Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2PP3
The NM_000352.6(ABCC8):c.4608G>A(p.Ala1536Ala) variant causes a splice region, synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000372 in 1,614,108 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. 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]
Review Status: criteria provided, single submitter
Collection Method: clinical testing
In-silico analysis, which includes splice predictors and evolutionary conservation, is inconclusive as to whether the variant alters gene splicing. In the absence of RNA/functional studies, the actual effect of this sequence change is unknown; Not observed in large population cohorts (Lek et al., 2016); This variant is associated with the following publications: (PMID: 28018462, 33410562) -
Feb 28, 2022
Labcorp Genetics (formerly Invitae), Labcorp
Significance: Uncertain significance
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This sequence change affects codon 1536 of the ABCC8 mRNA. It is a 'silent' change, meaning that it does not change the encoded amino acid sequence of the ABCC8 protein. This variant also falls at the last nucleotide of exon 38, which is part of the consensus splice site for this exon. This variant is not present in population databases (gnomAD no frequency). This variant has been observed in individual(s) with congenital hyperinsulinism (PMID: 28018462, 33410562). This variant is also known as c.4611G>A (p.Ala1537=). ClinVar contains an entry for this variant (Variation ID: 555529). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). 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. -
Type 2 diabetes mellitus Pathogenic:1
Oct 02, 2023
Baylor Genetics
Significance: Likely pathogenic
Review Status: criteria provided, single submitter