ABSTRACT
Background & objectives: Screening for Fragile X syndrome (FRAXA), the most common genetic cause for mental retardation (MR), has mostly been carried out among MR patients. The present study was conducted to find out prevalence of FRAXA amongst children residing in the rural areas of West Bengal. Methods: Demographic details including age, sex, nutritional status as well as birth, medical, and developmental histories, were collected amongst rural children (n=38,803) of West Bengal, India, over three years (2004-2007). Based on the records of scholastic backwardness, 179 children were short-listed and examined by a team of experts comprising of child psychiatrist, clinical psychologist, paediatrician and special educator. Blood samples were collected and molecular and cytogenetic studies were performed for identification of CGG repeats and determination of FMR1 gene promoter methylation. Results: Of the selected 179 children, six were diagnosed as Down syndrome, one as cerebral palsy and 140 as non-syndromic MR. These 140 children with MR were grouped as mild (56), moderate (60), and severely (4) retarded based on IQ; children <5 yr were grouped as developmental delay (20). FRAXA was not detected in any of these children (frequency being 0% with 0-.02% confidence interval). Prevalence of MR was found to be low (about 4/1000 children). Down syndrome also had a lower frequency (0.15/1000 children). Interpretation & conclusion: The data obtained in the present study indicated that familial disorders like FRAXA were less frequent in the studied population.
Subject(s)
Child , Child, Preschool , DNA Methylation , Female , Fragile X Mental Retardation Protein/genetics , Fragile X Syndrome/epidemiology , Fragile X Syndrome/genetics , Humans , India/epidemiology , Intellectual Disability/epidemiology , Intellectual Disability/genetics , Male , Mass Screening , Promoter Regions, Genetic , Rural Population , Trinucleotide Repeat ExpansionABSTRACT
OBJECTIVE: To study the association of Attention Deficit Hyperactivity Disorder (ADHD) and polymorphism in the dopamine beta hydroxylase (DBH) gene in Indian ADHD cases. SUBJECTS: Forty one ADHD cases were diagnosed as per the DSM-IV-TR criteria and evaluated by Conners Parents and Teachers Rating Scale and Wechslers Intelligence Scale for Children. METHODS: Genomic DNA was amplified for exon 2 *444g/a and intron 5 (Taq I) polymorphism in the DBH gene followed by restriction fragment length polymorphism (RFLP) analysis. Haplotype-based haplotype relative risk (HHRR) was analyzed to ascertain the transmission pattern of these two polymorphisms in ADHD cases. Linkage disequilibrium (LD) between the two polymorphisms was calculated using EH+ and 2LD programs. RESULTS: In the limited number of samples analyzed, a slight increase in transmission of the 444a allele in ADHD subjects was observed for DBH 444g/a. The intron 5 (Taq I) polymorphism showed no significant association with ADHD in these cases. Strong disequilibrium was observed between DBH444g/a and intron 5 (Taq I) polymorphism. CONCLUSION: This is the first molecular genetic study on ADHD in Indian subjects exploring transmission of polymorphisms in the DBH gene. Preliminary investigation shows a trend towards association between the transmission of DBH444a allele and ADHD. No association was noticed between transmission of intron 5 (Taq I) polymorphism and ADHD in the Indian subjects. Presence of strong LD may point towards co-segregation of these two polymorphisms more often than expected.