Genetic and cytogenetic screening of autistic spectrum disorder: Genotype-phenotype profiles

Autism, a pervasive developmental disorder typically characterized by repetitive behaviour, social skills deficit (or a deficit in social communication), speech and language impairments. Our prime focus is to analyze the clinical features and phenotypical behavioural changes using the diagnostic and statistical manual of mental disorders, fourth edition, text revision (DSM IV-TR), and locating the biomarkers associated with specific autistic characters using karyotyping and fluorescence in situ hybridization (FISH) techniques. The prevalence rate of the neurexin 1 (NRXN1) gene polymorphism was also assessed in the current study. The study group involved 196 samples with 98 autistics, and equal age-matched (±2) controls based on their birth order and carrier. The participants include 35.2% males (n = 69) and 14.8% females (n = 29). The autistic and control participants were categorized based on their ages as group I (<12 yrs) with n = 62; males n = 41 (20.9%); females n = 21 (10.7%) and group II (≥12 yrs)-n = 36; males n = 28 (14.2%); females n = 08 (4.08%). Karyotyping was done for autism participants (n = 98) and the results showed that 90% of autistic participants were either the only child or the first child with a low perception and frequency in both the groups. Subsequently, we carried out the FISH assay on participants (n = 37) with higher DSM-IV TR score (≥30). Only 30 FISH tests were negative for subtelomeric deletions with NRXN1 polymorphism genotypic frequency as 62.50%, 25% and 25% for A/A, A/G and G/G genotype respectively. Our study suggests the link between a haplotype with clinical signs of autism for the single nucleotide sequence (SNP rs9636391) and links autistic characters and gene among autistic children according to their birth order, age and gender in India.