Congenital rapidly fatal form of nemaline myopathy with fetal hydrops and arthrogryposis. A case report and review.

A new lethal case of nemaline myopathy is reported. The diagnosis was made by postmortem muscle biopsy. The child died before his first day of life. This is one of the very rare cases of nemaline myopathy with severe antenatal ultrasonographic signs: fetal hydrops and arthrogryposis. In a review of the literature other cases of the congenital rapidly fatal form are found, some of them with clinical decrease of fetal movements but only few authors report ultrasonographic signs. The diagnostic, histopathogenic, genetic and evolutive aspects of this heterogeneous disorder are analyzed. This congenital nonprogressive myopathy is not as benign as previously thought and may be an etiology of the lethal form of arthrogryposis multiplex congenita. The existence of ultrasonographic antenatal signs seems to be a factor of poor prognosis. In spite of recent genetic discoveries, there is at present no specific antenatal diagnosis. Consequently, muscle biopsy in lethal cases is very important to allow a genetic counselling; however, in utero fetal biopsy has never been performed in such cases.