SMN2 and proximal spinal muscular atrophy: In a recent study from the German SMA Newborn Screening Model Projects, we were able to demonstrate that a notable proportion of SMA patients with 4 SMN2 copies (5 of 7 patients, all subjects investigated under the age of 5) developed the disease between 1.5 and 4 years, with the majority experiencing very subtle symptoms [17], but some individuals suffering from significant and irreversible motor regression.