Exp Mol Med.  2005 Jun;37(3):147-154.

Genotype-Phenotype correlation of SMN locus genes in spinal muscular atrophy patients from India

• Kesari A
• Idris MM
• Chandak GR
• Mittal B

Abstract

Spinal muscular atrophy has been classified into four groups based on the age of onset and clinical severity of the disease. Homozygous deletion in SMN1 gene causes the disease but the clinical severity may be modified by copy number of homologous gene SMN2 as well as the extent of deletion at SMN locus. In the view of scarcity of genotype and phenotype correlation data from India, this study has been undertaken to determine that correlation in SMA patients by using the SMN and NAIP genes and two polymorphic markers C212 and C272 located in this region. Two to four alleles of the markers C212 and C272 were observed in normal individuals. However, majority of Type I patients showed only one allele from both markers whereas in Type II and III patients, 2-3 alleles were observed. The SMN2 copy number in our type III patients showed that patients carry 3-5 copies of SMN2 gene. Our results suggest that extent of deletions encompassing H4F5, SMN1, NAIP and copy number of SMN2 gene can modify the SMA phenotype, thus accounting for the different clinical subtypes of the disease.

Keyword

C212; C272; NAIP; SMN1; SMN2

MeSH Terms

Adolescent
Adult
Alleles
Apoptosis
Child
Child, Preschool
Chromosomes, Human, Pair 5/*genetics
Comparative Study
DNA Mutational Analysis
DNA-Binding Protein, Cyclic AMP-Responsive/*genetics
Enzyme Inhibitors/metabolism
Female
Gene Deletion
*Genetic Markers
Genotype
Homozygote
Humans
India
Infant, Newborn
Male
Muscular Atrophy, Spinal/*genetics/pathology
Nerve Tissue Proteins/*genetics
Phenotype
RNA-Binding Proteins/*genetics
Variation (Genetics)