Biallelic loss of function variants in FUZ result in an orofaciodigital syndrome.

Orofaciodigital syndrome is a distinctive subtype of skeletal ciliopathies. Disease-causing variants in the genes encoding the CPLANE complex result in a wide variety of skeletal dysplasia with disturbed ciliary functions. The phenotypic spectrum includes orofaciodigital syndrome and short rib polydactyly syndrome. FUZ, as a part of the CPLANE complex, is involved in intraflagellar vesicular trafficking within primary cilia. Previously, the variants, c.98_111+9del and c.851G>T in FUZ were identified in two individuals with a skeletal ciliopathy, manifesting digital anomalies (polydactyly, syndactyly), orofacial cleft, short ribs and cardiac defects. Here, we present two novel variants, c.601G>A and c.625_636del in biallelic state, in two additional subjects exhibiting phenotypic overlap with the previously reported cases. Our findings underscore the association between biallelic loss of function variants in FUZ and skeletal ciliopathy akin to orofaciodigital syndrome.

Intragenic homozygous duplication in HEPACAM is associated with megalencephalic leukoencephalopathy with subcortical cysts type 2A.

Disease-causing variants in HEPACAM are associated with megalencephalic leukoencephalopathy with subcortical cysts 2A (MLC2A, MIM# 613,925, autosomal recessive), and megalencephalic leukoencephalopathy with subcortical cysts 2B, remitting, with or without impaired intellectual development (MLC2B, MIM# 613,926, autosomal dominant). These disorders are characterised by macrocephaly, seizures, motor delay, cognitive impairment, ataxia, and spasticity. Brain magnetic resonance imaging (MRI) in these individuals shows swollen cerebral hemispheric white matter and subcortical cysts, mainly in the frontal and temporal regions. To date, 45 individuals from 39 families are reported with biallelic and heterozygous variants in HEPACAM, causing MLC2A and MLC2B, respectively. A 9-year-old male presented with developmental delay, gait abnormalities, seizures, macrocephaly, dysarthria, spasticity, and hyperreflexia. MRI revealed subcortical cysts with diffuse cerebral white matter involvement. Whole-exome sequencing (WES) in the proband did not reveal any clinically relevant single nucleotide variants. However, copy number variation analysis from the WES data of the proband revealed a copy number of 4 for exons 3 and 4 of HEPACAM. Validation and segregation were done by quantitative PCR which confirmed the homozygous duplication of these exons in the proband and carrier status in both parents. To the best of our knowledge, this is the first report of an intragenic duplication in HEPACAM causing MLC2A.

Further validation of craniosynostosis as a part of phenotypic spectrum of BCL11B-related BAFopathy.

Heterozygous disease-causing variants in BCL11B are the basis of a rare neurodevelopmental syndrome with craniofacial and immunological involvement. Isolated craniosynostosis, without systemic or immunological findings, has been reported in one of the 17 individuals reported with this disorder till date. We report three additional individuals harboring de novo heterozygous frameshift variants, all lying in the exon 4 of BCL11B. All three individuals presented with the common findings of this disorder i.e. developmental delay, recurrent infections with immunologic abnormalities and facial dysmorphism. Notably, craniosynostosis of variable degree was seen in all three individuals. We, thus add to the evolving genotypes and phenotypes of BCL11B-related BAFopathy and also review the clinical, genomic spectrum along with the underlying disease mechanisms of this disorder.

Report of rapid diagnosis and precise management of MMADHC-related intracellular cobalamin defect.

Disorders of intracellular cobalamin metabolism are a group of metabolic disorders that lead to varied clinical presentation from intrauterine life to adulthood. We report a male infant with developmental regression, macrocytic anaemia and hyperpigmentation. Exome sequencing identified a homozygous pathogenic variant in the MMADHC gene, known to cause homocystinuria, cblD type (MIM #277410). We describe significant clinical improvement with targeted therapy and emphasise the relevance of genomic testing in accurate management of inherited metabolic disorders.

Genetic disorders with central nervous system white matter abnormalities: An update.

Several genetic disorders have variable degree of central nervous system white matter abnormalities. We retrieved and reviewed 422 genetic conditions with prominent and consistent involvement of white matter from the literature. We herein describe the current definitions, classification systems, clinical spectrum, neuroimaging findings, genomics, and molecular mechanisms of these conditions. Though diagnosis for most of these disorders relies mainly on genomic tests, specifically exome sequencing, we collate several clinical and neuroimaging findings still relevant in diagnosis of clinically recognizable disorders. We also review the current understanding of pathophysiology and therapeutics of these disorders.

Spectrum of ARSA variations in Asian Indian patients with Arylsulfatase A deficient metachromatic leukodystrophy.

Metachromatic leukodystrophy due to Arylsulfatase A enzyme deficiency is an autosomal recessive disorder caused by biallelic variations in ARSA gene. Till date 186 variations have been reported in ARSA gene worldwide, but the variation spectrum in India is not known. The aim of this study was to identify the variation profile in Indian patients presenting with features of Arylsulfatase A deficient metachromatic leukodystrophy. We sequenced the ARSA gene in 51 unrelated families and identified 36 variants out of which 16 were novel. The variations included 23 missense, 3 nonsense, and 6 frameshift variants (3 single-base deletions and 3 single-base duplications), 1 indel, one 3 bp deletion, and 2 splice site variations. The pathogenicity of the novel variations was inferred with the help of mutation prediction softwares like MutationTaster, SIFT, Polyphen-2, PROVEAN, and HANSA. The effects of the identified sequence variants on the protein structure were studied using in silico methods. The most common variation was c.931 C > T(p.Arg311*), found in 11.4% (14 out of 122 alleles) of the tested individuals. To the best of our knowledge, this study is the first of its kind in India with respect to the size of the cohort and the molecular diagnostic method used and one of the largest cohorts of metachromatic leukodystrophy studied till date.

Concepts, Utility and Limitations of Cord Blood Banking: What Clinicians Need to Know.

Stem cell transplantation and cord blood banking have received much popularity among general public and medical professionals in the recent past. But information about the scientific aspects, its utility and limitations is incomplete amongst laypersons as well as many medical practitioners. Stem cells differ from all other types of cells in the human body because of their ability to multiply in order to self perpetuate and differentiate into specialized cells. Stems cells could be totipotent, multipotent, pluripotent, oligopotent or unipotent depending on the type of cells that can arise or differentiate from them. Umbilical cord blood serves as a potent source of hematopoeitic stem cells and is being used to treat various disorders like blood cancers, hemoglobinopathies and immunodeficiency disorders for which hematological stem cell transplantation is the standard of care. Cord blood can be collected at ease, without any major complications and has a lower incidence of graft vs. host reaction compared to bone marrow cells or peripheral blood cells. Both public and private banks have been established for collection and storage of umbilical cord blood. However, false claims and misleading commercial advertisements about the use of umbilical cord blood stem cells for the treatment of a variety of conditions ranging from neuromuscular disorders to cosmetic benefits are widespread and create unrealistic expectations in laypersons and clinicians. Many clinicians and laypersons are unaware of the limitations of cord blood banking, as in treating a genetic disorder by autologous cord blood transplant. Knowledge and awareness about the scientific indications of cord blood stem cell transplantation and realistic expectations about the utility of cord blood among medical practitioners are essential for providing accurate information to laypersons before they decide to preserve umbilical cord blood in private banks and thus prevent malpractice.

Malan syndrome: Extension of genotype and phenotype spectrum.

Malan syndrome and Marshall-Smith syndrome (MSS) are allelic disorders caused by mutation in NFIX gene. We report a 3-year- 6 months- old female with clinical features suggestive of Malan syndrome with mutation in exon 2 of NFIX gene. NFIX gene, where most of the mutations in Malan syndrome are located. She did not have advanced bone age. The radiographs of long bones showed metaphyseal changes which were not reported previously. This study reports the first mutation proven case from India and highlights the overlap between MSS and Malan syndrome.

Metatropic Dysplasia with a Novel Mutation in TRPV4.

BACKGROUND: Metatropic dysplasia is a skeletal dysplasia characterized by rhizomelia, severe kyphoscoliosis and a coccygeal tail. CASE CHARACTERISTICS: A 12 day-old male neonate had facial dysmorphism, short limbs and coccygeal tail and showed radiological features of metatropic dysplasia. OBSERVATION: A novel heterozygous variant was observed in TRPV4 gene. MESSAGE: We report a novel mutation in an Indian neonate with metatropic dysplasia.

Cartilage Hair Hypoplasia: Two Unrelated Cases with g.70 A > G Mutation in RMRP Gene.

Cartilage-hair hypoplasia is an autosomal recessive disorder, characterized by short stature, metaphyseal dysplasia, hypotrichosis and immunodeficiency. More than 90 different biallelic mutations in RMRP gene have been identified to cause this condition. Three cases previously reported from India showed novel mutations in RMRP gene. The authors report two unrelated cases with the more common g.70A > G mutation, stressing the need to screen for this mutation in Indian population having features of cartilage-hair hypoplasia.