rs1554913069

Positions:

• chr11-17407435-TTCTC-T

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PVS1 PM2 PP5

The NM_000352.6(ABCC8):​c.2835_2838delGAGA​(p.Arg946fs) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,888 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: ABCC8 NM_000352.6 frameshift
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:5 O:2
• Conservation: PhyloP100: 2.22

Genes affected

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]

ABCC8 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 11 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 11-17407435-TTCTC-T is Pathogenic according to our data. Variant chr11-17407435-TTCTC-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 556981.We mark this variant Likely_pathogenic, oryginal submissions are: {Pathogenic=3, Likely_pathogenic=1, Uncertain_risk_allele=2}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
ABCC8	NM_000352.6	c.2835_2838delGAGA	p.Arg946fs	frameshift_variant	24/39	ENST00000389817.8	NP_000343.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
ABCC8	ENST00000389817.8	c.2835_2838delGAGA	p.Arg946fs	frameshift_variant	24/39	1	NM_000352.6	ENSP00000374467.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461888 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 727246

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:5 Other:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Dec 13, 2022	Reported in association with congenital hyperinsulinism (Stanley et al., 2004; Martinez et al., 2016); Frameshift variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 23275527, 14715863, 27188453) -
Likely pathogenic, no assertion criteria provided	clinical testing	Genetic Services Laboratory, University of Chicago	Oct 16, 2022	DNA sequence analysis of the ABCC8 gene demonstrated two sequence changes. The first sequence change is a four base pair deletion in exon 24, c.2835_2838del. This likely pathogenic sequence change results in an amino acid frameshift and creates a premature stop codon 95 amino acids downstream of the change , p.Arg946Lysfs*95. This likely pathogenic sequence change is predicted to result in an abnormal transcript, which may be degraded, or may lead to the production of a truncated ABCC8 protein with potentially abnormal function. The c.2835_2838del sequence change has not been described in population databases such as ExAC and gnomAD. This sequence change has been reported in congenital hyperinsulinism (PMID: 14715863). This sequence change is the likely cause of this individual's phenotype, however functional studies have not been performed to prove this conclusively. -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Sep 08, 2023	This sequence change creates a premature translational stop signal (p.Arg946Lysfs*95) in the ABCC8 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in ABCC8 are known to be pathogenic (PMID: 20685672, 23345197). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with congenital hyperinsulinism (PMID: 14715863, 23275527). ClinVar contains an entry for this variant (Variation ID: 556981). For these reasons, this variant has been classified as Pathogenic. -

Hyperinsulinemic hypoglycemia, familial, 1 Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Nov 29, 2019	Variant summary: ABCC8 c.2835_2838delGAGA (p.Arg946LysfsX95) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Truncations downstream of this position have been classified as pathogenic by our laboratory (c.2992C>T (p.Arg998X), c.3574delG (p.Asp1192fsX16)). The variant was absent in 251486 control chromosomes (gnomAD). c.2835_2838delGAGA has been reported in the literature in individuals affected with Congenital Hyperinsulinism (CH)(Martinez_2016, Snider_2013). These data indicate that the variant is likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. A ClinVar submission (evaluation after 2014) cites the variant as likely pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Mar 01, 2018	- -

Neonatal diabetes mellitus Other:1

Uncertain risk allele, criteria provided, single submitter

research

Clinical Genomics, Uppaluri K&H Personalized Medicine Clinic

May 27, 2024

This variant is found to be a potent moderate impact, variant with a CADD score of 22.8 and sufficient scientific evidence of gene-disease correlation. However, since this is not a high impact variant and no variant evidence, this variant is reclassified as Uncertain risk allele. -

Maturity onset diabetes mellitus in young Other:1

Uncertain risk allele, criteria provided, single submitter

research

Clinical Genomics, Uppaluri K&H Personalized Medicine Clinic

May 27, 2024

This variant is found to be a potent moderate impact variant with a CADD score of 22.8 and sufficient scientific evidence to support gene-disease correlation. However, since this is not a high impact variant and has no variant evidence, this variant is reclassified as Uncertain Risk Allele -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.18		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1554913069; hg19: chr11-17428982;