An incidental finding in an infertile man with SMNc deletion Is there any correlation to infertility

Spinal muscular atrophy, an autosomal recessive disease, is characterized by muscle weakness and atrophy. SMA is caused by the deletion of SMNt gene located on chromosome 5q13 (part of a 500kb inverted duplication). There are two SMN genes in this locus, telomeric (SMNt) and centromeric (SMNc) copy genes. Increases in SMNc copy number often modify the SMA phenotypes. Here we report an infertile man, referred to our lab for microdeletion testing in AZF regions. The results of microdeletion were negative. Clinical examination showed no serious typical phenotypes related to SMA. We incidentally found a homozygous deletion of exons 7 and 8 of SMNc gene, using his DNA as a control sample with samples of SMA patients. Although homozygous deletion of exons 7 and 8 of the SMNc is present in approximately 5% of the normal population, there are some cases of lower motor neuron disease with homozygous (SMNc) deletion. Interestingly, it is determined that SMN expression in testis is high. It was also reported that a mouse model of SMN C/C which expresses a reduced amount of SMN (~25–50% of WT) displayed a mild SMA-like phenotype, including peripheral necrosis, autonomic nervous system dysfunction, reduced testis size and impaired spermatogenesis. As a result we would hypothesize that impaired spermatogenesis that caused infertility may have a correlation with the SMNc homozygous deletion in the patient. To confirm this correlation more evidences and further studies of SMNc deletion in infertile patients are needed.

کلیدواژه ها:

SMA ، SMNc ، SMN2 gene ، Infertility ، MLPA ، Incidental finding