rs773102942

chr21-36936789-A-AT

Variant summary

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

The NM_001352514.2(HLCS):c.1096_1097insA(p.Ile366AsnfsTer58) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,876 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: HLCS NM_001352514.2 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 0.00300

Genes affected

HLCS (HGNC:4976): (holocarboxylase synthetase) This gene encodes an enzyme that catalyzes the binding of biotin to carboxylases and histones. The protein plays an important role in gluconeogenesis, fatty acid synthesis and branched chain amino acid catabolism. Defects in this gene are the cause of holocarboxylase synthetase deficiency. Multiple alternatively spliced variants, encoding the same protein, have been identified.[provided by RefSeq, Jun 2011]

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 21-36936789-A-AT is Pathogenic according to our data. Variant chr21-36936789-A-AT is described in ClinVar as [Pathogenic]. Clinvar id is 1913.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
HLCS	NM_001352514.2	c.1096_1097insA	p.Ile366AsnfsTer58	frameshift_variant	4/11	ENST00000674895.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
HLCS	ENST00000674895.3	c.1096_1097insA	p.Ile366AsnfsTer58	frameshift_variant	4/11		NM_001352514.2	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.0000119 AC: 3 AN: 251288 Hom.: 0 AF XY: 0.0000147 AC XY: 2 AN XY: 135846

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000163

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461876 Hom.: 0 Cov.: 34 AF XY: 0.00000138 AC XY: 1 AN XY: 727240

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000756

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Holocarboxylase synthetase deficiency Pathogenic:3

Pathogenic, no assertion criteria provided	literature only	OMIM	Nov 01, 2001	- -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Aug 26, 2021	This sequence change creates a premature translational stop signal (p.Ile219Asnfs*58) in the HLCS gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in HLCS are known to be pathogenic (PMID: 16134170). This variant is present in population databases (rs773102942, ExAC 0.03%). This premature translational stop signal has been observed in individuals with holocarboxylase synthetase deficiency (PMID: 11735028). This variant is also known as 655–656insA. ClinVar contains an entry for this variant (Variation ID: 1913). For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Mar 30, 2023	- -

Computational scores

Source: dbNSFP v4.3

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: rs773102942; hg19: chr21-38309089;