A genetic study revealed an apparent homoplasmic T>C substitution at nucleotide position 9185, in MTATP6, that replaces a highly conserved leucine to proline at codon 220 (p.L220P); the genetic study of SMA did not detect any homozygous deletion in exon 7 or heterozygosity of exons 7 and 8, in the SMN1 gene. The gene discussed is SMN1; the disease is proximal spinal muscular atrophy.