A novel sporadic 614-Kb duplication of the 22q11.2 chromosome in a child with amyoplasia

Arthrogryposis is a rare congenital disorder characterized by multiple fixed joint contractures. Decreased fetal movement, regardless of etiology, causes an immobilization of the affected joints and subsequent contractures. Amyoplasia refers to the most common variant of arthrogryposis in which patients develop symmetrical limb contractures because of muscle underdevelopment. It is a sporadic condition with no known genetic abnormality being linked to this syndrome. The authors report a 4-month-old boy with amyoplasia carrying a novel de novo 614-Kb duplication of the 22q11.2 region. Amyoplasia has not been reported in patients with 22q11.2 microduplication syndrome. This particular 614-Kb duplicated segment contains 7 genes located within the typical 22q11.2 duplication region and 2 genes, TUBA8 and USP18, mapping outside of the typical region. This patient broadens the phenotypic spectrum of the 22q11.2 microduplication syndrome and raises the possibility that TUBA8 and USP18 may play an important role in the pathogenesis of amyoplasia.