Repeat Disorders
STR: BCLAF3_FRAXG_CCG
PMID 42482100 reports five affected males with X‑linked hypermethylated CCG repeat expansions in the 5′UTR of BCLAF3, causing transcriptional silencing (loss‑of‑function). Affected individuals present with intellectual disability, epilepsy and autism. Patient‑derived fibroblasts show loss of BCLAF3 RNA and protein and DNA‑methylation arrays confirm promoter hypermethylation. One of the individuals had Williams syndrome and one of the individuals had fragile X, but more severe phenotypes than expected.
Based on LRS across all the individuals, the suggested threshold for hypermethylation is somewhere between 117-172 CCG repeats, but a greater number of individuals with intermediate-sized expansions are required to define a more precise cutoff.
Sources: LiteratureCreated: 19 Aug 2026, 8:03 p.m.
Mode of inheritance
X-LINKED: hemizygous mutation in males, biallelic mutations in females
Phenotypes
Neurodevelopmental disorder, MONDO:0700092
Publications
STR: BCLAF3_FRAXG_CCG was added STR: BCLAF3_FRAXG_CCG was added to Repeat Disorders. Sources: Expert Review Green,Literature Mode of inheritance for STR: BCLAF3_FRAXG_CCG was set to X-LINKED: hemizygous mutation in males, biallelic mutations in females Publications for STR: BCLAF3_FRAXG_CCG were set to 42482100 Phenotypes for STR: BCLAF3_FRAXG_CCG were set to Neurodevelopmental disorder, MONDO:0700092