Bone Marrow Failure
Gene: THRA
Over 10 sequence variants (including truncating nonsense and frameshift as well as missense) have been reported in the literature in association with consistent phenotype of mild hypothyroidism (growth retardation, relatively high birth length and weight, mild-to-moderate mental retardation, mild skeletal dysplasia, delayed dentition and constipation) and specific facial features. Milder outcomes for missense variants and more severe phenotype manifestations for truncating variants have been observed.
Most of the variants are located in the last exon of the THRA isoform 1 (NM_199334.5; a shorter isoform) affecting the C-terminal ligand binding domain with nonsense and frameshift variants predicted to escape nonsense mediated decay. These variants are either de novo or inherited from an affected parent. A few pedigrees are also available with segregation data. Truncating variants appear to have near complete penetrance whereas missense variants may be associated with variable expressivity (Family C - PMID: 27144938).
Note routine TFTs can be normal.
We have identified multiple individuals internally with pathogenic de novo variants in this gene and macrocytic anaemia.
AMBER rating as only one lineage affected. However, the above patients tested through haematology.
Sources: Expert ReviewCreated: 18 Aug 2025, 1:17 a.m.
Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Phenotypes
Hypothyroidism, congenital, nongoitrous, 6, MIM# 614450
Gene: thra has been classified as Amber List (Moderate Evidence).
Gene: thra has been classified as Amber List (Moderate Evidence).
gene: THRA was added gene: THRA was added to Bone Marrow Failure. Sources: Expert Review Mode of inheritance for gene: THRA was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Phenotypes for gene: THRA were set to Hypothyroidism, congenital, nongoitrous, 6, MIM# 614450 Review for gene: THRA was set to AMBER