INHERITANCE: sporadic new autosomal dominant mutations


FREQUENCY: 1/35,000; the most common form of lethal neonatal dwarfism


CLINICAL: in utero hydrocephalus from cloverleaf (Kleeblattschadel) skull deformity; short limbs, long narrow trunk, marked midface hypoplasia;


RADIOGRAPHIC: platyspondyly, telephone receiver femora


PATHOLOGY: lack of organized cell physeal columns; "ossification tufts" of mineralization extend from subchondral bone


PROGNOSIS: death at or soon after birth from respiratory insufficiency


TREATMENT: none