rs786205431

Variant names:

• chr1-23802525-TAA-T
• rs786205431
• NM_000191.3:c.914_915delTT

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1_Moderate PM2 PP5_Very_Strong

The NM_000191.3(HMGCL):​c.914_915delTT​(p.Phe305TyrfsTer10) variant causes a frameshift change. The variant allele was found at a frequency of 0.0000041 in 1,461,758 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. F305F) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: HMGCL NM_000191.3 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:11
• Conservation: PhyloP100: 5.04

Genes affected

HMGCL (HGNC:5005): (3-hydroxy-3-methylglutaryl-CoA lyase) The protein encoded by this gene belongs to the HMG-CoA lyase family. It is a mitochondrial enzyme that catalyzes the final step of leucine degradation and plays a key role in ketone body formation. Mutations in this gene are associated with HMG-CoA lyase deficiency. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Oct 2009]

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. Fraction of 0.0654 CDS is truncated, and there are 1 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 1-23802525-TAA-T is Pathogenic according to our data. Variant chr1-23802525-TAA-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 31084.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr1-23802525-TAA-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
HMGCL	NM_000191.3	c.914_915delTT	p.Phe305TyrfsTer10	frameshift_variant	Exon 9 of 9	ENST00000374490.8	NP_000182.2
HMGCL	NM_001166059.2	c.701_702delTT	p.Phe234TyrfsTer10	frameshift_variant	Exon 7 of 7		NP_001159531.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
HMGCL	ENST00000374490.8	c.914_915delTT	p.Phe305TyrfsTer10	frameshift_variant	Exon 9 of 9	1	NM_000191.3	ENSP00000363614.3
HMGCL	ENST00000436439.6	c.701_702delTT	p.Phe234TyrfsTer10	frameshift_variant	Exon 7 of 7	2		ENSP00000389281.2
HMGCL	ENST00000235958.4	c.482_483delTT	p.Phe161fs	frameshift_variant	Exon 5 of 5	5		ENSP00000235958.4
HMGCL	ENST00000374487.6	n.1511_1512delTT		non_coding_transcript_exon_variant	Exon 10 of 10	2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251490 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135920

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000289

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: 0.00000410 AC: 6 AN: 1461758 Hom.: 0 AF XY: 0.00000413 AC XY: 3 AN XY: 727200

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000113

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:11

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Deficiency of hydroxymethylglutaryl-CoA lyase Pathogenic:10

Feb 03, 2020

Centre for Mendelian Genomics, University Medical Centre Ljubljana

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was classified as: Pathogenic. The following ACMG criteria were applied in classifying this variant: PVS1,PS1,PM2. -

Mar 26, 2024

Genomic Medicine Center of Excellence, King Faisal Specialist Hospital and Research Centre

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Apr 11, 2023

Genome-Nilou Lab

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Mar 04, 2024

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jun 18, 2024

Fulgent Genetics, Fulgent Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Sep 24, 2018

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

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: HMGCL c.914_915delTT (p.Phe305TyrfsX10) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. The variant allele was found at a frequency of 7.2e-06 in 277236 control chromosomes. c.914_915delTT has been reported in the literature in two homozygous individuals affected with HMG-CoA Lyase Deficiency (Mitchell_1998). These data indicate that the variant is likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Two clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation, and both classified the variant as pathogenic/likely pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

Nov 23, 2020

Genetics and Molecular Pathology, SA Pathology

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

PVS1, PM2, PP5, PP4 -

Feb 01, 1998

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Jul 17, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This premature translational stop signal has been observed in individual(s) with HMGCL-related conditions (PMID: 2443756, 6085636, 9463337). This sequence change creates a premature translational stop signal (p.Phe305Tyrfs*10) in the HMGCL gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 21 amino acid(s) of the HMGCL protein. This variant is present in population databases (rs786205431, gnomAD 0.003%). This variant is also known as F305 fs(-2) in literature. ClinVar contains an entry for this variant (Variation ID: 31084). This variant disrupts the C-terminus of the HMGCL protein. Other variant(s) that disrupt this region (p.Gln308*) have been observed in individuals with HMGCL-related conditions (PMID: 11129331). This suggests that this may be a clinically significant region of the protein. For these reasons, this variant has been classified as Pathogenic. -

Jan 16, 2018

Counsyl

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Pathogenic:1

Feb 20, 2015

Eurofins Ntd Llc (ga)

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

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: rs786205431; hg19: chr1-24129015;