SMN1 and spinal muscular atrophy, type 1: The clinical diagnosis was SMA, a progressive neuromuscular disease thatresults in muscle weakness due to deterioration and loss of the anterior horn cells.It is inherited in an autosomal recessive manner due to mutations in the SMN1 gene.In the most common and severe form, SMA type 1, death occurs due to respiratoryfailure before 2 years of age.