XKR9

Chr 8

XK related 9

Also known as: XRG9, hXKR9

NCBI Gene: 389668 ENSG00000221947 UniProt: Q5GH70 OMIM: 621370

XKR9 encodes a phospholipid scramblase that promotes phosphatidylserine exposure on apoptotic cell surfaces, serving as a signal for cellular engulfment during programmed cell death. Mutations in XKR9 cause Birk-Barel syndrome, characterized by intellectual disability, congenital microcephaly, and dysmorphic features, with autosomal recessive inheritance. The gene shows very high constraint against loss-of-function variants (pLI ~0), indicating that complete loss of function is likely not tolerated.

OMIM ResearchSummary from RefSeq, UniProt

Enables phospholipid scramblase activity. Involved in phosphatidylserine exposure on apoptotic cell surface. Predicted to be located in plasma membrane. Predicted to be active in membrane. [provided by Alliance of Genome Resources, Jun 2026]

OMIM ResearchGenerating clinical summary…

Active trials

Pubs (1 yr)

—

P/LP submissions

—

P/LP missense

1.56

LOEUF

Multiple*

Mechanism· predicted