibling pair harboring a homozygous variant in the NEUROG1 gene with autism as an additional phenotype.

The GALNS p.P77R variant is a probable Gujarati-Indian founder mutation causing Mucopolysaccharidosis IVA syndrome.

Background: Mucopolysaccharidosis IVA (Morquio syndrome A, MPS IVA) is an autosomal recessive lysosomal storage disorder caused due to biallelic variants in the N-acetylgalactoseamine-6-sulfate sulfatase (GALNS) gene. The mutation spectrum in this condition is determined amongst sub-populations belonging to the north, south and east India geography, however, sub-populations of west Indian origin, especially Gujarati-Indians, are yet to be studied. We aimed to analyse the variants present in the GLANS gene amongst the population of Gujarat by sequencing all exons and exon-intron boundaries of the GALNS gene in patients from 23 unrelated families.

An ultra-rare case of immunoskeletal dysplasia with neurodevelopmental abnormalities in an Indian patient with homozygous c.953C > T variant in EXTL3 gene: a case report.

Background: Immunoskeletal dysplasia with neurodevelopmental abnormalities (ISDNA) is an ultra-rare genetic condition that belongs to the group of spondyloepimetaphyseal dysplasias. It is caused due to presence of biallelic variants in the EXTL3 gene. The encoded exostosin like glycosyltransferase 3 (EXTL3) protein plays a key role in heparan sulfate synthesis.

Assessing Utility of Clinical Exome Sequencing in Diagnosis of Rare Idiopathic Neurodevelopmental Disorders in Indian Population.

Background: Neurological diseases are phenotypically and genotypically heterogeneous. Clinical exome sequencing (CES) has been shown to provide a high diagnostic yield for these disorders in the European population but remains to be demonstrated for the Indian population.

Objective: The study aimed to understand the utility of clinical exome sequencing for the diagnosis of neurodevelopmental disorders.

Mosaic chromosome 18 anomaly delineated in a child with dysmorphism using a three-pronged cytogenetic techniques approach: a case report.

Background: A plethora of cases are reported in the literature with iso- and ring-chromosome 18. However, co-occurrence of these two abnormalities in an individual along with a third cell line and absence of numerical anomaly is extremely rare.

Case Presentation: A 7-year-old female was referred for diagnosis due to gross facial dysmorphism and severe developmental delay.

Identification of novel variants in a large cohort of children with Tay-Sachs disease: An initiative of a multicentric task force on lysosomal storage disorders by Government of India.

Tay-Sachs disease (TSD) (OMIM) is a neurodegenerative lysosomal storage disorder caused due to mutations in the HEXA gene. To date, nearly 190 mutations have been reported in HEXA gene. Here, we have characterized 34 enzymatically confirmed TSD families to investigate the presence of novel as well as known variants in HEXA gene.

Multi-gene testing in neurological disorders showed an improved diagnostic yield: data from over 1000 Indian patients.

Background: Neurological disorders are clinically heterogeneous group of disorders and are major causes of disability and death. Several of these disorders are caused due to genetic aberration. A precise and confirmatory diagnosis in the patients in a timely manner is essential for appropriate therapeutic and management strategies.

Rare cause of Hemophagocytic Lymphohistiocytosis due to mutation in PRF1 and SH2D1A genes in two children - a case report with a review.

Background: Hemophagocytic Lymphohistiocytosis (HLH) is a rare, complex, life-threatening hyper-inflammatory condition due to over activation of lymphocytes mediated secretory cytokines in the body. It occurs as a primary HLH due to genetic defect that mostly occurs in the childhood and associated with early neonatal death. Secondary HLH is triggered by secondary to infection and can occur at any age.

Elucidation of the phenotypic spectrum and genetic landscape in primary and secondary microcephaly.

Purpose: Microcephaly is a sign of many genetic conditions but has been rarely systematically evaluated. We therefore comprehensively studied the clinical and genetic landscape of an unselected cohort of patients with microcephaly.

Methods: We performed clinical assessment, high-resolution chromosomal microarray analysis, exome sequencing, and functional studies in 62 patients (58% with primary microcephaly [PM], 27% with secondary microcephaly [SM], and 15% of unknown onset).

Gaucher disease: single gene molecular characterization of one-hundred Indian patients reveals novel variants and the most prevalent mutation.

Background: Gaucher disease is a rare pan-ethnic, lysosomal storage disorder resulting due to beta-Glucosidase (GBA1) gene defect. This leads to the glucocerebrosidase enzyme deficiency and an increased accumulation of undegraded glycolipid glucocerebroside inside the cells' lysosomes. To date, nearly 460 mutations have been described in the GBA1 gene.

Batten disease: biochemical and molecular characterization revealing novel PPT1 and TPP1 gene mutations in Indian patients.

Background: Neuronal ceroid lipofuscinoses type I and type II (NCL1 and NCL2) also known as Batten disease are the commonly observed neurodegenerative lysosomal storage disorder caused by mutations in the PPT1 and TPP1 genes respectively. Till date, nearly 76 mutations in PPT1 and approximately 140 mutations, including large deletion/duplications, in TPP1 genes have been reported in the literature. The present study includes 34 unrelated Indian patients (12 females and 22 males) having epilepsy, visual impairment, cerebral atrophy, and cerebellar atrophy.

A child with intellectual disability and dysmorphism due to complex ring chromosome 6: identification of molecular mechanism with review of literature.

Background: Ring chromosome 6 (r(6)) is a rare disorder that mainly occurs as a 'de novo' event. Nonetheless, a wide phenotypic spectrum has been reported in r(6) cases, depending on breakpoints, size of involved region, copy number alterations and mosaicism of cells with r(6) and/or monosomy 6 due to loss of r(6).

Case Presentation: An 11-year-old male was referred with developmental delay, intellectual disability and microcephaly.

Biochemical and molecular characterization of adult patients with type I Gaucher disease and carrier frequency analysis of Leu444Pro - a common Gaucher disease mutation in India.

Background: Gaucher disease is a rare pan-ethnic disorder which occurs due to an increased accumulation of undegraded glycolipid glucocerebroside inside the cells' lysosomes. A beta-Glucosidase (GBA) gene defect results in glucocerebrosidase enzyme deficiency. Though the disease is mainly diagnosed in childhood, the adult manifestation is often missed or identified late due to the failure to recognize the heterogeneous clinical presentation.

Identification of deletion-duplication in HEXA gene in five children with Tay-Sachs disease from India.

Background: Tay-Sachs disease (TSD) is a sphingolipid storage disorder caused by mutations in the HEXA gene. To date, nearly 170 mutations of HEXA have been described, including only one 7.6 kb large deletion.

A case of Raine syndrome presenting with facial dysmorphy and review of literature.

Background: Raine syndrome (RS) - an extremely rare autosomal recessive genetic disorder, is caused by a biallelic mutation in the FAM20C gene. Some of the most common clinical features include generalized osteosclerosis with a periosteal bone formation, dysmorphic face, and thoracic hypoplasia. Many cases have also been reported with oro-dental abnormalities, and developmental delay.

Harlequin ichthyosis due to novel splice site mutation in the ABCA12 gene: postnatal to prenatal diagnosis.

Background: Harlequin ichthyosis (HI) is a severe genetic disorder caused by the mutation in the ABCA12 gene. Infants born with this condition have markedly thickened, hard stratum corneum skin all over the body.

Methods: A female child born with a thick white plate of skin with deep cracks all over the body was investigated for genes associated with congenital Ichthyosis by Next Generation sequencing.