rs886062374

chr7-50529300-G-Achr7-50529300-G-T

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM1 PM2 PM5 PP3_Strong PP5

The NM_001082971.2(DDC):c.478C>T(p.Arg160Trp) variant causes a missense change. The variant allele was found at a frequency of 0.00000248 in 1,614,042 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 Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R160Q) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: DDC NM_001082971.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 4.30

Genes affected

DDC (HGNC:2719): (dopa decarboxylase) The encoded protein catalyzes the decarboxylation of L-3,4-dihydroxyphenylalanine (DOPA) to dopamine, L-5-hydroxytryptophan to serotonin and L-tryptophan to tryptamine. Defects in this gene are the cause of aromatic L-amino-acid decarboxylase deficiency (AADCD). AADCD deficiency is an inborn error in neurotransmitter metabolism that leads to combined serotonin and catecholamine deficiency. Multiple alternatively spliced transcript variants encoding different isoforms have been identified for this gene. [provided by RefSeq, Jun 2011]

ACMG classification

Verdict is Pathogenic. Variant got 11 ACMG points.

• PM1: In a helix (size 21) in uniprot entity DDC_HUMAN there are 4 pathogenic changes around while only 0 benign (100%) in NM_001082971.2
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr7-50529300-G-C is described in Lovd as [Pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.96
• PP5: Variant 7-50529300-G-A is Pathogenic according to our data. Variant chr7-50529300-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 360437.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=1, Likely_pathogenic=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
DDC	NM_001082971.2	c.478C>T	p.Arg160Trp	missense_variant	5/15	ENST00000444124.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
DDC	ENST00000444124.7	c.478C>T	p.Arg160Trp	missense_variant	5/15	1	NM_001082971.2	P1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152206 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

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

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461836 Hom.: 0 Cov.: 34 AF XY: 0.00000138 AC XY: 1 AN XY: 727222

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: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152206 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74356

Gnomad4 AFR AF: 0.0000241

Gnomad4 AMR AF: 0.00

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: 0.00000756

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Deficiency of aromatic-L-amino-acid decarboxylase Pathogenic:1 Uncertain:1

Likely pathogenic, criteria provided, single submitter	clinical testing	Invitae	Jan 31, 2022	In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. This variant disrupts the p.Arg160 amino acid residue in DDC. Other variant(s) that disrupt this residue have been observed in individuals with DDC-related conditions (PMID: 31975548), which suggests that this may be a clinically significant amino acid residue. Experimental studies have shown that this missense change affects DDC function (PMID: 29356298). 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. ClinVar contains an entry for this variant (Variation ID: 360437). This missense change has been observed in individual(s) with aromatic L-amino acid decarboxylase deficiency (PMID: 23430870). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces arginine, which is basic and polar, with tryptophan, which is neutral and slightly polar, at codon 160 of the DDC protein (p.Arg160Trp). -
Uncertain significance, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Apr 28, 2017	The DDC c.478C>T (p.Arg160Trp) variant is a missense variant that has been identified in a compound heterozygote state with a second missense variant in one individual with aromatic L-amino acid decarboxylase deficiency (Barth et al. 2011). The AADC enzymatic activity in the patient was 8% of the mean of the child reference range, confirming AADC enzyme deficiency. Control data are unavailable for the p.Arg160Trp variant, and it is not found in the 1000 Genomes Project, the Exome Sequencing Project, or the Exome Aggregation Consortium despite being located in a region of good sequencing coverage. The variant is thus presumed to be rare. The evidence for this variant is limited. The p.Arg160Trp variant is therefore classified as a variant of unknown significance but suspicious for pathogenicity for aromatic L-amino acid decarboxylase deficiency. This variant was observed by ICSL as part of a predisposition screen in an ostensibly healthy population. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.90
BayesDel_addAF	Pathogenic	0.31	D
BayesDel_noAF	Pathogenic	0.21
Cadd	Pathogenic	28
Dann	Uncertain	1.0
DEOGEN2	Pathogenic	0.86	D;T;.;.;D;.
Eigen	Uncertain	0.52
Eigen_PC	Uncertain	0.37
FATHMM_MKL	Uncertain	0.84	D
M_CAP	Pathogenic	0.29	D
MetaRNN	Pathogenic	0.96	D;D;D;D;D;D
MetaSVM	Uncertain	-0.17	T
MutationAssessor	Pathogenic	4.1	H;.;.;.;H;H
MutationTaster	Benign	1.0	D;D;D;D;D
PrimateAI	Uncertain	0.56	T
PROVEAN	Pathogenic	-6.7	D;.;.;D;D;D
REVEL	Pathogenic	0.65
Sift	Pathogenic	0.0	D;.;.;D;D;D
Sift4G	Pathogenic	0.0	D;D;D;D;D;D
Polyphen		1.0	D;.;.;.;D;.
Vest4		0.99
MutPred		0.77		Gain of catalytic residue at A159 (P = 0.0409);Gain of catalytic residue at A159 (P = 0.0409);.;.;Gain of catalytic residue at A159 (P = 0.0409);Gain of catalytic residue at A159 (P = 0.0409);
MVP		0.86
MPC		1.0
ClinPred		1.0	D
GERP RS		2.1
Varity_R		0.90
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: rs886062374; hg19: chr7-50596998; COSMIC: COSV63565026; COSMIC: COSV63565026;