BabyScreen+ newborn screening

Gene: RFX5

Green List (high evidence)

Bare lymphocyte syndrome, type II, complementation group C

9 individuals from 8 unrelated families; multiple mouse models
Homozygous and Compound heterozygous (Nonsense, missense, splice site, single bp del) variants were reported resulting in truncated protein and loss of function.
All individuals presented with recurrent lower respiratory tract infection early in life, low CD4+ cells and/or failure to thrive, chronic diarrhoea, hepatosplenomegaly and low Ig levels.
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Bare lymphocyte syndrome, type II, complementation group E

2 siblings (twins) reported with RPX5 variants and new BLS group E phenotype; multiple functional studies
Identified homozygous missense variant (R149Q) which resulted in altered DNA-binding domain and loss of function.
These histo-identical twin brothers had normal numbers of CD4 + cells and are able to mount both cellular and humoral immune responses. They displayed absence of MHC class II surface expression on B cells and mononuclear cells.

Presentation is typically in infancy.

Treatment: BMT.
Sources: Expert Review

Created: 14 Dec 2022, 7:29 a.m.

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
Bare lymphocyte syndrome, type II, complementation group C MIM# 209920; Bare lymphocyte syndrome, type II, complementation group E MIM# 209920