SMN2 and spinal muscular atrophy: 5q‐linked spinal muscular atrophy (SMA) is an autosomal‐recessive motor neuron disease caused by mutations in the survival of motor neuron (SMN)1 gene with retained function of a paralogous SMN2 gene, resulting in a loss of functional SMN protein and consecutive degeneration of motor neurons in the ventral horn [1, 2].