This points not only to a primary relationship of these symptoms with SMN deficiency, but also towards the possibility of their use in predicting time to neuromuscular symptom onset for treatment initiation prior to irreversible nervous system damage in later stage patients who may not have been screened at birth or who want to delay treatment while they remain asymptomatic. Here, SMN2 is linked to hyperinsulinemic hypoglycemia, familial, 4.