Limb disorders

Gene: B9D2

Comment on list classification: Gene made grey as it is green on the Rare multisystem ciliopathy disorders panel (v1.78) and the ciliopathy panel will be applied if a patient is suspected of having a ciliopathy, or the possibility of a ciliopathy cannot be excluded.

Created: 2 Dec 2018, 10:38 p.m.

Comment when marking as ready: Marked as ready after reviewing the available evidence

Created: 16 Oct 2018, 3:17 p.m.

Comment on list classification: Rating as red as only 1 variant reported in 1 family in association with Meckel syndrome 10.

Created: 3 Oct 2018, 1:54 p.m.

In OMIM B9D2 is provisionally associated with ?Meckel syndrome 10 and is associated with Joubert syndrome 34.

Dowdle et al. (2011)(PMID: 21763481) report 2 fetuses from the same fifth degree consanguineous family with Meckel syndrome-10 with a homozygous mutation in the B9D2 gene (S101R). Phenotypes of both fetuses included polydactyly. They also report functional studies that show the p.Ser101Arg mutation abrogates the ability of B9d2 to interact with Mks1, further suggesting that the mutation compromises B9d2 function.

A PubMed search did not find any other cases of B9D2 variants in individuals with Meckel syndrome.

Bachmann-Gagescu et al. (2015) (PMID: 26092869) identified homozygous or compound heterozygous mutations in the B9D2 gene in 2 unrelated patients with Joubert syndrome. The mutations were identified by sequencing 27 candidate genes in 428 affected individuals from 363 families. Neither patient showed limb disorders relevant to this panel although one had tibial and fibular mesomelic dysplasia (Supplementary Table S7).

Created: 3 Oct 2018, 1:51 p.m.