Clinical exome sequencing facilitates the understanding of genetic heterogeneity in Leber congenital amaurosis patients with variable phenotype in southern India

Background:Leber congenital amaurosis(LCA),primarily characterized by retinal degeneration is the most severe form of inherited retinal dystrophy(IRD)responsible for congenital blindness.The presence of phenotypic heterogeneity makes the diagnosis of LCA challenging,especially in the absence of pronounced disease pathognomonic,yet it can be well comprehended by employing molecular diagnosis.Therefore,the present study aimed to reveal the causative mutations in ten LCA patients with variable phenotypes using clinical exome sequencing(CES).Methods:CES was performed in ten unrelated LCA patients.Ophthalmic information and family history of all patients were obtained to make a meaningful interpretation.The clinical exome data was analyzed and prioritized using a bioinformatics pipeline to identify mutations,which was further validated by Sanger sequencing.Segregation analysis was also performed on available family members.Results:CES led to the identification of causative mutations in nine LCA patients.Seven patients harbored a mutation in six LCA candidate genes,including RPE65,LCA5(n=2),CRX,PRPH2,CEP290,and ALMS1,while two patients possess a mutation in IFT80 and RP1,known to cause other diseases.Three novel mutations in LCA5(c.1823del),CRX(c.848del)and CEP290(c.2483G>T)were identified.The current study reports for the first time,a mutation in PRPH2,CEP290,and ALMS1 from the Indian population.Additionally,we observed a novel association of LCA phenotype with IFT80 known to cause Jeune syndrome.Based on the genetic finding,the patient AS09,who harbored a mutation in the RP1 gene,was re-diagnosed with early-onset retinitis pigmentosa.Conclusion:In conclusion,the results underline the importance of CES in clinically diagnosed LCA patients with variable phenotypes.The correlation between mutations in candidate genes and clinical phenotypes,helps to refine the clinical diagnosis.However,molecular evaluation with a larger cohort of LCA patients is needed for better understanding of the mutational spectrum in southern India.

The clinical and genetic characteristics in children with mitochondrial disease in China

Mitochondrial disease was a clinically and genetically heterogeneous group of diseases, thus the diagnosis was very difficult to clinicians. Our objective was to analyze clinical and genetic characteristics of children with mitochondrial disease in China. We tested 141 candidate patients who have been suspected of mitochondrial disorders by using targeted next-generation sequencing(NGS), and summarized the clinical and genetic data of gene confirmed cases from Neurology Department, Beijing Children's Hospital, Capital Medical University from October 2012 to January 2015. In our study, 40 cases of gene confirmed mitochondrial disease including eight kinds of mitochondrial disease, among which Leigh syndrome was identified to be the most common type, followed by mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes(MELAS). The age-of-onset varies among mitochondrial disease, but early onset was common. All of 40 cases were gene confirmed, among which 25 cases(62.5%)with mitochondrial DNA(mtDNA) mutation, and 15 cases(37.5%) with nuclear DNA(nDNA) mutation. M.3243A>G(n=7)accounts for a large proportion of mtDNA mutation. The nDNA mutations include SURF1(n=7),PDHA1(n=2),and NDUFV1,NDUFAF6, SUCLA2, SUCLG1, RRM2 B, and C12orf65, respectively.

An Unusual Case of BSND Gene–Related (Type IV) Bartter Syndrome Presenting as Antenatal Bartter Syndrome:A Case Report and Review of Literature

Bartter syndrome is a group of autosomal recessive renal tubular disorders;it has two types of presentation:antenatal and classic.The antenatal type presents as severe unexplained polyhydramnios in the second trimester.This is due to fetal urinary losses of sodium,chloride,and potassium,leading to fetal polyuria.The classic type presents in the late neonatal or infancy stage,with dehydration,dyselectrolytemia,failure to thrive,and nephrocalcinosis.Antenatal scans are normal in such cases.Type I and II Bartter syndrome presents in the antenatal period,whereas type IV has a classic presentation.We describe an unusual case of type IVa Bartter syndrome presenting in the antenatal period,with severe polyhydramnios.The initial diagnosis was made based on amniotic fluid chloride levels and later confirmed by performing a genetic test.Genetic testing is important for confirming diagnosis and prognostication regarding the condition.

A mysterious cause of recurrent acute liver dysfunction for over a decade

Introduction Acute liver failure(ALF)is an uncommon disease in pediatric cases.Etiology includes infections,autoimmune diseases,inborn errors of metabolism,and intoxications.Metabolic disorders account for 25%of resolved cases.However,the etiology remains unknown in half of pediatric ALF[1].The recognition of molecular etiopathogenesis has been facilitated after the common use of next-generation sequencing techniques.Recently,biallelic variants in neuroblastoma-amplified sequence(NBAS),Leucyl-tRNA synthetase 1(LARS1),and RAD50-interacting protein(RINT1)were identified in recurrent ALF(RALF)[2–4].