Genomic analyses in Cornelia de Lange Syndrome and related diagnoses: Novel candidate genes, genotype-phenotype correlations and common mechanisms.

Cornelia de Lange Syndrome (CdLS) is a rare, dominantly inherited multisystem developmental disorder characterized by highly variable manifestations of growth and developmental delays, upper limb involvement, hypertrichosis, cardiac, gastrointestinal, craniofacial, and other systemic features. Pathogenic variants in genes encoding cohesin complex structural subunits and regulatory proteins (NIPBL, SMC1A, SMC3, HDAC8, and RAD21) are the major pathogenic contributors to CdLS. Heterozygous or hemizygous variants in the genes encoding these five proteins have been found to be contributory to CdLS, with variants in NIPBL accounting for the majority (>60%) of cases, and the only gene identified to date that results in the severe or classic form of CdLS when mutated. Pathogenic variants in cohesin genes other than NIPBL tend to result in a less severe phenotype. Causative variants in additional genes, such as ANKRD11, EP300, AFF4, TAF1, and BRD4, can cause a CdLS-like phenotype. The common role that these genes, and others, play as critical regulators of developmental transcriptional control has led to the conditions they cause being referred to as disorders of transcriptional regulation (or "DTRs"). Here, we report the results of a comprehensive molecular analysis in a cohort of 716 probands with typical and atypical CdLS in order to delineate the genetic contribution of causative variants in cohesin complex genes as well as novel candidate genes, genotype-phenotype correlations, and the utility of genome sequencing in understanding the mutational landscape in this population.

Novel mutations in the glucocerebrosidase gene of Indian patients with Gaucher disease.

Gaucher disease (GD) is the most common glycolipid storage disorder resulting from glucocerebrosidase deficiency due to mutations in the GBA gene. Study was performed in 33 unrelated patients with low ß-glucosidase activity in leukocytes and/or fibroblasts. The exons and exon-intron boundaries of the GBA gene were bidirectionally sequenced using an automated sequencer. Mutations were confirmed in parents and were looked up in public databases, and in silico analysis was carried for novel mutations. We identified two novel missense mutations G289A (c.866G>C) and I466S (c.1397T>G) in exons 7 and 10, respectively, in two (6.06%) patients that destabilize the protein structure. L444P (c.1448T>C) was the most common mutation identified in 20/33 (60.60%) non-neuronopathic and 1/33 (3.03%) sub-acute neuronopathic form based on clinical presentation at the time of investigation. Other nine rare mutations were: R463C (c.1504C>T), R395C (c.1300C>T), R359Q (c.1193G>A), G355D (c.1181G>A), V352M (c.1171G>A) and S356F (c.1184C>T) found in each patient (18.18%). Compound heterozygous mutation L444P (c.1448T>C)/R496C (c.1603C>T) in exon 10/11 and L444P (c.1448T>C)/R329C (c.1102C>T) were observed in exon 10/8 in one each patient (6.06%). Two patients (6.06%) from Sri Lanka showed E326K (c.1093G>A) mutation in exon 8. We conclude that L444P is the most common mutant allele with exons 8 and 10 as the hot spot region of GBA gene observed in Indian GD patients.

Clinical and Mutational Characterizations of Ten Indian Patients with Beta-Ketothiolase Deficiency.

Beta-ketothiolase deficiency (mitochondrial acetoacetyl-CoA thiolase (T2) deficiency) is an inherited disease of isoleucine catabolism and ketone body utilization caused by ACAT1 mutations. We identified ten Indian patients who manifested with ketoacidotic episodes of variable severity. The patients showed increased urinary excretion of isoleucine-catabolic intermediates: 2-methyl-3-hydroxybutyrate, 2-methylacetoacetate, and tiglylglycine. Six patients had a favorable outcome, one died, and three developed neurodevelopmental sequela. Mutational analysis revealed a common (p.Met193Arg) and four novel (p.Ile323Thr, p.Ala215Asn, c.1012_1015dup, and c.730+1G>A) ACAT1 mutations. Transient expression analyses of wild-type and mutant cDNA were performed at 30, 37, and 40°C. A p.Ile323Thr mutant T2 was detected with relative enzyme activity and protein amount of 20% and 25%, respectively, compared with wild type at 37°C; it was more prevalent at 30°C but ablated at 40°C. These findings showed that p.Ile323Thr had a significant residual T2 activity with temperature-sensitive instability. Neither residual enzymatic activity nor mutant T2 protein was identified in p.Met193Arg, p.Ala215Asn, and c.1012_1015dup mutations using supernatants; however, these mutant T2 proteins were detected in insoluble pellets by immunoblot analysis. Expression analyses confirmed pathogenicity of these mutations. T2 deficiency has a likely high incidence in India and p.Met193Arg may be a common mutation in the Indian population.

Mutational Screening and Prenatal Diagnosis in Cornelia de Lange syndrome.

Phenotypic variability and the lack of a diagnostic marker have complicated the rapid diagnosis and genetic counseling for Cornelia de Lange syndrome (CdLS). The clinical features of CdLS are striking and easily recognizable by characteristic facial dysmorphism, upper-extremity malformations, hirsutism, cardiac defects, growth and cognitive retardation, and gastrointestinal abnormalities with severe mental retardation. The molecular diagnosis is essential for predicting prognosis and genetic counseling in the affected family, especially while planning the next pregnancy. We report here from India six cases of CdLS and how precise mutational screening in two cases helped in prenatal diagnosis and proved significant in prevention of recurrence in the affected family.

Brain-Derived Neurotrophic Factor in children with Autism Spectrum Disorder.

BACKGROUND: Autism Spectrum Disorder (ASD) is a complex neurobehavioral syndrome with no known biomarker so far for early detection. It has been challenging, both to classify typical autism and associate a suitable biomarker with clinical phenotype spectrum. Brain-derived neurotrophic factor (BDNF) has emerged as a key neurotrophin regulating synaptic plasticity, neuronal differentiation and survival. PURPOSE: Recently, BDNF depletion is reported in neurodegenerative as well as in psychiatric disorders, associated with severity of neurological dysfunction. Role of BDNF as a biomarker in ASD is gaining significance. Pre-clinical results have linked BDNF depletion in autism and mental retardation, however, with conflicting findings. METHODS: In view of this, a preliminary study was carried out to measure serum BDNF levels in 48 children with ASD and mental retardation, and 29 age-matched controls. RESULTS: Serum BDNF levels were found significantly higher (p<0.001) in atypical autistic subjects (clinically milder phenotype) as compared to controls, but not in typical ASD cases (clinically severe phenotype). BDNF levels were significantly lower in females with typical/Rett Syndrome (p<0.05), but not in males with typical autism (p>0.1), as compared to controls. Lower BDNF levels indicate impairment in neuroprotective mechanism, while higher levels may imply a manifested protective response. CONCLUSION: Our study highlights the differential BDNF response based on the severity of neurobehavioral deficit, indicating a possible neuroprotective role of this molecule and supporting its exploration in targeted therapy in ASD.

An open-label study to elucidate the effects of standardized Bacopa monnieri extract in the management of symptoms of attention-deficit hyperactivity disorder in children.

CONTEXT: Attention-deficit hyperactivity disorder (ADHD) is a clinically heterogeneous disorder of inattention, hyperactivity, and impulsivity or difficulty in controlling behavior. Psychostimulant medications remain the mainline treatment for children with ADHD; however, the average response rate to these medications is 70%, and up to 30% of children do not respond to these medications or are unable to tolerate such potential adverse effects as nausea, insomnia, and weight loss. OBJECTIVE: The study investigated the effectiveness of standardized Bacopa monnieri extract (SBME) in ameliorating the severity of the symptoms of ADHD in children. DESIGN: The clinical trial was conducted as an open-label study. SETTING: The study was conducted at the Center for Research in Mental Retardation (CREMERE) in Mumbai, India, from 2008 to 2010. PARTICIPANTS: Thirty-one children were participants in the trial. They were 6-12 y of age, with an age of onset of ADHD before 7 y of age, as defined by the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria for ADHD. INTERVENTION: The children received SBME at a dose of 225 mg/d for a period of 6 mo. The specific SBME used in the study was BacoMind (M/s Natural Remedies, Bangalore, India). OUTCOME MEASURES: Subsequent to the screening of participants, the research team administered the Parent Rating Scale to assess the ADHD symptom scores at baseline, and the team administered it again at the end of the 6 mo of treatment. RESULTS: SBME significantly reduced the subtests scores of ADHD symptoms, except for social problems. The symptom scores for restlessness were reduced in 93% of children, whereas improvement in self-control was observed in 89% of the children. The attention-deficit symptoms were reduced in 85% of children. Similarly, symptom scores for learning problems, impulsivity, and psychiatric problems were reduced for 78%, 67%, and 52% of children, respectively. It was observed that 74% of the children exhibited up to a 20% reduction, while 26% of children showed between a 21% and a 50% reduction in the total subtests scores. CONCLUSION: Standardized extract of B monnieri was found to be effective in alleviating the symptoms of ADHD and was well-tolerated by the children.

Plasma chitotriosidase activity in children with lysosomal storage disorders.

Chitotriosidase (ChT) is an enzyme that is selectively activated in tissue macrophage. This property of ChT makes it a potential marker for many disease process and prognostication. Present study has been carried out to know the significance of ChT as a screening marker in lysosomal storage disorders (LSDs) where tissue macrophage activation is commonly observed due to accumulation of substrate in various organs of the body. Study comprises of 20 healthy children in the age range of 10 days to 5 yrs and 56 children in the age range of 2.5 months to 13 yrs with regression of milestones, skeletal dysplasia, neuroregression and hepatosplenomegaly were selected for plasma ChT who had confirmed LSDs as carried out by specific lysosomal enzyme study from the leukocytes or fibroblasts. Plasma ChT was 55.21 +/- 20.81 nmol/ml/hr in twenty healthy age matched controls. Plasma ChT level was 42.88 to 79.78 nmol/ml/hr in thirteen of 56 (23.21%) children with LSDs like Morquio-B, Pompe, Metachromatic leucodystrophy (MLD), Sandhoff and Niemann-Pick disease type C (NPD-C). While in 43 (76.78%) children it was in the range of 213.74 to 23,511.40 nmol/ml/hr. who had LSDs like Morquio-B, Sly syndrome, MLD, GM2 Gangliosidosis, NPD-A/B and Gaucher disease (GD). Marked elevated ChT (4,000 to 23,511 nmol/ml/hr) was observed in all cases of GD (n=7) and NDP-A/B. It can be concluded from the present study that moderately raised activity of ChT can be utilized as a positive predictive test for certain LSD's. Those with marked elevated ChT have confirmed GD or NPD-A/B making it a strong screening marker for this group of diseases.