12-120993519-G-A

Position:

• chr12-120993519-G-A

Variant summary

Our verdict is Pathogenic. Variant got 17 ACMG points: 17P and 0B. PS4_Moderate PP1_Strong PVS1 PP4_Moderate PM2_Supporting

This summary comes from the ClinGen Evidence Repository: The c.527-1G>A variant in the HNF1 homeobox A gene, HNF1A, is predicted to remove a canonical splice acceptor site in intron 2 of NM_000545.8. This variant is predicted to cause skipping of biologically-relevant exon 3 of 10, resulting in a frameshift, leading to nonsense mediated decay in a gene in which loss-of-function is an established disease mechanism (PVS1; PMID:23348805). Also, this variant is absent from gnomAD v2.1.1 (PM2_Supporting). This variant was identified in 5 unrelated individuals with non- autoimmune and non-absolute/near-absolute insulin-deficient diabetes (PS4_Moderate; PMID:10588527, internal lab contributors). Additionally, this variant was identified in at least 2 individuals with a clinical history suggestive of HNF1A-MODY (MODY probability calculator result >50% and negative genetic testing for HNF4A), including one considered highly specific based on sulfonylurea-responsiveness (PP4_Moderate; internal lab contributors). This variant segregated with diabetes, with 7 informative meioses in 2 families with MODY (PP1_Strong; PMID:10588527, internal lab contributors). In summary, c.527-1G>A meets the criteria to be classified as pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP (specification version 1.0, approved 9/30/2021): PVS1, PM2_Supporting, PS4_Moderate, PP4_Moderate, PP1_Strong. LINK:https://erepo.genome.network/evrepo/ui/classification/CA386963414/MONDO:0015967/017

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: HNF1A NM_000545.8 splice_acceptor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic reviewed by expert panel P:7
• Conservation: PhyloP100: 9.44

Genes affected

HNF1A (HGNC:11621): (HNF1 homeobox A) The protein encoded by this gene is a transcription factor required for the expression of several liver-specific genes. The encoded protein functions as a homodimer and binds to the inverted palindrome 5'-GTTAATNATTAAC-3'. Defects in this gene are a cause of maturity onset diabetes of the young type 3 (MODY3) and also can result in the appearance of hepatic adenomas. Alternative splicing results in multiple transcript variants encoding different isoforms. [provided by RefSeq, Apr 2015]

ACMG classification

Verdict is Pathogenic. Variant got 17 ACMG points.

• PVS1: For more information check the summary or visit ClinGen Evidence Repository.
• PS4: For more information check the summary or visit ClinGen Evidence Repository.
• PM2: For more information check the summary or visit ClinGen Evidence Repository.
• PP1: For more information check the summary or visit ClinGen Evidence Repository.
• PP4: For more information check the summary or visit ClinGen Evidence Repository.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
HNF1A	NM_000545.8	c.527-1G>A		splice_acceptor_variant		ENST00000257555.11	NP_000536.6
HNF1A	NM_001306179.2	c.527-1G>A		splice_acceptor_variant			NP_001293108.2
HNF1A	NM_001406915.1	c.527-1G>A		splice_acceptor_variant			NP_001393844.1
HNF1A	XM_024449168.2	c.527-1G>A		splice_acceptor_variant			XP_024304936.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
HNF1A	ENST00000257555.11	c.527-1G>A		splice_acceptor_variant		1	NM_000545.8	ENSP00000257555	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461620 Hom.: 0 Cov.: 34 AF XY: 0.00 AC XY: 0 AN XY: 727108

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:7

Revision: reviewed by expert panel

Submissions by phenotype

not provided Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Athena Diagnostics	Nov 11, 2020	This variant is expected to severely impact normal RNA splicing, and consequently, protein structure and/or function. This variant has not been reported in large, multi-ethnic general populations (http://gnomad.broadinstitute.org). This variant appears to be associated with disease in at least one family, however, the available information does not rule out an apparent association due to chance. Computational tools yielded predictions that this variant may interfere with normal RNA splicing. -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jan 11, 2024	This sequence change affects an acceptor splice site in intron 2 of the HNF1A gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in HNF1A are known to be pathogenic (PMID: 15928245, 18003757). This variant is not present in population databases (gnomAD no frequency). Disruption of this splice site has been observed in individual(s) with HNF1A-related conditions (PMID: 10588527). It has also been observed to segregate with disease in related individuals. This variant is also known as IVS2nt-1G>A. ClinVar contains an entry for this variant (Variation ID: 449035). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Feb 14, 2022	Not observed at significant frequency in large population cohorts (gnomAD); Canonical splice site variant in a gene for which loss-of-function is a known mechanism of disease; This variant is associated with the following publications: (PMID: 25525159, 11315828, 10588527) -

Maturity onset diabetes mellitus in young Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Dec 22, 2023	Variant summary: HNF1A c.527-1G>A is located in a canonical splice-site and is predicted to affect mRNA splicing resulting in a significantly altered protein due to either exon skipping, shortening, or inclusion of intronic material. Several computational tools predict a significant impact on normal splicing: Four predict the variant abolishes a canonical 3' splice acceptor site, and two predict the variant creates a cryptic 3' acceptor site. However, these predictions have yet to be confirmed by functional studies. The variant was absent in 251006 control chromosomes (gnomAD). c.527-1G>A has been reported in the literature in multiple individuals affected with Maturity Onset Diabetes Of The Young 3 with evidence of cosegregation with disease (Ng_1999, Mirshahi_2022). These data indicate that the variant is very likely to be associated with disease. The following publications have been ascertained in the context of this evaluation (PMID: 10588527, 36257325). Five submitters, including a ClinGen expert panel, have cited clinical-significance assessments for this variant to ClinVar after 2014. All submitters classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -
Likely pathogenic, criteria provided, single submitter	research	Clinical Genomics, Uppaluri K&H Personalized Medicine Clinic	-	Mutations in HNF1A gene can predispose to MODY3. It is associated with both micro and macrovascular complications of diabetes, especially cardiovascular complications. Associated with glucosuria. May respond well to sulfonylureas. However, more evidence is required to confer the association of this particular variant rs1555211904 with MODY3. -

Monogenic diabetes Pathogenic:1

Pathogenic, reviewed by expert panel

curation

ClinGen Monogenic Diabetes Variant Curation Expert Panel

Apr 10, 2022

The c.527-1G>A variant in the HNF1 homeobox A gene, HNF1A, is predicted to remove a canonical splice acceptor site in intron 2 of NM_000545.8. This variant is predicted to cause skipping of biologically-relevant exon 3 of 10, resulting in a frameshift, leading to nonsense mediated decay in a gene in which loss-of-function is an established disease mechanism (PVS1; PMID: 23348805). Also, this variant is absent from gnomAD v2.1.1 (PM2_Supporting). This variant was identified in 5 unrelated individuals with non- autoimmune and non-absolute/near-absolute insulin-deficient diabetes (PS4_Moderate; PMID: 10588527, internal lab contributors). Additionally, this variant was identified in at least 2 individuals with a clinical history suggestive of HNF1A-MODY (MODY probability calculator result >50% and negative genetic testing for HNF4A), including one considered highly specific based on sulfonylurea-responsiveness (PP4_Moderate; internal lab contributors). This variant segregated with diabetes, with 7 informative meioses in 2 families with MODY (PP1_Strong; PMID: 10588527, internal lab contributors). In summary, c.527-1G>A meets the criteria to be classified as pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP (specification version 1.0, approved 9/30/2021): PVS1, PM2_Supporting, PS4_Moderate, PP4_Moderate, PP1_Strong. -

Maturity-onset diabetes of the young type 3 Pathogenic:1

Pathogenic, criteria provided, single submitter

research

Geisinger Clinic, Geisinger Health System

Aug 02, 2022

PVS1, PM2, PP3, PP4, PS4_Moderate, PP1_Strong -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.34
CADD	Pathogenic	34
DANN	Uncertain	1.0
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	0.99
FATHMM_MKL	Pathogenic	1.0	D
MutationTaster	Benign	1.0	D;D;D;D;D
GERP RS		5.0

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.95
SpliceAI score (max)		0.94		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.37		Position offset: 3
DS_AL_spliceai		0.94		Position offset: 1

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

Publications

LitVar

Other links and lift over

dbSNP: rs1555211904; hg19: chr12-121431322;