MODEL RELEASED. Kugelberg-Welander disease. Man in a wheelchair. He has Kugelberg-Welander disease, a form of spinal muscular atrophy (SMA). SMA is the degeneration of motor neurones in the anterior horn of the spinal cord. Kugel-Welander disease (also known as Type III SMA) is an autosomal recessive disorder which begins during adolescence. Sufferers experience progressive weakness and wasting of proximal muscles, often losing the ability to walk.