rs1555212359

Variant names:

• chr12-120997522-GC-G
• rs1555212359
• NM_000545.8:c.1359delC

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PVS1 PM2_Supporting

This summary comes from the ClinGen Evidence Repository: The c.1359del variant in the HNF1 homeobox A gene, HNF1A, causes a frameshift in the protein at codon 454 (NM_000545.8), adding 3 novel amino acids before encountering a stop codon (p.(Ser454AlafsTer3)). This variant, located in biologically-relevant exon 7 of 10, is predicted to lead 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 and v4.1.0 (PM2_Supporting). This variant was identified in an individual with a clinical history suggestive of HNF1A-MODY (MODY probability calculator result >50%); however, HNF4A was not tested (internal lab contributors). In summary, c.1359del meets the criteria to be classified as likely pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP (specification version 3.0.0, approved 6/30/2025): PVS1, PM2_Supporting. LINK:https://erepo.genome.network/evrepo/ui/classification/CA645372549/MONDO:0015967/017

• Frequency: Genomes: not found (cov: 32)
• Consequence: HNF1A NM_000545.8 frameshift
• Clinical Significance: Likely pathogenic reviewed by expert panel P:4
• Conservation: PhyloP100: -0.507
• Publications: 0 publications found

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]

HNF1A Gene-Disease associations (from GenCC):

• monogenic diabetes

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• type 1 diabetes mellitus 20

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Laboratory for Molecular Medicine, Genomics England PanelApp
• diabetes mellitus, noninsulin-dependent

  Inheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp
• maturity-onset diabetes of the young type 3

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp
• hyperinsulinism due to HNF1A deficiency

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• maturity-onset diabetes of the young

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• nonpapillary renal cell carcinoma

  Inheritance: Unknown Classification: NO_KNOWN Submitted by: Labcorp Genetics (formerly Invitae)

ACMG classification

Specifications for HNF1A are available in the ClinGen Criteria Specification Registry and recommended for reference when assigning criteria.

Our verdict: Likely_pathogenic. The variant received 9 ACMG points.

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

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000545.8. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	HNF1A	NM_000545.8	MANE Select	c.1359delC	p.Ser454AlafsTer3	frameshift	Exon 7 of 10	NP_000536.6
	HNF1A	NM_001306179.2		c.1359delC	p.Ser454AlafsTer3	frameshift	Exon 7 of 10	NP_001293108.2	F5H0K0
	HNF1A	NM_001406915.1		c.1309+781delC		intron	N/A	NP_001393844.1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	HNF1A	ENST00000257555.11	TSL:1 MANE Select	c.1359delC	p.Ser454AlafsTer3	frameshift	Exon 7 of 10	ENSP00000257555.5	P20823-1
	HNF1A	ENST00000544413.2	TSL:1	c.1359delC	p.Ser454AlafsTer3	frameshift	Exon 7 of 10	ENSP00000438804.1	F5H0K0
	HNF1A	ENST00000535955.5	TSL:1	n.75delC		non_coding_transcript_exon	Exon 2 of 2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

ClinVar submissions

Significance: Likely pathogenic

Revision: reviewed by expert panel

Pathogenic	VUS	Benign	Condition
1	-	-	Maturity-onset diabetes of the young (1)
1	-	-	Maturity-onset diabetes of the young type 3 (1)
1	-	-	Monogenic diabetes (1)
1	-	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		-0.51
Mutation Taster		=1/199	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs1555212359; hg19: chr12-121435325;