Our verdict is Likely benign. Variant got -6 ACMG points: 0P and 6B. BP4_ModerateBS2
The NM_001371623.1(TCOF1):c.109-8C>G variant causes a splice region, splice polypyrimidine tract, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000719 in 1,614,054 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★).
TCOF1 (HGNC:11654): (treacle ribosome biogenesis factor 1) This gene encodes a nucleolar protein with a LIS1 homology domain. The protein is involved in ribosomal DNA gene transcription through its interaction with upstream binding factor (UBF). Mutations in this gene have been associated with Treacher Collins syndrome, a disorder which includes abnormal craniofacial development. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Sep 2008]
Uncertain significance, criteria provided, single submitter
clinical testing
Labcorp Genetics (formerly Invitae), Labcorp
Oct 05, 2023
This sequence change falls in intron 1 of the TCOF1 gene. It does not directly change the encoded amino acid sequence of the TCOF1 protein. This variant is present in population databases (rs768938359, gnomAD 0.004%). This variant has not been reported in the literature in individuals affected with TCOF1-related conditions. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -