4-41746228-T-C

Position:

• chr4-41746228-T-C

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_003924.4(PHOX2B):​c.524A>G​(p.Lys175Arg) 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 benign outcome for this variant. 13/21 in silico tools predict a benign 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. K175M) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: PHOX2B NM_003924.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 2.60

Genes affected

PHOX2B (HGNC:9143): (paired like homeobox 2B) The DNA-associated protein encoded by this gene is a member of the paired family of homeobox proteins localized to the nucleus. The protein functions as a transcription factor involved in the development of several major noradrenergic neuron populations and the determination of neurotransmitter phenotype. The gene product is linked to enhancement of second messenger-mediated activation of the dopamine beta-hydroylase, c-fos promoters and several enhancers, including cyclic amp-response element and serum-response element. Expansion of a 20 amino acid polyalanine tract in this protein by 5-13 aa has been associated with congenital central hypoventilation syndrome. [provided by RefSeq, Jul 2016]

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.12865645).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PHOX2B	NM_003924.4	c.524A>G	p.Lys175Arg	missense_variant	3/3	ENST00000226382.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PHOX2B	ENST00000226382.4	c.524A>G	p.Lys175Arg	missense_variant	3/3	1	NM_003924.4	P1
PHOX2B	ENST00000510424.2	n.345A>G		non_coding_transcript_exon_variant	3/3	3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Haddad syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jul 03, 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 are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Not Available"; Align-GVGD: "Class C25"). This variant has not been reported in the literature in individuals with PHOX2B-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces lysine with arginine at codon 175 of the PHOX2B protein (p.Lys175Arg). The lysine residue is highly conserved and there is a small physicochemical difference between lysine and arginine. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

May 21, 2022

The p.K175R variant (also known as c.524A>G), located in coding exon 3 of the PHOX2B gene, results from an A to G substitution at nucleotide position 524. The lysine at codon 175 is replaced by arginine, an amino acid with highly similar properties. This amino acid position is conserved. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.12
BayesDel_addAF	Benign	-0.030	T
BayesDel_noAF	Benign	-0.28
CADD	Uncertain	24
DANN	Benign	0.88
DEOGEN2	Benign	0.30	T
Eigen	Benign	-0.47
Eigen_PC	Benign	-0.53
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Benign	0.66	T
M_CAP	Benign	0.068	D
MetaRNN	Benign	0.13	T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	1.7	L
MutationTaster	Benign	0.95	N
PrimateAI	Uncertain	0.73	T
PROVEAN	Benign	-1.3	N
REVEL	Uncertain	0.29
Sift	Benign	0.034	D
Sift4G	Benign	0.079	T
Polyphen		0.0010	B
Vest4		0.056
MutPred		0.27		Loss of ubiquitination at K175 (P = 0.0077);
MVP		0.79
MPC		0.94
ClinPred		0.38	T
GERP RS		0.97
Varity_R		0.12
gMVP		0.59

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: rs1060501119; hg19: chr4-41748245;