Traits

Traits linked to PYGL

glycogen phosphorylase L

The Human Phenotype Ontology links 33 traits to PYGL, by body system: features seen in people with one of the gene's rare conditions.

Laboratory abnormality

Trait	How often it is seen
High liver enzymes	Always
Increased hepatic glycogen content	Always
High levels of ketone bodies	Often (30–79%)
Low blood sugar	Often (30–79%)
Elevated lipids in blood	Sometimes (5–29%)
Intermittent lactic acidemia	Sometimes (5–29%)
High urine protein levels	Rarely (1–4%)
Postprandial hyperlactemia	Rarely (1–4%)
Elevated serum cholesterol	Not recorded
Increased plasma triglycerides	Not recorded
Reduced hepatic glycogen phosphorylase activity	Not recorded

Abnormality of the digestive system

Trait	How often it is seen
Enlarged liver	Always
Abdominal bloating	Sometimes (5–29%)
Hepatic fibrosis	Sometimes (5–29%)
Portal fibrosis	Sometimes (5–29%)
Hepatocellular carcinoma	Rarely (1–4%)
Scar tissue replaces healthy tissue in the liver	Rarely (1–4%)

Growth abnormality

Trait	How often it is seen
Faltering weight	Often (30–79%)
Growth delay	Often (30–79%)
Short stature	Sometimes (5–29%)
Faltering weight in infancy	Not recorded
Growth delay as children	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Osteopenia	Often (30–79%)
Osteoporosis	Often (30–79%)
Exercise-induced muscle cramps	Sometimes (5–29%)
Low muscle tone	Sometimes (5–29%)

Abnormality of the nervous system

Trait	How often it is seen
Difficulty sleeping	Sometimes (5–29%)
Irritability	Sometimes (5–29%)
Motor delay	Sometimes (5–29%)

Abnormality of the cardiovascular system

Trait	How often it is seen
Enlarged and thickened heart muscle	Rarely (1–4%)

Abnormality of the endocrine system

Trait	How often it is seen
Delayed puberty	Often (30–79%)

Abnormality of the genitourinary system

Trait	How often it is seen
Abnormality of the kidney	Rarely (1–4%)

Constitutional symptom

Trait	How often it is seen
Postexertional symptom exacerbation	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 PYGL and how often each is seen. Find out more at hpo.jax.org.

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