The spectrum of neurological manifestations and genotype-phenotype correlation in Indian children with Gaucher disease.

Gaucher disease (GD), one of the most frequent autosomal recessive lysosomal storage disorders, occurs due to bi-allelic pathogenic variants in the GBA1. Worldwide, the c.1448T>C (L483P) homozygous pathogenic variant is reported to be associated with neurological GD phenotype. Clinical distinction between GD1 and GD3 may be challenging due to subtle neurological features. Objective methods to evaluate neurological signs and saccades may help in early diagnosis. This study was conducted to assess the neurological phenotype, and its severity using a modified severity scoring tool (mSST), and the genotype-phenotype correlation. A total of 45 children aged 2 years 6 months to 15 years with a confirmed enzymatic and molecular diagnosis of GD with or without therapy were recruited. mSST tool was used to assess the severity of the neurological phenotype. A digital eye movement tracker (View Point Tracker) was used to assess eye movements. Clinical and genetic findings were analyzed. Out of 45 patients, 39 (86.7%) had at least one neurological phenotype detected using the mSST tool, with impairment of cognitive function (68.8%, 31/45) being the commonest feature. Thirty-two of 45 (71%) were assessed for saccadic eye movements using the eye tracker. Of these, 62.5% (20/32) had absent saccades. Four children (8.9%, 4/32) without clinical oculomotor apraxia had absent saccades on the viewpoint eye tracker. Overall, 77.7% (35/45), had homozygosity for c.1448T>C in GBA1 of which 91.4% (32/35) had neurological manifestations. Other alleles associated with neurological phenotype included c.1603C>T(p.R535C), c.1184C>T (p.S395F), c.115+1G>A (g.4234G>A), c.260G>A (p.R87Q) and c.1352A>G (p.Y451C). To conclude, in India, the c.1448T>C pathogenic variant in GBA1 is the commonest  and is associated with neurological phenotype of GD. Therefore, every patient of GD should be assessed using the mSST scoring tool for an early pick up of neurological features. The routine use of a viewpoint eye tracker in children with GD would be useful for early recognition of saccadic abnormalities.

Hydrops fetalis in PKD1L1-related heterotaxy: Report of two foetuses and expanding the phenotypic and molecular spectrum.

Abnormalities in the normal left-right axis asymmetry range from situs inversus totalis to situs ambiguous or heterotaxy. More than 80 genes have been described to have a role in the establishment of the normal situs of the internal organs. Pathogenic variants in the PKD1L1 gene have recently been described in heterotaxy and congenital heart disease. Till date, 11 families have been described with PKD1L1-related heterotaxy. We describe the first Indian family with two affected foetuses with PKD1L1-related nonimmune hydrops, congenital heart disease, situs inversus, and heterotaxy, with biallelic variants in the compound heterozygous state.

Utility of fetal whole exome sequencing in the etiological evaluation and outcome of nonimmune hydrops fetalis.

INTRODUCTION: Nonimmune hydrops fetalis (NIHF) has varied etiology. We assessed the etiological spectrum and evaluated the utility of fetal whole exome sequencing (fWES) for the diagnosis of NIHF. METHODS: In this prospective cohort study, we evaluated antenatally diagnosed fetuses with NIHF between July 2018 and December 2019 according to the routine diagnostic algorithm. Fetuses that remained undiagnosed after routine NIHF workup were subjected to fetal chromosomal microarray and/or WES. Pregnancies were followed up for clinical outcomes. RESULTS: Of the 45 fetuses, consanguinity and recurrent hydrops fetalis were observed in 13.3% (6/45) and 28.8% (13/45), respectively. Overall, an etiological diagnosis was possible in 75.5% (34/45) of fetuses, while the cause remained unknown in 24.4% (11/45). A genetic etiology was identified in 46.6% (21/45): aneuploidy and monogenic disorders in 28.8% (13/45) and 17.8% (8/45), respectively. fWES on 19 fetuses detected disease-causing variants in 42.1% (8/19). Nine novel variants were detected in RAPSN, ASCC1, NEB, PKD1L1, GUSB, and PIEZO1. Only 8.8% (4/45) of the cohort survived without morbidity. CONCLUSIONS: This study describes the etiological spectrum and the disease-causing variants in an Indian cohort of hydropic fetuses.

Epigenetic Abnormalities of 11p15.5 Region in Beckwith-Wiedemann Syndrome - A Report of Eight Indian Cases.

OBJECTIVES: To report a phenotypic series of eight patients of Beckwith-Wiedemann Syndrome (BWS) with abnormalities of 11p15.5 region to highlight the spectrum of phenotypic manifestations. METHODS: All the cases were evaluated using Methylation Specific Multiplex Ligation Dependent Probe Amplification (MS-MLPA) of 11p15.5 region to detect the abnormal methylation status of ICR1 (H19DR) and ICR2 (KvDMR) regions. RESULTS: The median age at diagnosis was 5.7 mo (range 1.5-13 mo) with female preponderance. Macroglossia, ear creases and abdominal wall defects were the major features. Hypomethylation at ICR2 and hypermethylation at ICR1 was observed in 6/8 and 2/8 patients respectively. No specific genotype and phenotype correlation was observed. CONCLUSIONS: This report highlights the major clinical features of BWS that should prompt pediatricians to offer genetic testing to evaluate the epigenetic abnormalities using MS-MLPA, as it not only helps in appropriate counseling but also provides further guidance about the tumor risk surveillance.

Mevalonate Kinase Deficiency as Cause of Periodic Fever in Two Siblings.

Mevalonate kinase deficiency (MKD) is a rare autosomal recessive autoinflammatory disease caused by mutations in MVK. We report two siblings with MKD, presenting with recurrent febrile illnesses, detected to have compound heterozygous variants in MVK. MKD mimics common pediatric conditions and should be considered as a differential diagnosis.

Methylene Tetrahydrofolate Reductase Deficiency.

5,10-Methylene-tetrahydrofolate reductase (MTHFR) deficiency is a rare, autosomal recessive, metabolic disorder of folate metabolism, which affects homocysteine remethylation. Elevated homocysteine with normal or low methionine level is the key to diagnosis. Early recognition and treatment with betaine, has been shown to improve the survival and neurological outcomes. The authors report five Indian patients from three unrelated families, with MTHFR deficiency to emphasize the importance of early recognition and initiation of specific treatment.

Report of a Novel Homozygous Nonsense DDR2 Mutation in an Indian Adult Male with Spondylo-meta-epiphyseal Dysplasia, Short Limb-Abnormal Calcification Type.

Spondylo-meta-epiphyseal dysplasia, short limb-abnormal calcification type is a rare autosomal recessive disorder causing severe disproportionate short stature along with typical radiological features. We report an adult male patient with typical features and a novel homozygous nonsense mutation c.2422C > T (p.Gln808Ter) in DDR2 . This is the first report of the disease from India.