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FMO3

Synonyms
FMOII, TMAU, dJ127D3.1
External resources
Summary
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.

Variant Counts

Variant classification counts, according to ACMG guideline on all identified variants among our tested samples, are listed. The variants with over 5% variant frequency in population genome databases ( gnomAD, dbSNP, etc.) are excluded.

Pathogenic
37
Likely pathogenic
24
VUS
1,160
Likely benign
4,964
Benign
11

Patient Phenotypes

Proportions of phenotypes among 61 patients carrying pathogenic or likely pathogenic variants on FMO3 gene are displayed below. The following symptoms were found in patients with a variant in FMO3. However, patients may have been diagnosed with a different variant.

Phenotype class
Patients in 3billion (%)
Abnormality of the nervous system
41%
Abnormality of the eye
18%
Abnormality of head or neck
16.4%
Abnormality of the musculoskeletal system
16.4%
Abnormality of the cardiovascular system
8.2%
Abnormality of the digestive system
8.2%
Abnormality of the ear
6.6%
Abnormality of the integument
6.6%
Growth abnormality
4.9%
Abnormality of blood and blood forming tissues
3.3%
Abnormality of metabolism homeostasis
3.3%
Abnormality of the genitourinary system
3.3%
Neoplasm
3.3%
Abnormality of limbs
1.6%
Abnormality of prenatal development or birth
1.6%
Abnormality of the immune system
1.6%
Abnormality of the respiratory system
1.6%
Constitutional symptom
1.6%
Abnormal cellular phenotype
0%
Abnormality of the breast
0%
Abnormality of the endocrine system
0%
Abnormality of the thoracic cavity
0%
Abnormality of the voice
0%

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