Carrier frequency of SMA by quantitative analysis of the SMN1 deletion in the Northern-Cyprus population

Spinal muscular atrophy (SMA) is a rare autosomal recessive neuromuscular disorder, affecting approximately one out of 10,000 live births. Muscular atrophy is caused by the gradual loss of alpha motor neurons within the ventral spinal cord or motor nuclei in the lower brainstem. In this study, we aimed to evaluate the carrier frequency of SMN1 gene mutation causing SMA in the Turkish Cypriot population.

This is the first study to evaluate the SMN1 deletion mutations in this population. Exon 7 and 8 deletions of the SMN1 gene, and c.849C/T substitution within exon 7 were detected by Quantitative Real-Time PCR (RT-qPCR) method.

In a total of 100 individuals, 3 patients turned out to be carriers of the pathogenic SMN1 gene variant in both exon 7 and 8 (carrier status type 1) and another patient (Carrier status type 2) showed a car- rier status of SMN1 gene only in exon 7. Our findings revealed that the carrier frequency of mutation in the SMN1 gene exon 7 is 4% (4:100 healthy individuals) while for exon 8 is 3% (3:100 healthy individuals). In conclusion, health precautions must be taken due to the high frequency of SMA linked to the deletion of the SMN1 gene.

Carrier testing as a technique for genetic counseling may be advantageous for individuals with a positive family history or can even be a useful test in a society with a high prevalence of this disease. For this population, we strongly recommend prenatal testing. The Ministry of Health has received our findings, and they will decide whether to include tests for the SMN1 gene variant in premarital examinations.