A rare phenotype of congenital muscular dystrophy: 'Muscular dystrophy-dystroglycanopathy type B,1'

Mutations of the POMT-1 gene cause heterogeneous phenotypes characterized by combinations of muscle, central nervous system, cardiac and ophthalmic involvement. These phenotypes are 'Muscular dystrophy-dystroglycanopathy type A,1', 'Muscular dystrophy-dystroglycanopathy type B,1' and 'Muscular dystrophy-dystroglycanopathy type C,1'. Microcephaly, facial weakness and upper motor neuron findings were observed in a 3.5-year-old girl with congenital hypotonia history who presented with complaints of inability to walk and speak. It was learned that there was consanguinity between his parents, there was a death history of 2 siblings at 2 months and 8 months, and his uncle had psychomotor retardation. High creatine phosphokinase (CPK) level (7208 U/L) in biochemistry analysis and periventricular white matter hyperintensity in cranial magnetic resonance imaging (MRI). In the whole exome analysis, c.598G>C homozygous mutation was detected in exon 7 of the POMT1 gene. Because of facial weakness, absence of ophthalmic involvement and cranial MRI findings, our patient was evaluated as compatible with the 'muscular dystrophy-dystroglycanopathy type B,1' phenotype. Dystroglycanopathies should be considered in patients with psychomotor retardation, microcephaly, upper motor neuron findings, elevated CPK levels accompanying ophthalmic and cardiac pathologies, and white matter involvement in cranial MRI. Dystroglyconapathies have a wide genetic and clinical heterogeneity, and the genotype-phenotype relationship is not clear. It is difficult to make a definitive diagnosis clinically in these patients. Therefore, whole exome analysis has an important place in the diagnosis.
Keywords: Dystroglyconapathy, muscular dystrophy, POMT1, congenital hypotonia, high creatine phosphokinase level