chr12-120978551-T-C

Position:

• chr12-120978551-T-C

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 0P and 2B. BP4_Moderate

The NM_000545.8(HNF1A):​c.-218T>C variant causes a 5 prime UTR change. The variant allele was found at a frequency of 0.0000114 in 615,748 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★★).

• Frequency:
  • Genomes: 𝑓 0.000020 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000086 (0 hom.)
• Consequence: HNF1A NM_000545.8 5_prime_UTR
• Clinical Significance: Uncertain significance reviewed by expert panel U:2
• Conservation: PhyloP100: 4.05

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-AS1 (HGNC:26785): (HNF1A antisense RNA 1)

ACMG classification

Verdict is Likely_benign. Variant got -2 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.29).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
HNF1A	NM_000545.8	c.-218T>C		5_prime_UTR_variant	1/10	ENST00000257555.11
HNF1A	NM_001306179.2	c.-218T>C		5_prime_UTR_variant	1/10
HNF1A	NM_001406915.1	c.-218T>C		5_prime_UTR_variant	1/9
HNF1A	XM_024449168.2	c.-218T>C		5_prime_UTR_variant	1/9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
HNF1A	ENST00000257555.11	c.-218T>C		5_prime_UTR_variant	1/10	1	NM_000545.8	P4
HNF1A-AS1	ENST00000619441.1	n.128+2093A>G		intron_variant, non_coding_transcript_variant		3

Frequencies

GnomAD3 genomes AF: 0.0000198 AC: 3 AN: 151774 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000441

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000862 AC: 4 AN: 463974 Hom.: 0 Cov.: 3 AF XY: 0.0000121 AC XY: 3 AN XY: 247354

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: 0.0000144

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000198 AC: 3 AN: 151774 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74102

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000441

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000113

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: reviewed by expert panel

Submissions by phenotype

Monogenic diabetes Uncertain:1

Uncertain significance, reviewed by expert panel

curation

ClinGen Monogenic Diabetes Variant Curation Expert Panel

Aug 11, 2021

The c.-218T>C variant in the HNF1 homeobox 1 gene, HNF1A gene, is a single nucleotide variant within the promoter region of NM_000545.8. This variant is located within the overlapping HNF3 and NF-Y sites (c.-209 to c.-227) of HNF1A, which is defined as critical for the protein’s function by the ClinGen MDEP (PM1_Supporting). This variant was identified in five unrelated individuals with non- autoimmune and non-absolute/near-absolute insulin-deficient diabetes (internal lab contributors); however, PS4 cannot be applied because the frequency of the c.-218T>C variant is 0.0000319 in gnomAD v2.1.1, which falls between ClinGen MDEP-established cutoffs for PM2_Supporting and BS1; thus, neither PM2_Supporting, BS1, nor PS4_moderate can be applied. Additionally, functional studies demonstrated the variant has transactivation activity at 70% of wildtype, suggesting that this variant does not impact protein function, however sufficient controls were not used per MDEP guidelines and therefore BS3 cannot be applied (PMID: 10649494). Taken together, this evidence supports the classification of this variant as a variant of uncertain significance. ACMP/AMP criteria applied, as specified by the ClinGen MDEP VCEP: PM1_Supporting (specification version 1.0). -

HNF1A-related disorder Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

PreventionGenetics, part of Exact Sciences

Dec 11, 2023

The HNF1A c.-218T>C variant is located in the 5' untranslated region. This variant was previously reported in one individual with maturity onset diabetes of the young (MODY) (Godart et al. 2000. PubMed ID: 10649494). An in vitro assay found that the c.-218T>C variant had a roughly 30% reduction in transcriptional activity compared to a wild-type construct (Godart et al 2000. PubMed ID: 10649494). However, no family studies were performed to help assess the pathogenicity of this variant. This variant is reported in 0.0065% of alleles in individuals of European (Non-Finnish) descent in gnomAD. At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.29
CADD	Benign	20
DANN	Benign	0.91

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		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: rs1024131753; hg19: chr12-121416354;