1-171090963-G-A

Variant summary

Our verdict is Benign. Variant got -8 ACMG points: 0P and 8B. BP4_Strong BS2

The NM_001002294.3(FMO3):c.-25G>A variant causes a 5 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00797 in 152,464 control chromosomes in the GnomAD database, including 14 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: 𝑓 0.0080 (14 hom., cov: 32)
  • Exomes 𝑓: 0.0079 (0 hom.)
• Consequence: FMO3 NM_001002294.3 5_prime_UTR
• Scores: Splicing: ADA: 0.0001675
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.25

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 Benign. Variant got -8 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.65).
• BS2: High Homozygotes in GnomAd at 14 AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
FMO3	NM_001002294.3	c.-25G>A		5_prime_UTR_variant	1/9	ENST00000367755.9
FMO3	NM_001319173.2	c.-195G>A		splice_region_variant, 5_prime_UTR_variant	1/10
FMO3	NM_001319174.2	c.-25G>A		5_prime_UTR_variant	1/8
FMO3	NM_006894.6	c.-8G>A		splice_region_variant, 5_prime_UTR_variant	1/9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
FMO3	ENST00000367755.9	c.-25G>A		5_prime_UTR_variant	1/9	1	NM_001002294.3	P1
	ENST00000669750.1	n.533+77141C>T		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.00798 AC: 1213 AN: 152096 Hom.: 14 Cov.: 32

Gnomad AFR AF: 0.00273

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00681

Gnomad ASJ AF: 0.00461

Gnomad EAS AF: 0.000193

Gnomad SAS AF: 0.00436

Gnomad FIN AF: 0.00575

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0131

Gnomad OTH AF: 0.00431

GnomAD4 exome AF: 0.00794 AC: 2 AN: 252 Hom.: 0 Cov.: 0 AF XY: 0.0106 AC XY: 2 AN XY: 188

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 NFE exome AF: 0.00909

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.00797 AC: 1213 AN: 152212 Hom.: 14 Cov.: 32 AF XY: 0.00693 AC XY: 516 AN XY: 74422

Gnomad4 AFR AF: 0.00272

Gnomad4 AMR AF: 0.00680

Gnomad4 ASJ AF: 0.00461

Gnomad4 EAS AF: 0.000193

Gnomad4 SAS AF: 0.00436

Gnomad4 FIN AF: 0.00575

Gnomad4 NFE AF: 0.0131

Gnomad4 OTH AF: 0.00427

Alfa AF: 0.0108 Hom.: 13

Bravo AF: 0.00791

Asia WGS AF: 0.00260 AC: 9 AN: 3478

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Trimethylaminuria Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 13, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.65
Cadd	Benign	5.7
Dann	Benign	0.50

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.00017
dbscSNV1_RF	Benign	0.052
SpliceAI score (max)		0.70		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.24		Position offset: 1
DS_DL_spliceai		0.70		Position offset: 18

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs11578281; hg19: chr1-171060104;