rs148709879

chr21-36759812-G-Cchr21-36759812-G-A

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_001352514.2(HLCS):c.2151C>G(p.Asn717Lys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,460,596 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Synonymous variant affecting the same amino acid position (i.e. N717N) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: HLCS NM_001352514.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.556

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 Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.992

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
HLCS	NM_001352514.2	c.2151C>G	p.Asn717Lys	missense_variant	9/11	ENST00000674895.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
HLCS	ENST00000674895.3	c.2151C>G	p.Asn717Lys	missense_variant	9/11		NM_001352514.2	P4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251488 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135920

Gnomad AFR exome AF: 0.0000615

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

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: 0.00000274 AC: 4 AN: 1460596 Hom.: 0 Cov.: 29 AF XY: 0.00000138 AC XY: 1 AN XY: 726714

Gnomad4 AFR exome AF: 0.000120

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Bravo AF: 0.0000416

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Nov 16, 2022

Variant summary: HLCS c.1710C>G (p.Asn570Lys) results in a non-conservative amino acid change located in the catalytic domain (IPR004143) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 4e-06 in 251488 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.1710C>G has been reported in the literature in the compound heterozygous state together with a pathogenic variant in an individual affected with Holocarboxylase Synthetase Deficiency (Donti_2016). These data do not allow any strong conclusion about variant significance. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Uncertain	0.13	D
BayesDel_noAF	Uncertain	0.12
Cadd	Benign	22
Dann	Uncertain	1.0
DEOGEN2	Pathogenic	0.95	D;D;D
Eigen	Uncertain	0.47
Eigen_PC	Uncertain	0.24
FATHMM_MKL	Benign	0.68	D
LIST_S2	Uncertain	0.89	D;.;.
M_CAP	Pathogenic	0.81	D
MetaRNN	Pathogenic	0.99	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	5.0	H;H;H
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.70	T
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	D;D;D
Vest4		0.99
MutPred		0.92		Gain of methylation at N570 (P = 0.0171);Gain of methylation at N570 (P = 0.0171);Gain of methylation at N570 (P = 0.0171);
MVP		0.95
MPC		0.62
ClinPred		1.0	D
GERP RS		-2.8
Varity_R		0.98
gMVP		0.98

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.040		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: rs148709879; hg19: chr21-38132113;