4-41746076-C-T

Position:

• chr4-41746076-C-T

Variant summary

Our verdict is Likely benign. Variant got -6 ACMG points: 0P and 6B. BP4_Moderate BS2

The NM_003924.4(PHOX2B):​c.676G>A​(p.Ala226Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000113 in 1,328,460 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/21 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. A226E) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.000011 (0 hom.)
• Consequence: PHOX2B NM_003924.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 0.0990

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 Likely_benign. Variant got -6 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.11684623).
• BS2: High AC in GnomAdExome4 at 15 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PHOX2B	NM_003924.4	c.676G>A	p.Ala226Thr	missense_variant	3/3	ENST00000226382.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PHOX2B	ENST00000226382.4	c.676G>A	p.Ala226Thr	missense_variant	3/3	1	NM_003924.4	P1
PHOX2B	ENST00000510424.2	n.497G>A		non_coding_transcript_exon_variant	3/3	3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.0000113 AC: 15 AN: 1328460 Hom.: 0 Cov.: 31 AF XY: 0.0000106 AC XY: 7 AN XY: 657996

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000339

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: 0.0000133

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

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

Invitae

Sep 06, 2023

This variant has not been reported in the literature in individuals affected with PHOX2B-related conditions. This sequence change replaces alanine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 226 of the PHOX2B protein (p.Ala226Thr). This variant is not present in population databases (gnomAD no frequency). ClinVar contains an entry for this variant (Variation ID: 826611). 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. 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. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jan 25, 2022

The p.A226T variant (also known as c.676G>A), located in coding exon 3 of the PHOX2B gene, results from a G to A substitution at nucleotide position 676. The alanine at codon 226 is replaced by threonine, an amino acid with similar properties. This amino acid position is not well conserved in available vertebrate species. 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	0.086
BayesDel_addAF	Benign	-0.092	T
BayesDel_noAF	Benign	-0.37
CADD	Benign	11
DANN	Benign	0.85
DEOGEN2	Benign	0.20	T
Eigen	Benign	-1.2
Eigen_PC	Benign	-1.2
FATHMM_MKL	Benign	0.17	N
LIST_S2	Benign	0.49	T
M_CAP	Uncertain	0.19	D
MetaRNN	Benign	0.12	T
MetaSVM	Benign	-0.97	T
MutationAssessor	Benign	0.34	N
MutationTaster	Benign	1.0	N
PrimateAI	Pathogenic	0.87	D
PROVEAN	Benign	-0.070	N
REVEL	Benign	0.14
Sift	Benign	0.092	T
Sift4G	Benign	0.42	T
Polyphen		0.039	B
Vest4		0.19
MutPred		0.29		Gain of glycosylation at A226 (P = 0.0012);
MVP		0.79
MPC		1.1
ClinPred		0.033	T
GERP RS		1.4
Varity_R		0.041
gMVP		0.46

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: rs936469212; hg19: chr4-41748093;