Traits

Traits linked to PTDSS1

phosphatidylserine synthase 1

The Human Phenotype Ontology links 100 traits to PTDSS1, 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
Big lower jaw	Always
Broad forehead	Always
Delayed cranial suture closure	Always
Prominent forehead	Always
Thin dental enamel	Always
Abnormal tooth enamel	Very often (80–99%)
Big calvaria	Very often (80–99%)
Blockage of the rear opening of the nasal cavity	Very often (80–99%)
Enlargement of facial bones	Very often (80–99%)
Enlargement of skull bones	Very often (80–99%)
Increased thickness of skull cap	Very often (80–99%)
Wide fontanelles	Very often (80–99%)
Abnormal nasolacrimal system morphology	Often (30–79%)
Abnormally small head	Often (30–79%)
Bell's palsy	Often (30–79%)
Full lips	Often (30–79%)
Narrowing of the tear duct	Often (30–79%)
Wide mouth	Often (30–79%)
Bifid uvula	Sometimes (5–29%)
Cleft palate	Sometimes (5–29%)
High, narrow palate	Sometimes (5–29%)
Submucous cleft hard palate	Sometimes (5–29%)
Abnormal dentition	Not recorded
Abnormally small tongue	Not recorded
Frontal bossing	Not recorded
Little lower jaw	Not recorded
Narrowing of the rear opening of the nasal cavity	Not recorded
Progressive sclerosis of skull base	Not recorded
Prominent scalp veins	Not recorded
Relatively large head	Not recorded

Abnormality of limbs

Trait	How often it is seen
Fused innermost hinge joints	Always
Webbed fingers	Always
Abnormality of the wide portion of a long bone	Very often (80–99%)
Finger syndactyly	Very often (80–99%)
Fused finger bones	Very often (80–99%)
Short fingers or toes	Very often (80–99%)
Short palm	Very often (80–99%)
Thickening of shaft or central part of long bones	Very often (80–99%)
Abnormal shape of long bones of hand	Often (30–79%)
Abnormalities of the fingers	Often (30–79%)
Elbow ankylosis	Often (30–79%)
Fusion of upper and lower arm bones	Sometimes (5–29%)
Absent/small middle finger bone of the hand	Not recorded
Elbow flexion contracture	Not recorded
Finger joint hyperextensibility	Not recorded
Flared wide portion of long bone	Not recorded
Inability to straighten knee	Not recorded
Webbed fingers or toes	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Broad collarbone	Always
Broad ribs	Always
Delayed bone maturation	Always
Double-Jointed	Always
Abnormal cortical bone morphology	Very often (80–99%)
Absent collarbone	Very often (80–99%)
Harder, denser, fracture-prone bones	Very often (80–99%)
Increased bone mineral density	Very often (80–99%)
Hunched back	Sometimes (5–29%)
Limitation of joint mobility	Sometimes (5–29%)
Low muscle tone	Sometimes (5–29%)
Missing part of vertebrae	Sometimes (5–29%)
Scoliosis	Sometimes (5–29%)
Generalized decreased muscle tone	Not recorded

Abnormality of the nervous system

Trait	How often it is seen
Intellectual disability	Always
Global developmental delay	Very often (80–99%)
Specific learning disability	Very often (80–99%)
Decrease in size of the outer layer of the brain due to loss of brain cells	Often (30–79%)
Ventriculomegaly	Often (30–79%)
Absent septum pellucidum	Sometimes (5–29%)
Agenesis of corpus callosum	Sometimes (5–29%)
Dysplastic corpus callosum	Sometimes (5–29%)
Spina bifida occulta	Sometimes (5–29%)
Too much cerebrospinal fluid in the brain	Sometimes (5–29%)
IQ between 34 and 49	Not recorded

Abnormality of the integument

Trait	How often it is seen
Hanging skin	Always
Sparse hair	Always
Absent/small skin	Very often (80–99%)
Loose redundant skin	Very often (80–99%)
Prematurely aged appearance	Very often (80–99%)
Hyperconvex fingernails	Sometimes (5–29%)
Small fingernail	Sometimes (5–29%)
Thin skin	Not recorded

Abnormality of the genitourinary system

Trait	How often it is seen
Undescended testes	Always
Abnormality of the penis	Often (30–79%)
Epispadias	Often (30–79%)
Hypospadias	Often (30–79%)
Underdevelopment of external reproductive organs	Sometimes (5–29%)
Chordee	Not recorded

Growth abnormality

Trait	How often it is seen
Severe short stature	Very often (80–99%)
Faltering weight	Not recorded
Prenatal growth deficiency	Not recorded
Short stature	Not recorded

Abnormality of the digestive system

Trait	How often it is seen
Femoral hernia	Often (30–79%)
Inguinal hernia	Often (30–79%)
Anteriorly placed anus	Not recorded

Abnormality of the ear

Trait	How often it is seen
Large ears	Always
Sensorineural hearing impairment	Not recorded

Abnormality of the endocrine system

Trait	How often it is seen
Underdeveloped pituitary gland	Often (30–79%)
Decreased activity of gonads	Sometimes (5–29%)

Abnormality of the cardiovascular system

Trait	How often it is seen
Cutis marmorata	Not recorded

Abnormality of the eye

Trait	How often it is seen
Wide-set eyes	Always

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 PTDSS1 and how often each is seen. Find out more at hpo.jax.org.

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