1-171092770-G-T

Position:

• chr1-171092770-G-T

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_001002294.3(FMO3):​c.112G>T​(p.Gly38Trp) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: FMO3 NM_001002294.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.52

Genes affected

FMO3 (HGNC:3771): (flavin containing dimethylaniline monoxygenase 3) Flavin-containing monooxygenases (FMO) are an important class of drug-metabolizing enzymes that catalyze the NADPH-dependent oxygenation of various nitrogen-,sulfur-, and phosphorous-containing xenobiotics such as therapeutic drugs, dietary compounds, pesticides, and other foreign compounds. The human FMO gene family is composed of 5 genes and multiple pseudogenes. FMO members have distinct developmental- and tissue-specific expression patterns. The expression of this FMO3 gene, the major FMO expressed in adult liver, can vary up to 20-fold between individuals. This inter-individual variation in FMO3 expression levels is likely to have significant effects on the rate at which xenobiotics are metabolised and, therefore, is of considerable interest to the pharmaceutical industry. This transmembrane protein localizes to the endoplasmic reticulum of many tissues. Alternative splicing of this gene results in multiple transcript variants encoding different isoforms. Mutations in this gene cause the disorder trimethylaminuria (TMAu) which is characterized by the accumulation and excretion of unmetabolized trimethylamine and a distinctive body odor. In healthy individuals, trimethylamine is primarily converted to the non odorous trimethylamine N-oxide.[provided by RefSeq, Jan 2016]

(HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.989

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
FMO3	NM_001002294.3	c.112G>T	p.Gly38Trp	missense_variant	2/9	ENST00000367755.9	NP_001002294.1
FMO3	NM_006894.6	c.112G>T	p.Gly38Trp	missense_variant	2/9		NP_008825.4
FMO3	NM_001319174.2	c.112G>T	p.Gly38Trp	missense_variant	2/8		NP_001306103.1
FMO3	NM_001319173.2	c.-76G>T		5_prime_UTR_variant	2/10		NP_001306102.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
FMO3	ENST00000367755.9	c.112G>T	p.Gly38Trp	missense_variant	2/9	1	NM_001002294.3	ENSP00000356729	P1
	ENST00000669750.1	n.533+75334C>A		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Aug 28, 2024

Variant summary: FMO3 c.112G>T (p.Gly38Trp) results in a non-conservative amino acid change in the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 251392 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.112G>T has been reported in the literature in at least one individual affected with Trimethylaminuria (e.g. Ferreira_2013). This report does not provide unequivocal conclusions about association of the variant with Trimethylaminuria. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. No submitters have cited clinical-significance assessments for this variant to ClinVar. The following publication has been ascertained in the context of this evaluation (PMID: 23791655). Based on the evidence outlined above, the variant was classified as uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.94
BayesDel_addAF	Pathogenic	0.44	D
BayesDel_noAF	Pathogenic	0.40
CADD	Pathogenic	26
DANN	Uncertain	1.0
DEOGEN2	Benign	0.27	T;T
Eigen	Pathogenic	0.68
Eigen_PC	Uncertain	0.50
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.99	D;D
M_CAP	Pathogenic	0.55	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Pathogenic	0.93	D
MutationAssessor	Pathogenic	4.7	H;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Benign	0.48	T
PROVEAN	Pathogenic	-7.5	D;.
REVEL	Pathogenic	0.86
Sift	Pathogenic	0.0	D;.
Sift4G	Pathogenic	0.0	D;D
Polyphen		1.0	D;.
Vest4		0.97
MutPred		0.92		Loss of disorder (P = 0.0573);Loss of disorder (P = 0.0573);
MVP		0.81
MPC		0.32
ClinPred		1.0	D
GERP RS		3.6
Varity_R		0.89
gMVP		0.83

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr1-171061911; COSMIC: COSV100882410;