Congenital Erythropoietic Porphyria
CEP, also known as Gunther disease, is caused by a deficiency of the enzyme uroporphyrinogen III synthase (URO-synthase) in the heme biosynthesis pathway due to mutations, or changes, in the UROS gene. The disorder is autosomal recessive. CEP is one of the most severe porphyrias, symptoms usually begin soon after birth or in early childhood. Some severe cases have been diagnosed before birth as a cause of anemia and fluid accumulation in the fetus (fetal hydrops). Less severe cases may occur in adults in association with another bone marrow condition.
Skin photosensitivity results in severe blistering and scarring, often with mutilation and loss of facial features and fingers. Increased hair growth (hypertrichosis) on sun-exposed skin, brownish-colored teeth (erythrodontia), and reddish-colored urine are common. There may be bone fragility due to expansion of the bone marrow and vitamin deficiencies, especially vitamin D. Red blood cells have a shortened life-span, and mild or severe hemolytic anemia often results. Synthesis of heme and hemoglobin is actually increased to compensate for the shortened red blood cell survival and is associated with splenomegaly. Bacteria may infect the damaged skin and contribute to mutilation and scarring.
DNA analysis of the UROS gene is performed by full gene sequencing of all exons (coding regions), 20-30 base pairs into the introns (including splice sites), and the promoter region. This methodology should identify >99% of gene mutations listed in the Human Gene Mutation Database as well as novel mutations as well as novel mutations. Molecular analysis of ALAS2 exon 11 (for XLP) is performed in conjunction with full sequencing of the UROS gene.
Targeted mutation analysis can be performed for family members of individuals whose UROS gene mutations have been identified previously. Documentation of the family's mutations must be provided.
Prenatal diagnosis is also available. Prior to ordering prenatal testing, please contact our laboratory at 212-241-7518.
- Full DNA analysis: 20 ml of whole blood in EDTA (anticoagulant) tubes (lavender top) OR extracted DNA (50 ?l with concentration of 200ng/?l).
- Targeted Mutation Analysis: 20ml of whole blood in EDTA (anticoagulant) tubes (lavender top) OR extracted DNA (30 ?l with concentration of 200ng/?l) OR buccal cells (buccal brushes MUST be requested from laboratory).
Testing requires prior documentation of parental mutation.
- Chorionic Villi: 5-10 mg in conical tube with sterile saline OR transport media
- Amniotic Fluid: 10 ml in conical tube
- Cultured Cells: two confluent T-25 flasks
Additionally, please send:
- 5-10 ml maternal blood in EDTA (lavender top) required to perform MCC studies on all prenatal samples and in case maternal confirmation studies are necessary
- 5-10 ml paternal blood in EDTA (lavender top) in case paternal confirmation studies are necessary
Shipping: Ship at room temperature.
Post-natal: 10-14 days
Prenatal: 3-5 days
Full gene sequencing: 81405, 81479, G0452
Targeting mutation analysis: 81404, 81479, G0452
Consent Form: Porphyria Genetic Testing Consent [PDF]
Requisition Form: Porphyria Testing Requisition [PDF]