Traits

Traits linked to SAMHD1

SAM and HD domain containing deoxynucleoside triphosphate triphosphohydrolase 1

The Human Phenotype Ontology links 84 traits to SAMHD1, 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
Global developmental delay	Always
Arrhinencephaly	Very often (80–99%)
Cavity within brain	Very often (80–99%)
IQ less than 20	Very often (80–99%)
Leukodystrophy	Very often (80–99%)
Multifocal cerebral white matter abnormalities	Very often (80–99%)
Abnormal gait	Often (30–79%)
Abnormality of extrapyramidal motor function	Often (30–79%)
Brain degeneration	Often (30–79%)
Chronic CSF lymphocytosis	Often (30–79%)
CSF lymphocytic pleiocytosis	Often (30–79%)
Dystonia	Often (30–79%)
Epilepsy	Often (30–79%)
Irritability	Often (30–79%)
Loss of developmental milestones	Often (30–79%)
Loss of speech	Often (30–79%)
Paralysis or weakness of one side of body	Often (30–79%)
Underdevelopment of part of brain called corpus callosum	Often (30–79%)
Ventriculomegaly	Often (30–79%)
Abnormal pyramidal sign	Sometimes (5–29%)
Demyelinating peripheral neuropathy	Sometimes (5–29%)
Headache	Sometimes (5–29%)
Tremor	Sometimes (5–29%)
Degeneration of the striatum	Rarely (1–4%)
Deep white matter hypodensities	Not recorded
Leukoencephalopathy	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Involuntary muscle stiffness, contraction, or spasm	Very often (80–99%)
Spasticity and rigidity of muscles	Very often (80–99%)
Abnormal deposits of calcium in the brain	Often (30–79%)
Basal ganglia calcification	Often (30–79%)
Extrapyramidal muscular rigidity	Often (30–79%)
Intracerebral periventricular calcifications	Often (30–79%)
Low muscle tone in trunk	Often (30–79%)
Arthritis	Sometimes (5–29%)
Multiple joint contractures	Sometimes (5–29%)
Muscle stiffness	Sometimes (5–29%)
Scoliosis	Sometimes (5–29%)
Spastic paraparesis	Sometimes (5–29%)
Spastic tetraplegia	Sometimes (5–29%)
Enchondroma	Rarely (1–4%)
Loss of fat tissue in localized area	Rarely (1–4%)
Disease of the joints	Not recorded
Flexed joint that cannot be straightened	Not recorded

Abnormality of the cardiovascular system

Trait	How often it is seen
Enlarged liver and spleen	Often (30–79%)
Cutis marmorata	Sometimes (5–29%)
Enlarged heart	Sometimes (5–29%)
Raynaud phenomenon	Sometimes (5–29%)
Bulge in wall of large artery that carries blood away from heart	Rarely (1–4%)
Calcification of the aorta	Rarely (1–4%)
Enlarged and thickened heart muscle	Rarely (1–4%)
Moyamoya phenomenon	Rarely (1–4%)

Abnormality of the eye

Trait	How often it is seen
Abnormality of eye movement	Sometimes (5–29%)
Developmental glaucoma	Sometimes (5–29%)
Drooping upper eyelid	Sometimes (5–29%)
Glaucoma	Sometimes (5–29%)
Involuntary, rapid, rhythmic eye movements	Sometimes (5–29%)

Abnormality of the immune system

Trait	How often it is seen
Chilblains	Always
Increased circulating interferon-gamma concentration	Always
Autoimmunity	Often (30–79%)
Inflammation of fat tissue	Sometimes (5–29%)
Muscle inflammation	Rarely (1–4%)

Abnormality of the integument

Trait	How often it is seen
Papillary dermal edema	Always
Dry skin	Often (30–79%)
Photosensitive skin	Often (30–79%)
Persistent blue color of hands or feet	Sometimes (5–29%)
Scaling skin	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Abnormally small head	Often (30–79%)
Beaked nose	Often (30–79%)
Cleft eyelid	Often (30–79%)
Asymmetry of the posterior head	Sometimes (5–29%)

Laboratory abnormality

Trait	How often it is seen
High liver enzymes	Often (30–79%)
Increased CSF interferon alpha	Often (30–79%)
Unexplained fevers	Often (30–79%)
Diabetes mellitus	Sometimes (5–29%)

Abnormality of blood and blood-forming tissues

Trait	How often it is seen
Neonatal alloimmune thrombocytopenia	Sometimes (5–29%)
Chronic lymphatic leukemia	Rarely (1–4%)
Low platelet count	Not recorded

Abnormality of the digestive system

Trait	How often it is seen
Prolonged yellowing of skin in newborn	Sometimes (5–29%)
Feeding difficulties in infancy	Not recorded

Abnormality of the ear

Trait	How often it is seen
Low-set ears	Sometimes (5–29%)

Abnormality of the endocrine system

Trait	How often it is seen
Underactive thyroid	Sometimes (5–29%)

Abnormality of the genitourinary system

Trait	How often it is seen
Short penis	Sometimes (5–29%)

Abnormality of the voice

Trait	How often it is seen
Hoarse voice	Sometimes (5–29%)

Growth abnormality

Trait	How often it is seen
Short stature	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 SAMHD1 and how often each is seen. Find out more at hpo.jax.org.

One test. A lifetime of answers.

From $449Free shipping · Results in 6–8 weeks

Get my Genome Test