Atypical amyoplasia congenita in an infant with Leigh syndrome: a mitochondrial cause of severe contractures?

Amyoplasia congenita is a distinct form of arthrogryposis with characteristic features including internally rotated and adducted shoulders, extended elbows, flexion, and ulnar deviation of the wrists, and adducted thumbs. Fetal hypokinesia, secondary to a variety of genetic conditions, neuromuscular disorders, and environmental agents, is associated with contractures. In order to increase our understanding of the phenotypic spectrum associated with SURF 1 deficiency, a common cause of mitochondrial respiratory chain complex IV deficiency and Leigh syndrome, we describe a now 6-year-old boy who presented in the neonatal period with amyoplasia congenita. His development was normal until age 10.5 months, at which time he developed severe hypotonia and choreoathetosis following an episode of viral gastroenteritis. Following the onset of neurological symptoms, he gradually developed severe kyphosis and lower limb contractures. Blood and cerebrospinal fluid lactate levels were elevated and head imaging showed characteristic features of Leigh syndrome. He was found to harbor two pathogenic heterozygous mutations in the SURF 1 gene. In this case, mitochondrial dysfunction and the resultant energy deficiency may have played a role in causing abnormal neuronal development during embryogenesis, causing arthrogryposis. A variety of mitochondrial respiratory chain complex deficiencies have been associated with contractures of varying severity. Therefore, mitochondrial disorders should be considered in the differential diagnosis of neonatal arthrogryposis, especially if other characteristic findings such as lactic acidemia or basal ganglia abnormalities are present.