rs764148793

chr21-36754349-C-G

Variant summary

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

The NM_001352514.2(HLCS):c.2519G>C(p.Gly840Ala) variant causes a missense change. The variant allele was found at a frequency of 0.00000248 in 1,613,784 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 (★★).

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: HLCS NM_001352514.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 7.10

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, 0.993

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
HLCS	NM_001352514.2	c.2519G>C	p.Gly840Ala	missense_variant	11/11	ENST00000674895.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
HLCS	ENST00000674895.3	c.2519G>C	p.Gly840Ala	missense_variant	11/11		NM_001352514.2	P4

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152106 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000655

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: 0.00

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.00000798 AC: 2 AN: 250760 Hom.: 0 AF XY: 0.0000148 AC XY: 2 AN XY: 135566

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000579

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: 0.00000205 AC: 3 AN: 1461678 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727120

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000671

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 AF: 0.00000657 AC: 1 AN: 152106 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74298

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.0000655

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000378

ExAC AF: 0.0000247 AC: 3

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

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

Sep 17, 2021

Variant summary: HLCS c.2078G>C (p.Gly693Ala) results in a non-conservative amino acid change located in the Biotin protein ligase, C-terminal (IPR003142) 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 8e-06 in 250760 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.2078G>C has been reported in the literature as a compound heterozygous genotype in at-least one individual affected with Holocarboxylase Synthetase Deficiency (example, Donti_2016) and has been subsequently cited by others (example, Watabe_2018, Zheng_2020). These data do not allow any conclusion about variant significance. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. One clinical diagnostic laboratory has submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation and classified the variant as uncertain significance citing an overlapping evidence utilized in the context of this evaluation. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Holocarboxylase synthetase deficiency Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Counsyl

Aug 08, 2017

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.83
BayesDel_addAF	Pathogenic	0.43	D
BayesDel_noAF	Pathogenic	0.57
Cadd	Uncertain	25
Dann	Uncertain	1.0
DEOGEN2	Pathogenic	0.84	D;D;D
Eigen	Pathogenic	0.90
Eigen_PC	Pathogenic	0.81
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Uncertain	0.91	D;.;.
M_CAP	Pathogenic	0.56	D
MetaRNN	Pathogenic	0.99	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.6	H;H;H
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.58	T
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	D;D;D
Vest4		0.97
MutPred		0.92		Loss of loop (P = 0.1242);Loss of loop (P = 0.1242);Loss of loop (P = 0.1242);
MVP		0.98
MPC		0.60
ClinPred		0.96	D
GERP RS		6.2
Varity_R		0.93
gMVP		0.88

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: rs764148793; hg19: chr21-38126650;