4-41745955-G-C

Variant names:

• chr4-41745955-G-C
• rs745709595
• NM_003924.4:c.797C>G

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_003924.4(PHOX2B):​c.797C>G​(p.Ala266Gly) 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. 13/22 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. A266S) has been classified as Likely benign.

• 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: 2.45
• Publications: 0 publications found

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]

PHOX2B Gene-Disease associations (from GenCC):

• central hypoventilation syndrome, congenital, 1, with or without Hirschsprung disease

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), ClinGen, G2P
• Haddad syndrome

  Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: Orphanet, ClinGen
• neuroblastoma, susceptibility to, 2

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, G2P
• congenital central hypoventilation syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.25928164).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_003924.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	PHOX2B	NM_003924.4	MANE Select	c.797C>G	p.Ala266Gly	missense	Exon 3 of 3	NP_003915.2

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	PHOX2B	ENST00000226382.4	TSL:1 MANE Select	c.797C>G	p.Ala266Gly	missense	Exon 3 of 3	ENSP00000226382.2
	PHOX2B	ENST00000510424.2	TSL:3	n.*78C>G		downstream_gene	N/A

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

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

Sep 20, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. Experimental studies and prediction algorithms are not available or were not evaluated, and the functional significance of this variant is currently unknown. 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 alanine, which is neutral and non-polar, with glycine, which is neutral and non-polar, at codon 266 of the PHOX2B protein (p.Ala266Gly).

Hereditary cancer-predisposing syndrome Uncertain:1

Jun 22, 2025

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.A266G variant (also known as c.797C>G), located in coding exon 3 of the PHOX2B gene, results from a C to G substitution at nucleotide position 797. The alanine at codon 266 is replaced by glycine, an amino acid with similar properties. This amino acid position is conserved. In addition, the in silico prediction for this alteration is inconclusive. Based on the available evidence, the clinical significance of this variant remains unclear.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.060
BayesDel_addAF	Uncertain	0.040	T
BayesDel_noAF	Benign	-0.18
CADD	Benign	23
DANN	Uncertain	0.99
DEOGEN2	Benign	0.18	T
Eigen	Benign	-0.083
Eigen_PC	Benign	0.026
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Benign	0.48	T
M_CAP	Pathogenic	0.48	D
MetaRNN	Benign	0.26	T
MetaSVM	Benign	-0.43	T
MutationAssessor	Benign	0.0	N
PhyloP100		2.5
PrimateAI	Pathogenic	0.92	D
PROVEAN	Benign	-0.25	N
REVEL	Benign	0.26
Sift	Benign	0.037	D
Sift4G	Benign	0.37	T
Polyphen		0.84	P
Vest4		0.32
MutPred		0.22		Gain of relative solvent accessibility (P = 0.0023)
MVP		0.72
MPC		1.1
ClinPred		0.28	T
GERP RS		3.7
Varity_R		0.15
gMVP		0.48
Mutation Taster		=73/27	polymorphism

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

Other links and lift over

dbSNP: rs745709595; hg19: chr4-41747972;