Limb disorders

Gene: FAM92A

Green List (high evidence)

Comment on phenotypes: OMIM phenotype updated 11th May 2026.

Created: 11 May 2026, 2:40 p.m. | Last Modified: 11 May 2026, 2:40 p.m.

Panel Version: 8.5

Comment on list classification: There are now 2 unrelated families with biallelic FAM92A (CIBAR1) variants and non-syndromic postaxial polydactyly. A mouse knockout model showed abnormal digit morphology, which supports this gene-phenotype association. Based on available evidence, this gene can be promoted to Green at the next update.

Created: 11 May 2026, 2:39 p.m. | Last Modified: 11 May 2026, 2:39 p.m.

Panel Version: 8.4

ADDITIONAL CASE:
PMID: 38853702 Umair et al., 2024
Report of an individual homozygous for FAM92A: c.472G>C; p.Ala158Pro variant, with non-syndromic postaxial polydactyly. Seq method: WES. Variant is not reported in gnomAD v4.1.1. Consanguineous parents, both heterozygous unaffected.

Created: 11 May 2026, 2:36 p.m. | Last Modified: 11 May 2026, 2:39 p.m.

Panel Version: 8.4

Added new-gene-name tag, new approved HGNC gene symbol for FAM92A is CIBAR1.

Created: 11 May 2026, 2:31 p.m. | Last Modified: 11 May 2026, 2:31 p.m.

Panel Version: 8.3

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
?Polydactyly, postaxial, type A9, OMIM:618219; polydactyly, postaxial, type A9, MONDO:0032603

Publications

• 38853702

I don't know

Comment on list classification: Promoted from red to amber. 1 case plus a mouse knockout showing a similar phenotype.

Created: 7 Aug 2019, 3:38 p.m. | Last Modified: 7 Aug 2019, 3:38 p.m.

Panel Version: 1.53

Provisionally associated with ?Polydactyly, postaxial, type A9 (#618219) in OMIM.

PMID: 30395363 - Schrauwen et al. 2018 - 1 case. They report a consanguineous Pakistani family with 3 children with autosomal recessive nonsyndromic postaxial polydactyly type A with a homozygous nonsense variant (NM_001283034.1:c.478C>T, NP_001269963.1: p.[Arg160*]) in the FAM92A gene. It was confirmed that this variant segregates with PAPA. The c.478C>T variant (rs368652620) was observed in the gnomAD database with a very low MAF in the exome data (all populations MAF=2.04×10−5, South East Asians MAF=6.55×10−5 and no homozygous individuals observed and ) and was also not present in Sanger sequence data from 186 in-house control Pakistani DNAs. In mouse studies, FAM92A is expressed in the developing mouse limb and Fam92a−/− homozygous mice also exhibit an abnormal digit morphology, including metatarsal osteomas and polysyndactyly, in addition to distinct abnormalities on the deltoid tuberosity of their humeri.

Created: 7 Aug 2019, 3:37 p.m. | Last Modified: 26 Nov 2019, 12:59 a.m.

Panel Version: 1.126

Sources: Literature

Created: 7 Aug 2019, 1:18 p.m.

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
postaxial polydactyly type A9

Publications

• 30395363