3-120638490-AC-ACC

Position:

• chr3-120638490-AC-ACC

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000187.4(HGD):​c.970dupG​(p.Val324fs) 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 Likely pathogenic (★★). 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/Likely pathogenic criteria provided, multiple submitters, no conflicts 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]

HGD (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 18 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 [Likely_pathogenic]. Clinvar id is 371566.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
HGD	NM_000187.4	c.970dupG	p.Val324fs	frameshift_variant	12/14	ENST00000283871.10	NP_000178.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
HGD	ENST00000283871.10	c.970dupG	p.Val324fs	frameshift_variant	12/14	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

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: 0.00000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Alkaptonuria Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Oct 21, 2021	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). -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Oct 19, 2016	- -
Pathogenic, no assertion criteria provided	research	Department Of Human Genetics, Institute Of Clinical And Translational Research, Biomedical Research Center, Slovak Academy Of Sciences	-	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

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

LitVar

Other links and lift over

dbSNP: rs34214309; hg19: chr3-120357337;