Association of serotonin transporter gene polymorphisms with obsessive-compulsive disorder (OCD) in a south Indian population.

BACKGROUND AND OBJECTIVES: Serotonin transporter polymorphisms, 5-HTTVNTR and 5-HTTLPR, have been found to be associated with obsessive-compulsive disorder (OCD) and particularly with neurotic characteristics. In the present study we looked for an association between OCD and these polymorphisms in OCD patients and controls of south Indian origin. METHODS: 5-HTTVNTR and 5-HTTLPR/rs25531 were genotyped in 93 OCD patients and 92 healthy controls. The allelic distribution and genotype frequency in cases and controls were compared using chi square test. In order to test for the effects of genotype on heterogeneity of the illness, linear regression analysis was undertaken for co-morbid depression status and YBOCS score (severity index). RESULTS: There was no significant association with the 5-HTTVNTR or the 5-HTTLPR polymorphism. No significant association of OCD with the 5-HTTLPR genotype was found even on inclusion of the rs25531 locus, which is part of the transcription factor binding site as reported in earlier studies. However, severity of the illness showed a modest association with the dominant model. INTERPRETATION AND CONCLUSIONS: Our data show that genetic variation in the SLC6A4 gene regulatory region may not have a significant effect on OCD in the present population. Further replication in a large and independent cohort with an equal number of female subjects would help to ascertain if the absence of association in this cohort is due to the nullifying effect of the larger proportion of male subjects in our sample population. The marginal effect of the 5-HTTLPR (A/G) genotype obtained on linear regression with disease severity is suggestive of a potential role for this locus in the disease process.

Duchenne muscular dystrophy: a clinical, histopathological and genetic study at a neurology tertiary care center in Southern India.

BACKGROUND: Duchenne muscular dystrophy (DMD) is the most common muscular dystrophy that affects young boys and the dystrophin gene on the X chromosome has been found to be associated with the disorder. MATERIALS AND METHODS: In this prospective study, 112 clinically diagnosed DMD patients had muscle biopsy and were tested for exon deletions. Genotyping was also carried out at STR44, STR45, STR49 and STR 50 markers in 15 families. RESULTS: Of the 112 clinically suspected DMD patients, the diagnosis of DMD was confirmed by histopathology and/or genetics in 101 patients. The mean age of onset was 3.1+/-1.44 years (1-6 years) and the mean age at presentation was 8.0+/-3.1 years (1.1-18.0 years). Delayed motor milestones were present in 63 (62.3%) patients. The mean creatine kinase value was 11822.64+/-8206.90 U/L (1240-57,700). Eighty-four patients had muscle biopsy and immunohistochemistry was done in 60 muscle samples, all of which demonstrated absence of dystrophin staining. Of the 60 dystrophin-negative cases, 73% showed deletion of at least one exon. Single exon deletion was found in 20.4%. Distal hotspot Exons 45, 47, 49 and 50 were the commonly deleted xenons and the deletion rates were 36%, 35%, 33.7% and 38.5% respectively. CONCLUSIONS: In this study population in south India the deletion rate was 73% and were more frequent in the distal end exon. With the availability of genetic analysis, the first investigation of choice in DMD should be genetic studies and muscle biopsy should be considered only if the genetic tests are negative or not available.

Paternal inheritance or a de novo mutation in a Duchenne Muscular Dystrophy pedigree from South India.

A six year old boy presented with classical features of Duchenne Muscular Dystrophy (DMD) and was confirmed by absent dystrophin staining on muscle biopsy. In the paternal line there were 5 affected individuals across two generations with classical DMD. There was no family history of the illness in the maternal line. Molecular genetics analysis by PCR of the exons showed a deletion in exon 45 in two affected individuals. Microsatellite analysis showed that though the deletion was observed in the same locus in exon 45 it is a new independent mutation.