chr1-23804451-G-C

Position:

• chr1-23804451-G-C

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1 PM2 PP3_Strong PP5

The NM_000191.3(HMGCL):​c.825C>G​(p.Asn275Lys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. N275S) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: HMGCL NM_000191.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:2
• Conservation: PhyloP100: 0.679

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]

HMGCL (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 9 ACMG points.

• PM1: In a binding_site (size 0) in uniprot entity HMGCL_HUMAN
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.993
• PP5: Variant 1-23804451-G-C is Pathogenic according to our data. Variant chr1-23804451-G-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 556736.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=2, Likely_pathogenic=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
HMGCL	NM_000191.3	c.825C>G	p.Asn275Lys	missense_variant	8/9	ENST00000374490.8	NP_000182.2
HMGCL	NM_001166059.2	c.612C>G	p.Asn204Lys	missense_variant	6/7		NP_001159531.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
HMGCL	ENST00000374490.8	c.825C>G	p.Asn275Lys	missense_variant	8/9	1	NM_000191.3	ENSP00000363614.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Deficiency of hydroxymethylglutaryl-CoA lyase Pathogenic:1 Uncertain:1

Likely pathogenic, criteria provided, single submitter	clinical testing	Neuberg Centre For Genomic Medicine, NCGM	-	The HMGCL (c.825C>G) (p.Asn275Lys) variant has been reported as one of the double heterozygous (c.109G>T (p.Glu37*) variant in an individual affected with HMG-CoA lyase deficiency (Puisac B et. al., 2013). The p.Asn275Lys variant is novel (not in any individuals) in gnomAD Exomes and 1000 Genomes. It has been submitted to ClinVar with as Variant of Uncertain Significance (VUS) but no details are available for independent assessment. The amino acid Asn at position 275 is changed to a Lys changing protein sequence and it might alter its composition and physico-chemical properties. The variant is predicted to be probably damaging by PolyPhen 2 and deleterious by SIFT. For these reasons, this variant has been classified as Likely Pathogenic. In the absence of another reportable variant the molecular diagnosis is not confirmed. -
Uncertain significance, criteria provided, single submitter	clinical testing	Counsyl	Feb 14, 2018	- -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Oct 23, 2024

Variant summary: HMGCL c.825C>G (p.Asn275Lys) results in a non-conservative amino acid change located in the Pyruvate carboxyltransferase domain (IPR000891) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The frequency data for this variant in gnomAD is considered unreliable, as metrics indicate poor data quality at this position. c.825C>G has been reported in the literature in at-least one individual affected with HMG-CoA Lyase Deficiency (example, Puisac_2013). 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. The following publication has been ascertained in the context of this evaluation (PMID: 23465862). ClinVar contains an entry for this variant (Variation ID: 556736). 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	0.98
BayesDel_addAF	Pathogenic	0.23	D
BayesDel_noAF	Uncertain	0.090
CADD	Benign	23
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.99	D;.
Eigen	Uncertain	0.40
Eigen_PC	Uncertain	0.32
FATHMM_MKL	Uncertain	0.87	D
LIST_S2	Pathogenic	0.99	D;D
M_CAP	Pathogenic	0.80	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Uncertain	0.37	D
MutationAssessor	Pathogenic	4.8	H;.
PrimateAI	Uncertain	0.76	T
PROVEAN	Pathogenic	-5.7	D;D
REVEL	Pathogenic	0.83
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0010	D;D
Polyphen		1.0	D;.
Vest4		0.99
MutPred		0.94		Gain of ubiquitination at N275 (P = 0.0162);.;
MVP		0.99
MPC		0.51
ClinPred		1.0	D
GERP RS		3.3
Varity_R		0.97
gMVP		0.99

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: rs1287973337; hg19: chr1-24130941;