RESUMO
Spinal muscular atropies are common [genetically determined] disorders. They are heterogeneous both in genetic and phenotypic characteristics. Prevalence of disease was reported between 1 in 6000 to 1 in 25000 in different populations. So, carrier frequency should be 1 in 40 to 1 in 80 in those people. Deletion of both copies of SMA, gene was detected in more than%90 of SMA patients. According to present data there were not any epidemiological study and data in Iran regarding SMAs. So, we do not have accurate information about prevalence, incidence of disease and its carrier frequency. Because of high rate of consanguinity it should be high. With this background, we decided to carry this pilot study out, to determine prevalence, incidence, carrier rate, along with consanguinity rate, clinical spectrum, and molecular abnormality in the affected cases. In a 2 years period, 30734 live-born babies followed, 4 patient affected to SMA type I were detected. Prevalence of SMA I in this population was 1 in 7683, and carrier frequency was 1 in 43. At least 2 third of the newborn babies were product of consanguineous marriages