Bone Marrow Failure

Gene: TYMS

I don't know

Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted

Phenotypes
Dyskeratosis congenita, digenic, MIM#620040

Red List (low evidence)

8 families with dyskeratosis congenita and heterozygous variants in TYMS. 4 PTCs, 2 missense and 1 splice (2 families had the same frameshift). However in all families 1 unaffected parent was also heterozygous for the same TYSM variant.

The other parent in 3 of these families was then shown to carry a heterozygous variant in ENOSF1 which each affected child was also heterozygous for. ENOSF1 has been shown to modify TYMS expression at the RNA level by acting as an antisense molecule to TYMS. ENOSF1 partially overlaps TYMS on chromosome 18 and is transcribed in the opposite direction to TYMS. This paper is suggesting digenic inheritance.

The TYMS wild type parent from another family was seen to have a TYMSOS variant which was also observed along with the TYMS variant in their 2 affected children.

Immunoblotting showed a stark reduction in TYMS protein level in the cells of affected probands when compared to the parent carrier, wild-type parent, and the controls.

Lymphoblastoid cells from affected probands have severe TYMS deficiency, altered cellular deoxyribonucleotide triphosphate pools, and hypersensitivity to the TYMS-specific inhibitor 5-fluorouracil. These defects in the nucleotide metabolism pathway resulted in genotoxic stress, defective transcription, and abnormal telomere maintenance. Gene-rescue studies in cells from affected probands revealed that post-transcriptional epistatic silencing of TYMS is occurring via elevated ENOSF1.
Sources: Literature

Created: 1 Sep 2022, 7:04 a.m.

Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown

Phenotypes
Dyskeratosis congenita MONDO:0015780

Publications

• 35931051