Skeletal muscle MRI of the lower limbs in congenital muscular dystrophy patients with novel POMT1 and POMT2 mutations

Abstract

Alpha-dystroglycanopathies form a genetically heterogeneous group of congenital muscular dystrophies with a large variety of clinical phenotypes. Within this group mutations in the protein O-mannosyltransferase genes (POMT1 and POMT2) are known to cause a spectrum of CMD disorders including the Walker–Warburg Syndrome with severe brain and ocular malformations, and the limb girdle muscular dystrophy with and without mental retardation. In this case report the clinical phenotype and brain and muscle MRI findings of two siblings of 10 and 7years (male/female) homozygous for a novel mutation in the POMT1 gene (c.2220G>C, p.Trp740Cys) and a 10year old boy with two novel mutations in the POMT2 gene ((c.215G>A, p.Arg72His) and (c.713G>T, p.Gly238Val) are presented. Mutation detection was performed by direct sequencing of the FKRP, FKTN, POMT1 and POMT2 genes. T1-weighted axial muscle MRI of the lower limbs revealed diffuse fatty degeneration of thigh and calf muscles with predominance of gluteus maximus, adductor magnus, posterior thigh, medial gastrocnemius, and peroneus muscles, but no edematous changes. As a similar pattern of muscle involvement had been described in FKRP related α-dystroglycanopathy LGMD2I, we conclude that α-dystroglycanopathies may present with distinctive muscle MRI changes.