rs887448536

Positions:

• chr6-24522772-T-G

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 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 (★).

• 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

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]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a active_site Nucleophile (size 0) in uniprot entity SSDH_HUMAN
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.983

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
ALDH5A1	NM_001080.3	c.1020T>G	p.Cys340Trp	missense_variant	7/10	ENST00000357578.8	NP_001071.1
ALDH5A1	NM_170740.1	c.1059T>G	p.Cys353Trp	missense_variant	8/11		NP_733936.1
ALDH5A1	NM_001368954.1	c.876T>G	p.Cys292Trp	missense_variant	6/9		NP_001355883.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
ALDH5A1	ENST00000357578.8	c.1020T>G	p.Cys340Trp	missense_variant	7/10	1	NM_001080.3	ENSP00000350191	P1

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

Gnomad4 AFR exome AF: 0.00

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

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

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Dec 02, 2019

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. 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. This variant has not been reported in the literature in individuals with ALDH5A1-related disease. This variant is not present in population databases (ExAC no frequency). 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. -

Computational scores

Source: dbNSFP v4.3

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;D;.
Eigen	Uncertain	0.39
Eigen_PC	Benign	0.10
FATHMM_MKL	Uncertain	0.87	D
LIST_S2	Pathogenic	0.99	D;D;D
M_CAP	Pathogenic	0.50	D
MetaRNN	Pathogenic	0.98	D;D;D
MetaSVM	Pathogenic	0.85	D
MutationAssessor	Pathogenic	4.8	H;.;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Pathogenic	0.81	D
PROVEAN	Pathogenic	-11	D;D;D
REVEL	Pathogenic	0.77
Sift	Pathogenic	0.0	D;D;D
Sift4G	Pathogenic	0.0	D;D;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

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: rs887448536; hg19: chr6-24523000;