X-linked erythropoietic protoporphyria
Findings
No curated finding names X-linked erythropoietic protoporphyria yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
An erythropoietic protoporphyria in which the cause of the disease is a hemizygous, heterozygous, or homozygous (rare) gain-of-function (GOF) variant (X-linked inheritance pattern) in the terminal regulatory exon of ALAS2. GOF variants increase ALAS2 activity resulting in pathway upregulation and high levels of protoporphyrin IX (PPIX). Males with hemizygous variants frequently present in early childhood with severe cutaneous photosensitivity and laboratory markers of liver disease. Heterozygous females can present with symptoms ranging from as severe as affected males to asymptomatic due to random X-chromosome inactivation. This disease is clinically indistinguishable from FECH-related erythropoietic protoporphyria.
Definition from the Mondo Disease Ontology (MONDO:0010420), read 2026-09-29. CC BY 4.0.
- Inheritance
- X-linked dominant inheritance
HPO, annotations 2026-09-02
Features
2 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Cutaneous photosensitivityHPOHP:0000992
- Increased erythrocyte protoporphyrin concentrationHPOHP:0012187
Genes
1 gene
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
- ALAS2HGNC:397
- Definitive · ClinGen · X-linked · 2022
- Strong · Genomics England PanelApp · X-linked · 2020
- Strong · Labcorp Genetics (formerly Invitae) · X-linked · 2022
- Strong · PanelApp Australia · X-linked · 2025
- Supportive · Orphanet · X-linked · 2021
Where it sits
Other names
6 names
Resolves to: X-linked erythropoietic protoporphyria
- Also called
- ALAS2-related erythropoietic protoporphyriaerythropoietic protoporphyria, X-linkedX-linked dominant erythropoietic protoporphyriaX-linked dominant protoporphyriaXLDPPXLPP