6-24522772-T-G

Variant names:

• chr6-24522772-T-G
• rs887448536
• NM_001080.3:c.1020T>G

Variant summary

Our verdict is Likely pathogenic. The variant received 7 ACMG points: 7P and 0B. PM2 PP2 PP3_Strong

The NM_001080.3(ALDH5A1):​c.1020T>G​(p.Cys340Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,690 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 (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. C340S) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: ALDH5A1 NM_001080.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.580
• Publications: 0 publications found

Genes affected

ALDH5A1 (HGNC:408): (aldehyde dehydrogenase 5 family member A1) This protein belongs to the aldehyde dehydrogenase family of proteins. This gene encodes a mitochondrial NAD(+)-dependent succinic semialdehyde dehydrogenase. A deficiency of this enzyme, known as 4-hydroxybutyricaciduria, is a rare inborn error in the metabolism of the neurotransmitter 4-aminobutyric acid (GABA). In response to the defect, physiologic fluids from patients accumulate GHB, a compound with numerous neuromodulatory properties. Two transcript variants encoding distinct isoforms have been identified for this gene. [provided by RefSeq, Jul 2008]

ALDH5A1 Gene-Disease associations (from GenCC):

• succinic semialdehyde dehydrogenase deficiency

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, ClinGen, Orphanet, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Likely_pathogenic. The variant received 7 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 55 curated pathogenic missense variants (we use a threshold of 10). The gene has 13 curated benign missense variants. Gene score misZ: 0.73405 (below the threshold of 3.09). Trascript score misZ: 0.28023 (below the threshold of 3.09). GenCC associations: The gene is linked to succinic semialdehyde dehydrogenase deficiency.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.983

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001080.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ALDH5A1	NM_001080.3	MANE Select	c.1020T>G	p.Cys340Trp	missense	Exon 7 of 10	NP_001071.1
	ALDH5A1	NM_170740.1		c.1059T>G	p.Cys353Trp	missense	Exon 8 of 11	NP_733936.1
	ALDH5A1	NM_001368954.1		c.876T>G	p.Cys292Trp	missense	Exon 6 of 9	NP_001355883.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ALDH5A1	ENST00000357578.8	TSL:1 MANE Select	c.1020T>G	p.Cys340Trp	missense	Exon 7 of 10	ENSP00000350191.3
	ALDH5A1	ENST00000348925.2	TSL:1	c.1059T>G	p.Cys353Trp	missense	Exon 8 of 11	ENSP00000314649.3
	ALDH5A1	ENST00000491546.5	TSL:5	c.936T>G	p.Cys312Trp	missense	Exon 6 of 9	ENSP00000417687.1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461690 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727160

African (AFR) AF: 0.00 AC: 0 AN: 33474

American (AMR) AF: 0.00 AC: 0 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26128

East Asian (EAS) AF: 0.00 AC: 0 AN: 39682

South Asian (SAS) AF: 0.00 AC: 0 AN: 86246

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53396

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111900

Other (OTH) AF: 0.00 AC: 0 AN: 60378

GnomAD4 genome Cov.: 31

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Succinate-semialdehyde dehydrogenase deficiency Uncertain:1

Dec 02, 2019

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces cysteine with tryptophan at codon 340 of the ALDH5A1 protein (p.Cys340Trp). The cysteine residue is highly conserved and there is a large physicochemical difference between cysteine and tryptophan. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals with ALDH5A1-related disease. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.88
BayesDel_addAF	Pathogenic	0.46	D
BayesDel_noAF	Pathogenic	0.42
CADD	Benign	22
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.90	D
Eigen	Uncertain	0.39
Eigen_PC	Benign	0.10
FATHMM_MKL	Uncertain	0.87	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Pathogenic	0.50	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Pathogenic	0.85	D
MutationAssessor	Pathogenic	4.8	H
PhyloP100		0.58
PrimateAI	Pathogenic	0.81	D
PROVEAN	Pathogenic	-11	D
REVEL	Pathogenic	0.77
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.99
MutPred		0.84		Gain of MoRF binding (P = 0.0126)
MVP		0.98
MPC		1.1
ClinPred		1.0	D
GERP RS		-5.4
Varity_R		0.99
gMVP		0.98
Mutation Taster		=0/100	disease causing

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

Other links and lift over

dbSNP: rs887448536; hg19: chr6-24523000;