Boomerang Dysplasia

A number sign (#) is used with this entry because of evidence that boomerang dysplasia (BOOMD) is caused by heterozygous mutation in the FLNB gene (603381) on chromosome 3p14.

Clinical Features

Kozlowski et al. (1981), Tenconi et al. (1983), and Kozlowski et al. (1985) each described 1 patient with a disorder termed boomerang dysplasia because of the unusual shape of the long bones of the legs. All 3 patients died in the neonatal period. They had dwarfism with short, bowed, rigid limbs and characteristic facies. In particular, the nose had a broad root and severe hypoplasia of the nares and septum. Radiographically, the radii and fibulae were absent, while the remaining long bones had the boomerang configuration. The iliac bodies were small and ossification in the lower spine and digits was retarded. All 3 patients were males, from Japan, Italy, and Australia. Winship et al. (1990) described a fourth patient, again a male infant. Shortened boomerang-shaped radii, femora, and tibias were noted. The vertebral borders showed coronal clefts.

Hunter and Carpenter (1991) described a patient with apparent manifestations of both type I atelosteogenesis (108720) and boomerang dysplasia and concluded that these disorders are 'part of a spectrum, probably reflecting a common etiology.' Greally et al. (1993) presented a case that supported the hypothesis of Hunter and Carpenter (1991).

Urioste et al. (1997) reported a possible case of boomerang dysplasia in the offspring of healthy, nonconsanguineous parents. Delivery was induced at 27 weeks of gestation. He was markedly disproportionate with a large head, very short and flipper-like limbs, numerous malformations, and generalized alopecia. Radiologic skeletal examination showed generalized underossification. The pubic bones were absent. Only one well-ossified and bowed bone was observed in the legs, which had the appearance of a boomerang. Histologic studies showed multinucleated giant chondrocytes in the cartilage. The karyotype was apparently normal.

Odent et al. (1999) reported a female fetus of 24 weeks' gestation with clinical and radiologic features compatible with boomerang dysplasia. Histopathology, however, showed unusual lateral fan-shaped diaphyseal ossification. Odent et al. (1999) concluded that these features represented a variant of boomerang dysplasia with clinical characteristics of both atelosteogenesis type I and boomerang dysplasia.

Wessels et al. (2003) reported a male fetus with boomerang dysplasia that was diagnosed by ultrasound at 16 weeks of gestation. Delivery was induced at 17 weeks of gestation; postdelivery examination revealed dwarfism and micromelia of the 4 limbs. In each limb only 1 of the 3 long tubular bones was ossified; the presumed radius had a boomerang shape and the presumed tibia had a segment shape. The hands and feet were very short and broad with severe brachydactyly. The ossification centers of all vertebrae except for T11-12 and L1-3 were absent. The thorax was small and bell-shaped with short ribs. The skull showed micrognathia.

Molecular Genetics

In a 22-week male fetus previously studied by Krakow et al. (2004) and a 17-week male fetus previously described by Wessels et al. (2003), both diagnosed with boomerang dysplasia, Bicknell et al. (2005) identified heterozygosity for mutations in the FLNB gene, leu171 to arg (L171R; 603381.0009) and ser235 to pro (S235P; 603381.0010), respectively.