Molecular Characteristics

Biallelic variants in TXNL4A are the only known cause for Burn McKeown syndrome. Most affected individuals carry a 34-base pair (bp) deletion, known as the type 1 Δ34, in the TXNL4A promoter of one allele combined with a loss-of-function variant on the other allele (compound heterozygous). Loss-of-function variants include microdeletions, splice site, nonsense and frameshift variants. Alternatively, some affected individuals have been reported as homozygous for a different 34 bp deletion, known as the type 2 Δ34, in the TXNL4A promoter.
No individuals with two loss of function variants in TXNL4A have been described.
Genetic testing must encompass the non-coding promoter sequence and be designed to detect copy number variation in TXNL4A.