Molecular characteristics
The FAM149B1 (Family With Sequence Similarity 149, Member B1) gene is located at 10q22.2 and encodes a protein of unknown function and is ubiquitously expressed in human tissues, especially in kidneys, testes, and ovaries.
Mutations and pathophysiology
Shaheen et al. (2019) observed cilia-related abnormalities in FAM149B1 mutant fibroblasts, including abnormal accumulation IFT-88 and IFT-46 (members of the IFT-B complex involved in the anterograde transport of cargo in the cilium) at the distal tips of the cilia with apparent assumed bulbous morphology (likely representing impaired retrograde transport), increased length of the primary cilium, and dysregulated SHH signalling.
Shaheen et al. (2019) reported two independent homozygous truncating mutations NM_173348.1; c.356_357del (p.Lys119Ilefs*18) and NM_173348.1; c.439C>T (p.Gln147*) in FAM149B1 in four families with phenotypical features along the spectrum of Joubert syndrome and oral-facial-digital syndrome (OFD VI).