SMN2 and spinal muscular atrophy, type II: Among the 23 confirmed cases, 8 patients had two SMN2 copies (all classified as SMA type 1), 11 patients had three SMN2 copies (including 4 with SMA type 1, 2 with SMA type 2, 3 with SMA type 3, and 2 asymptomatic cases), and 4 patients had four SMN2 copies (all asymptomatic).