Bi-allelic variants cause LCCS9, the key features are reduced fetal movements and arthrogryposis, presenting as early as 18 weeks gestation. Other features include talipes, rockerbottom feet, narrow thorax, gracile bones, reduced muscle bulk, pulmonary hypoplasia and micrognathia. As with our cases of fetal akinesia, the pregnancy can be complicated by polyhydramnios, in some cases requiring amnioreduction.
Muscle at autopsy showed a diffuse non-specific myopathic process in one case. Variation in myofibre size, patchy-group atrophy and increased central nuclei were also noted. There was no obvious reduction in the amount of motor neurons in the anterior horns of the spinal cord.