Nemaline myopathy : A family with probable recessive inheritance

Abstract

Nemaline myopathy is one of the congenital ultrastructural myopathies. While many sporadic cases have been reported, it is said that the most likely pattern of inheritance is by autosomal dominant gene with variable penetrance resulting in variable clinical manifestations. Mild or subclinical cases in a family can easily be missed. The index case in this family was a 6 week old infant with severe hypotonia from birth. Muscle biopsy established a diagnosis of nemaline myopathy. With a view to aiding in genetic counselling, the parents each had a muscle biopsy. In father’s biopsy, very occasional fibres with “rod bodies” were seen, while in mother’s biopsy there was patchy disruption of the Z-band. It was concluded that i) there was a strong possibility of recessive inheritance in this family, ii) if dominant inheritance was responsible, then father was the gene carrier. The child died of respiratory failure at two years of age. Permission for autopsy was not able to be obtained. A second pregnancy following artificial insemination produced a normal child. Until the gene for nemaline myopathy is localised, muscle biopsy of apparently asymptomatic parents may help in genetic counselling and further pregnancy planning. Nemaline myopathy is one of the congenital ultrastructural myopathies. While many sporadic cases have been reported, it is said that the most likely pattern of inheritance is by autosomal dominant gene with variable penetrance resulting in variable clinical manifestations. Mild or subclinical cases in a family can easily be missed. The index case in this family was a 6 week old infant with severe hypotonia from birth. Muscle biopsy established a diagnosis of nemaline myopathy. With a view to aiding in genetic counselling, the parents each had a muscle biopsy. In father’s biopsy, very occasional fibres with “rod bodies” were seen, while in mother’s biopsy there was patchy disruption of the Z-band. It was concluded that i) there was a strong possibility of recessive inheritance in this family, ii) if dominant inheritance was responsible, then father was the gene carrier. The child died of respiratory failure at two years of age. Permission for autopsy was not able to be obtained. A second pregnancy following artificial insemination produced a normal child. Until the gene for nemaline myopathy is localised, muscle biopsy of apparently asymptomatic parents may help in genetic counselling and further pregnancy planning.