Osteochondrodysplasias are skeletal disorders that cause malformations of both bone and cartilage.
Presentation
Prenatal and neonatal diagnosis of boomerang dysplasia includes several prominent features found in other osteochondrodysplasias, though the "boomerang" malformation seen in the long bones is the delineating factor.[2]
The characteristic "boomerang" malformation presents intermittently among random absences of long bones throughout the skeleton, in affected individuals.[3][6] For example, one individual may have an absent radius and fibula, with the "boomerang" formation found in both ulnas and tibias.[6] Another patient may present "boomerang" femora, and an absent tibia.[3]
Cause
Mutations in the Filamin B (FLNB) gene cause boomerang dysplasia.[1] FLNB is a cytoplasmicprotein that regulates intracellular communication and signalling by cross-linking the protein actin to allow direct communication between the cell membrane and cytoskeletal network, to control and guide proper skeletal development.[7] Disruptions in this pathway, caused by FLNB mutations, result in the bone and cartilage abnormalities associated with boomerang dysplasia.[citation needed]
Chondrocytes, which also have a role in bone development, are susceptible to these disruptions and either fail to undergo ossification, or ossify incorrectly.[1][7]
Early journal reports of boomerang dysplasia suggested X-linkedrecessiveinheritance, based on observation and family history.[3] It was later discovered, however, that the disorder is actually caused by a sporadic genetic mutation fitting an autosomaldominant genetic profile.[8]
Autosomal dominant inheritance indicates that the defective gene responsible for a disorder is located on an autosome, and only one copy of the gene is sufficient to cause the disorder, when inherited from a parent who has the disorder.[10]
Boomerang dysplasia, although an autosomal dominant disorder,[8] is not inherited because those afflicted do not live beyond infancy.[1] They cannot pass the gene to the next generation.[citation needed]
Diagnosis
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Treatment
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^Kozlowski K, Tsuruta T, Kameda Y, Kan A, Leslie G (1981). "New forms of neonatal death dwarfism. Report of 3 cases". Pediatr Radiol. 10 (3): 155–160. doi:10.1007/BF00975190. PMID7194471. S2CID31143908.
^Urioste M, Rodriguez JL, Bofarull J, Toran N, Ferrer C, Villa A (1997). "Giant-cell chondrocytes in a male infant with clinical and radiological findings resembling the Piepkorn type of lethal osteochondrodysplasia". Am J Med Genet. 68 (3): 342–346. doi:10.1002/(SICI)1096-8628(19970131)68:3<342::AID-AJMG17>3.0.CO;2-T. PMID9024569.
^ abcNishimura G, Horiuchi T, Kim OH, Sasamoto Y (1997). "Atypical skeletal changes in otopalatodigital syndrome type II: phenotypic overlap among otopalatodigital syndrome type II, boomerang dysplasia, atelosteogenesis type I and type III, and lethal male phenotype of Melnick-Needles syndrome". Am J Med Genet. 73 (2): 132–138. doi:10.1002/(SICI)1096-8628(19971212)73:2<132::AID-AJMG6>3.0.CO;2-W. PMID9409862.
^Greally MT, Jewett T, Smith WL Jr, Penick GD, Williamson RA (1993). "Lethal bone dysplasia in a fetus with manifestations of Atelosteogenesis type I and Boomerang dysplasia". Am J Med Genet. 47 (4): 1086–1091. doi:10.1002/ajmg.1320470731. PMID8291529.