Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM1PM2PP3_StrongPP5_Moderate
The NM_000352.6(ABCC8):c.4478G>T(p.Arg1493Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,720 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★).
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 Pathogenic. Variant got 10 ACMG points.
PM1
In a domain ABC transporter 2 (size 234) in uniprot entity ABCC8_HUMAN there are 33 pathogenic changes around while only 3 benign (92%) in NM_000352.6
PM2
Very rare variant in population databases, with high coverage;
PP3
MetaRNN computational evidence supports a deleterious effect, 0.988
PP5
Variant 11-17394333-C-A is Pathogenic according to our data. Variant chr11-17394333-C-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1475961.Status of the report is criteria_provided_single_submitter, 1 stars.
Likely pathogenic, criteria provided, single submitter
clinical testing
Labcorp Genetics (formerly Invitae), Labcorp
Mar 13, 2024
This sequence change replaces arginine, which is basic and polar, with leucine, which is neutral and non-polar, at codon 1493 of the ABCC8 protein (p.Arg1493Leu). This variant is present in population databases (rs746480424, gnomAD 0.002%). This variant has not been reported in the literature in individuals affected with ABCC8-related conditions. ClinVar contains an entry for this variant (Variation ID: 1475961). 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 95%. This variant disrupts the p.Arg1493 amino acid residue in ABCC8. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 9769320, 15579781, 30186238; Invitae). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -