We report three Tunisian patients affected by congenital
muscular dystrophy with
mental retardation and cerebellar
cysts on cranial magnetic resonance imaging. The clinical features were characterized by
hypotonia at birth, joint
contractures associated with severe psychomotor retardation, absence of speech, inability to walk in three patients, but calf
hypertrophy was noted only in two patients. Brain magnetic resonance imaging showed several cerebellar
cysts and vermis hypoplasia in all of the patients. Abnormality of the white matter was present in two patients. The pattern of gyration was normal in all cases. Serum
creatine kinase was elevated in all three cases and their muscle biopsy showed dystrophic changes compatible with congenital
muscular dystrophy. The immunohistochemical analysis of the skeletal muscle revealed partial
merosin deficiency, more pronounced for the N-terminal antibody. Linkage analysis excluded congenital
muscular dystrophy loci on chromosomes 6q22, 9q31, 1p32 and 1q42. These patients constituted a particular form of congenital
muscular dystrophy with a combination of severe motor delay,
mental retardation, partial
merosin deficiency and cerebellar
cysts. Two patients showed white matter abnormalities on magnetic resonance imaging and
hypertrophy of the calves. These cases, in addition to those reported previously, confirmed the large phenotypic variability in the group of secondary
merosin deficiency congenital
muscular dystrophy.