Traits

Traits linked to SMPD4

sphingomyelin phosphodiesterase 4

The Human Phenotype Ontology links 43 traits to SMPD4, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of head or neck

Trait	How often it is seen
Progressively abnormally small cranium	Very often (80–99%)
Abnormally small head	Often (30–79%)
Big lower jaw	Sometimes (5–29%)
Both sided cleft lip	Sometimes (5–29%)
Bulbous nose	Sometimes (5–29%)
Decreased volume of lip	Sometimes (5–29%)
Downward slanting of the opening between the eyelids	Sometimes (5–29%)
Eye folds	Sometimes (5–29%)
Highly arched eyebrow	Sometimes (5–29%)
Low frontal hairline	Sometimes (5–29%)
Short opening between the eyelids	Sometimes (5–29%)
Short philtrum	Sometimes (5–29%)
Sloping forehead	Sometimes (5–29%)
Tented mouth	Sometimes (5–29%)
Thin red part of the upper lip	Sometimes (5–29%)
Bifid uvula	Rarely (1–4%)
Deep philtrum	Rarely (1–4%)
Depressed nasal bridge	Rarely (1–4%)
Narrow forehead	Rarely (1–4%)
Short neck	Rarely (1–4%)
Smooth philtrum	Rarely (1–4%)

Abnormality of the nervous system

Trait	How often it is seen
Global developmental delay	Always
CNS hypomyelination	Often (30–79%)
Epilepsy	Often (30–79%)
Simplified gyral pattern	Often (30–79%)
Small cerebellum	Often (30–79%)
Small brainstem	Sometimes (5–29%)

Abnormality of limbs

Trait	How often it is seen
Rocker bottom foot	Sometimes (5–29%)
Inward turned thumb	Rarely (1–4%)
Single transverse palmar crease	Rarely (1–4%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Spasticity and rigidity of muscles	Often (30–79%)
Low muscle tone	Sometimes (5–29%)
Arthrogryposis multiplex congenita	Rarely (1–4%)

Abnormality of the ear

Trait	How often it is seen
Ears rotated toward back of head	Sometimes (5–29%)
Prominent ear	Sometimes (5–29%)

Growth abnormality

Trait	How often it is seen
Birth length less than 3rd percentile	Often (30–79%)
Prenatal growth deficiency	Often (30–79%)

Abnormality of prenatal development or birth

Trait	How often it is seen
Premature birth	Often (30–79%)

Abnormality of the breast

Trait	How often it is seen
Wide-spaced nipples	Rarely (1–4%)

Abnormality of the eye

Trait	How often it is seen
Abnormally close eyes	Rarely (1–4%)

Abnormality of the integument

Trait	How often it is seen
Lumbar hypertrichosis	Rarely (1–4%)

Abnormality of the respiratory system

Trait	How often it is seen
Neonatal respiratory distress	Very often (80–99%)

Laboratory abnormality

Trait	How often it is seen
Diabetes mellitus	Sometimes (5–29%)

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 SMPD4 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