Cytopenia - NOT Fanconi anaemia

Gene: FAS

Green List (high evidence)

The rating of this gene has been updated to green and the mode of inheritance updated to BOTH monoallelic and biallelic, autosomal or pseudoautosomal following NHS Genomic Medicine Service approval.

Created: 10 Dec 2025, 3:27 p.m. | Last Modified: 10 Dec 2025, 3:27 p.m.

Panel Version: 4.30

Comment on list classification: There is sufficient evidence available for the association of both monoallelic and biallelic variants with autoimmune cytopenia. Hence, this gene can be promoted to green rating in the next GMS update.

Created: 19 Jun 2025, 9:53 a.m. | Last Modified: 19 Jun 2025, 9:53 a.m.

Panel Version: 4.5

FAS has a well-established gene-disease association for autoimmune lymphoproliferative syndrome (ALPS). Both germline and somatic variants have been reported to cause ALPS.

FAS has been associated with autosomal dominant ALPS in OMIM (MIM #601859) and Gene2Phenotype (with 'definitive' rating on 'Skin disorders' panel). OMIM also reports autoimmune hemolytic anemia, thrombocytopenia and neutropenia as clinical presentations of this disorder.

This gene has also been associated with autosomal recessive ALPS syndrome in Gene2Phenotype (with 'definitive' rating on 'Skin disorders' panel).

PMID:34171534 reviewed evidence from previously published reports, which showed that there is sufficient evidence available for the association of both monoallelic and biallelic germline variants with ALPS syndrome. There is also sufficient evidence available for the presence of autoimmune cytopenias (hemolytic anemia, thrombocytopenia and neutropenia) in both patients with both monoallelic and biallelic variants.

Created: 19 Jun 2025, 9:51 a.m. | Last Modified: 19 Jun 2025, 9:58 a.m.

Panel Version: 4.5

Mode of inheritance
BOTH monoallelic and biallelic, autosomal or pseudoautosomal

Phenotypes
Autoimmune lymphoproliferative syndrome, type IA, OMIM:601859

Publications

• 34171534

Green List (high evidence)

FAS pathogenic variants (germline or somatic) causes ALPS, which has a complex phenotype including different cytopenias (mostly autoimmune).
Sources: Other

Created: 13 Oct 2024, 8:56 a.m.

Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted

Phenotypes
ALPS