chr3-120638490-A-AC

Variant names:

• chr3-120638490-A-AC
• rs34214309
• NM_000187.4:c.970dupG

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_000187.4(HGD):​c.970dupG​(p.Val324GlyfsTer3) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,772 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★). Synonymous variant affecting the same amino acid position (i.e. V324V) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: HGD NM_000187.4 frameshift
• Clinical Significance: Pathogenic criteria provided, single submitter P:3
• Conservation: PhyloP100: 7.36

Genes affected

HGD (HGNC:4892): (homogentisate 1,2-dioxygenase) This gene encodes the enzyme homogentisate 1,2 dioxygenase. This enzyme is involved in the catabolism of the amino acids tyrosine and phenylalanine. Mutations in this gene are the cause of the autosomal recessive metabolism disorder alkaptonuria.[provided by RefSeq, May 2010]

ACMG classification

Our verdict: Pathogenic. The variant received 12 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 3-120638490-A-AC is Pathogenic according to our data. Variant chr3-120638490-A-AC is described in ClinVar as [Pathogenic]. Clinvar id is 371566.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
HGD	NM_000187.4	c.970dupG	p.Val324GlyfsTer3	frameshift_variant	Exon 12 of 14	ENST00000283871.10	NP_000178.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
HGD	ENST00000283871.10	c.970dupG	p.Val324GlyfsTer3	frameshift_variant	Exon 12 of 14	1	NM_000187.4	ENSP00000283871.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461772 Hom.: 0 Cov.: 32 AF XY: 0.00000275 AC XY: 2 AN XY: 727198

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26134

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53410

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000270 AC: 3 AN: 1111914

Other (OTH) AF: 0.00 AC: 0 AN: 60390

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, single submitter

Submissions by phenotype

Alkaptonuria Pathogenic:3

Oct 19, 2016

Counsyl

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -

Oct 21, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 371566). This premature translational stop signal has been observed in individual(s) with alkaptonuria (PMID: 25804398). This variant is not present in population databases (ExAC no frequency). This sequence change creates a premature translational stop signal (p.Val324Glyfs*3) in the HGD gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in HGD are known to be pathogenic (PMID: 12501223, 19862842). -

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Department Of Human Genetics, Institute Of Clinical And Translational Research, Biomedical Research Center, Slovak Academy Of Sciences

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: research

The variant was originally described in AKU patient in PMID:19862842. It has been submitted to the HGD gene mutation database (http://hgddatabase.cvtisr.sk/, DB-ID: AKU_00139). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		7.4
Mutation Taster		=0/200	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.42		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.42		Position offset: -35

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

Publications

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Other links and lift over

dbSNP: rs34214309; hg19: chr3-120357337; COSMIC: COSV99381439;