chr4-41746228-T-A

Position:

• chr4-41746228-T-A

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 2P and 1B. PM2 BP4

The NM_003924.4(PHOX2B):​c.524A>T​(p.Lys175Met) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,642 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts 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. K175R) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• 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 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.27196985).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PHOX2B	NM_003924.4	c.524A>T	p.Lys175Met	missense_variant	3/3	ENST00000226382.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PHOX2B	ENST00000226382.4	c.524A>T	p.Lys175Met	missense_variant	3/3	1	NM_003924.4	P1
PHOX2B	ENST00000510424.2	n.345A>T		non_coding_transcript_exon_variant	3/3	3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461642 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727148

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: 0.00000270

Gnomad4 OTH exome AF: 0.00

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 18, 2023

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. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt PHOX2B protein function. ClinVar contains an entry for this variant (Variation ID: 406403). This variant has not been reported in the literature in individuals affected with PHOX2B-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces lysine, which is basic and polar, with methionine, which is neutral and non-polar, at codon 175 of the PHOX2B protein (p.Lys175Met). -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jun 04, 2022

The p.K175M variant (also known as c.524A>T), located in coding exon 3 of the PHOX2B gene, results from an A to T substitution at nucleotide position 524. The lysine at codon 175 is replaced by methionine, an amino acid with similar properties. This amino acid position is conserved. In addition, the in silico prediction for this alteration is inconclusive. 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	Pathogenic	0.71
BayesDel_addAF	Uncertain	0.075	D
BayesDel_noAF	Benign	-0.13
CADD	Uncertain	25
DANN	Benign	0.92
DEOGEN2	Benign	0.38	T
Eigen	Benign	-0.47
Eigen_PC	Benign	-0.53
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Benign	0.73	T
M_CAP	Uncertain	0.20	D
MetaRNN	Benign	0.27	T
MetaSVM	Benign	-0.98	T
MutationAssessor	Benign	1.7	L
MutationTaster	Benign	0.56	N
PrimateAI	Uncertain	0.74	T
PROVEAN	Benign	-2.4	N
REVEL	Uncertain	0.38
Sift	Uncertain	0.0040	D
Sift4G	Uncertain	0.016	D
Polyphen		0.58	P
Vest4		0.36
MutPred		0.29		Loss of solvent accessibility (P = 0.0045);
MVP		0.76
MPC		1.5
ClinPred		0.84	D
GERP RS		0.97
Varity_R		0.28
gMVP		0.73

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;