Traits

Traits linked to FH

fumarate hydratase

The Human Phenotype Ontology links 133 traits to FH, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of the nervous system

Trait	How often it is seen
Agenesis of corpus callosum	Always
Ventriculomegaly	Always
Degeneration of cerebrum	Often (30–79%)
Encephalopathy	Often (30–79%)
Epilepsy	Often (30–79%)
Episodic paroxysmal anxiety	Often (30–79%)
Fewer or absent grooves in brain	Often (30–79%)
Global developmental delay	Often (30–79%)
Lethargy	Often (30–79%)
Recurrent paroxysmal headache	Often (30–79%)
Abnormal cerebral white matter morphology	Sometimes (5–29%)
Abnormal corpus callosum morphology	Sometimes (5–29%)
Bilateral polymicrogyria	Sometimes (5–29%)
Cerebral hypomyelination	Sometimes (5–29%)
Coma	Sometimes (5–29%)
Cranial nerve compression	Sometimes (5–29%)
Delayed myelination	Sometimes (5–29%)
Dystonia	Sometimes (5–29%)
Hypsarrhythmia	Sometimes (5–29%)
Inability to move vocal cords	Sometimes (5–29%)
Infantile spasms	Sometimes (5–29%)
Panic attack	Sometimes (5–29%)
Poor eye contact	Sometimes (5–29%)
Tremor	Sometimes (5–29%)
Abnormal speech pattern	Not recorded
Choroid plexus cyst	Not recorded
IQ less than 20	Not recorded
More grooves in brain	Not recorded
Open operculum	Not recorded
Repeated seizures without recovery between them	Not recorded
Small brainstem	Not recorded

Laboratory abnormality

Trait	How often it is seen
Decreased fumarate hydratase activity	Always
Elevated urine fumaric acid level	Always
Increased urine succinate level	Always
Elevated urinary dopamine	Often (30–79%)
Elevated urinary epinephrine level	Often (30–79%)
Elevated urinary norepinephrine level	Often (30–79%)
High blood calcium levels	Often (30–79%)
High urine protein levels	Often (30–79%)
Metabolic acidosis	Often (30–79%)
Blood in urine	Sometimes (5–29%)
Elevated calcitonin	Sometimes (5–29%)
High blood sugar	Sometimes (5–29%)
Increased urine alpha-ketoglutarate concentration	Sometimes (5–29%)
High blood ammonia levels	Rarely (1–4%)
Increased lactate in body	Rarely (1–4%)
Low blood sugar	Rarely (1–4%)
Abnormal urinary amino-acid findings	Not recorded
High blood bilirubin levels	Not recorded

Abnormality of the cardiovascular system

Trait	How often it is seen
Decrease in blood pressure upon standing up	Often (30–79%)
Fainting spell	Often (30–79%)
High blood pressure	Often (30–79%)
Hypertension associated with pheochromocytoma	Often (30–79%)
Hypertensive retinopathy	Often (30–79%)
Palpitations	Often (30–79%)
Perimembranous ventricular septal defect	Often (30–79%)
Positive regitine blocking test	Often (30–79%)
Sinus tachycardia	Often (30–79%)
Arachnoid hemangiomatosis	Sometimes (5–29%)
Cardiac failure	Sometimes (5–29%)
Disease of the heart muscle	Sometimes (5–29%)
Hypertensive crisis	Sometimes (5–29%)
Inflammation of heart muscle	Sometimes (5–29%)

Abnormality of the digestive system

Trait	How often it is seen
Impaired release of bile from liver	Always
Liver failure	Always
Accumulation of fluid in the abdomen	Often (30–79%)
Feeding difficulties in infancy	Often (30–79%)
Intermittent abdominal pain	Often (30–79%)
Nausea	Often (30–79%)
Necrotizing enterocolitis	Often (30–79%)
Abdominal mass	Sometimes (5–29%)
Barrett esophagus	Sometimes (5–29%)
Constipation	Sometimes (5–29%)
Enlarged liver	Sometimes (5–29%)
Esophageal tumor	Sometimes (5–29%)
Vomiting	Sometimes (5–29%)

Abnormality of head or neck

Trait	How often it is seen
Depressed nasal bridge	Often (30–79%)
Frontal bossing	Often (30–79%)
Yellowing of the whites of the eyes	Often (30–79%)
Abnormally small head	Sometimes (5–29%)
Cleft nostril	Sometimes (5–29%)
Nasal tip, upturned	Sometimes (5–29%)
Retinal capillary hemangioma	Sometimes (5–29%)
Tented mouth	Sometimes (5–29%)
High palate	Not recorded
Relatively large head	Not recorded

Abnormality of the integument

Trait	How often it is seen
Cutaneous leiomyoma	Very often (80–99%)
Multiple cutaneous leiomyomas	Very often (80–99%)
Flushing	Often (30–79%)
Itching	Often (30–79%)
Sporadic excessive sweating	Often (30–79%)
Cutaneous leiomyosarcoma	Sometimes (5–29%)
Paleness	Sometimes (5–29%)
Reduced fat tissue below the skin	Not recorded

Abnormality of the genitourinary system

Trait	How often it is seen
Uterine leiomyoma	Always
Cancer starting in small tubes in kidneys	Often (30–79%)
Glomerular sclerosis	Often (30–79%)
Papillary renal cell carcinoma type 2	Sometimes (5–29%)
Renal failure	Sometimes (5–29%)
Uterine leiomyosarcoma	Sometimes (5–29%)
Vaginal tumor	Sometimes (5–29%)

Abnormality of the eye

Trait	How often it is seen
Wide-set eyes	Often (30–79%)
Cerebral visual impairment	Sometimes (5–29%)
Clouding of the lens of the eye	Sometimes (5–29%)
Optic atrophy	Sometimes (5–29%)
Absent iris	Rarely (1–4%)
Visual impairment	Not recorded

Abnormality of prenatal development or birth

Trait	How often it is seen
High levels of amniotic fluid	Always
Bilateral fetal pyelectasis	Often (30–79%)
Premature birth	Often (30–79%)
Low levels of amniotic fluid	Sometimes (5–29%)

Abnormality of the endocrine system

Trait	How often it is seen
Adrenal pheochromocytoma	Very often (80–99%)
Extraadrenal pheochromocytoma	Very often (80–99%)
Paraganglioma	Very often (80–99%)
Paraganglioma of head and neck	Often (30–79%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Muscular abnormality	Very often (80–99%)
Low muscle tone	Often (30–79%)
Poor head control	Sometimes (5–29%)
Generalized decreased muscle tone	Not recorded

Growth abnormality

Trait	How often it is seen
Faltering weight in infancy	Often (30–79%)
Weight loss	Often (30–79%)
Prenatal growth deficiency	Sometimes (5–29%)
Faltering weight	Not recorded

Abnormality of blood and blood-forming tissues

Trait	How often it is seen
Bleeding in brain	Often (30–79%)
Increased red blood cells	Sometimes (5–29%)
Low blood neutrophil count	Sometimes (5–29%)

Abnormality of the ear

Trait	How often it is seen
Paroxysmal vertigo	Often (30–79%)
Pulsatile tinnitus	Often (30–79%)
Conductive deafness	Sometimes (5–29%)

Constitutional symptom

Trait	How often it is seen
Chest pain	Often (30–79%)
Fatigue	Often (30–79%)

Abnormal cellular phenotype

Trait	How often it is seen
Mitochondrial swelling	Always

Abnormality of the voice

Trait	How often it is seen
Inability to produce voice sounds	Often (30–79%)

How often is among people with one of the gene's conditions, the most often across them, as the Human Phenotype Ontology records it. These pages describe traits and the research behind them; they are not a diagnosis, and a doctor or genetic counsellor is the person to ask about symptoms.

Where this comes from

The Human Phenotype Ontology, release 2026-09-01: the traits linked to FH and how often each is seen. Find out more at hpo.jax.org.

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