Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM1PM2PP3_ModeratePP5
The NM_000352.6(ABCC8):c.3763G>A(p.Gly1255Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,454 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).
ABCC8 (HGNC:59): (ATP binding cassette subfamily C member 8) The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the MRP subfamily which is involved in multi-drug resistance. This protein functions as a modulator of ATP-sensitive potassium channels and insulin release. Mutations in the ABCC8 gene and deficiencies in the encoded protein have been observed in patients with hyperinsulinemic hypoglycemia of infancy, an autosomal recessive disorder of unregulated and high insulin secretion. Mutations have also been associated with non-insulin-dependent diabetes mellitus type II, an autosomal dominant disease of defective insulin secretion. Alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Jul 2020]
Verdict is Likely_pathogenic. Variant got 7 ACMG points.
PM1
In a domain ABC transmembrane type-1 2 (size 294) in uniprot entity ABCC8_HUMAN there are 22 pathogenic changes around while only 2 benign (92%) in NM_000352.6
PM2
Very rare variant in population databases, with high coverage;
PP3
MetaRNN computational evidence supports a deleterious effect, 0.903
PP5
Variant 11-17397788-C-T is Pathogenic according to our data. Variant chr11-17397788-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 552431.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=2, Pathogenic=1}.
Review Status: criteria provided, single submitter
Collection Method: clinical testing
Not observed in large population cohorts (Lek et al., 2016); In silico analysis, which includes protein predictors and evolutionary conservation, supports a deleterious effect; Identified with a second variant in trans in a patient with neonatal diabetes mellitus in published literature (Jain et al., 2012); This variant is associated with the following publications: (PMID: 28791793, 28667717, 22796691, 32792356) -
Feb 16, 2024
Labcorp Genetics (formerly Invitae), Labcorp
Significance: Pathogenic
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This sequence change replaces glycine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 1255 of the ABCC8 protein (p.Gly1255Ser). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with ABCC8-related conditions and/or neonatal diabetes mellitus (PMID: 22796691, 28791793, 32792356). In at least one individual the variant was observed to be de novo. This variant is also known as c.3766G>A (p.Gly1256Ser). ClinVar contains an entry for this variant (Variation ID: 552431). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt ABCC8 protein function with a positive predictive value of 80%. For these reasons, this variant has been classified as Pathogenic. -
Type 2 diabetes mellitus Pathogenic:1
Mar 24, 2023
Baylor Genetics
Significance: Likely pathogenic
Review Status: criteria provided, single submitter