Spinal Muscular Atrophy with congenital Bone Fractures 2 (SMABF2) [MIM: 616867] is a very rare and severe neuromuscular disorder characterized by congenital joint contractures (consistent with arthrogryposis multiplex congenita), and multiple congenital fractures of the long bones. The disease has onset in utero or at birth and in prenatal life reduced or absent fetal movements, fetal hypokinesia, polyhydramnios and sometimes fetal hydrops may be found. Additional manifestations are severe muscle hypotonia and neonatal respiratory distress. Facial dysmorphism, cardiac and neurological abnormalities are found more rarely.To date, only 15 cases have been described and the exact prevalence is unknown. SMABF2 is caused by a defect in the ASCC1 gene and is transmitted in an autosomal recessive manner, i.e. both parents are healthy carriers of the genetic defect and have a 25% chance of transmitting the disease to each of their children.
ASCC1