Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM1PM2PM5PP2PP3_Strong
The NM_001083962.2(TCF4):c.1831C>A(p.Leu611Ile) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. L611P) has been classified as Likely pathogenic.
TCF4 (HGNC:11634): (transcription factor 4) This gene encodes transcription factor 4, a basic helix-loop-helix transcription factor. The encoded protein recognizes an Ephrussi-box ('E-box') binding site ('CANNTG') - a motif first identified in immunoglobulin enhancers. This gene is broadly expressed, and may play an important role in nervous system development. Defects in this gene are a cause of Pitt-Hopkins syndrome. In addition, an intronic CTG repeat normally numbering 10-37 repeat units can expand to >50 repeat units and cause Fuchs endothelial corneal dystrophy. Multiple alternatively spliced transcript variants that encode different proteins have been described. [provided by RefSeq, Jul 2016]
Verdict is Pathogenic. Variant got 11 ACMG points.
PM1
In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 2 uncertain in NM_001083962.2
PM2
Very rare variant in population databases, with high coverage;
PM5
Other missense variant is known to change same aminoacid residue: Variant chr18-55228894-A-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1706281.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
PP2
Missense variant in the TCF4 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 42 curated pathogenic missense variants (we use a threshold of 10). The gene has 70 curated benign missense variants. Gene score misZ: 4.1035 (above the threshold of 3.09). Trascript score misZ: 4.5676 (above the threshold of 3.09). GenCC associations: The gene is linked to intellectual disability, corneal dystrophy, Fuchs endothelial, 3, autosomal dominant non-syndromic intellectual disability, autism spectrum disorder, Fuchs' endothelial dystrophy, Pitt-Hopkins syndrome.
PP3
MetaRNN computational evidence supports a deleterious effect, 0.972
Review Status: criteria provided, single submitter
Collection Method: clinical testing
In summary, this variant is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a TCF4-related disease. This sequence change replaces leucine with isoleucine at codon 611 of the TCF4 protein (p.Leu611Ile). The leucine residue is highly conserved and there is a small physicochemical difference between leucine and isoleucine. -