Doss porphyria

Signs and symptoms

The clinical presentation includes a wide range of neurologic and gastrointestinal symptoms. The disease can present during early childhood or adulthood with acute neurologic symptoms resembling those of acute intermittent porphyria. Gastrointestinal symptoms during acute attacks include abdominal cramping, vomiting, and constipation, which can lead to failure to thrive and poor weight gain in children. Other acute attack features include rapid heart rate, high blood pressure, and respiratory difficulties.

Attacks may last weeks and are termed neurovisceral due to associated neurological complications. Patients have reported numbness, tingling, seizures, burning pain, poor coordination, muscle paralysis, and psychological disturbances; psychosis has occurred in severe instances. Triggers include fasting, low-carb diet, dehydration, alcohol, estrogen or progesterone use, certain drugs, and mental or physical stressors.

Diagnosis

Diagnosis requires consideration of presenting symptoms and patient history along with biomarker testing in urine or blood. Key biomarkers include urine porphobilinogen (PBG), aminolevulinic acid (ALA), and porphyrins in blood and urine.

PBG levels fluctuate and are best measured at symptom onset; ALA levels are elevated in ADP and correlate with disease severity. If porphyrin levels are significantly elevated, DNA testing for mutations in the ALAD gene is the most specific diagnostic method. Lead poisoning and tyrosinemia type I (via succinylacetone) also inhibit ALAD and should be considered.

Did You Know?

• Supportive care and symptom treatment are typical management options; during acute attacks, glucose supplementation and intravenous hematin are mainstays.
• Avoiding physical and psychological stressors has been shown to limit recurrence of attacks.
• The condition theoretically affects males and females at the same rate, though all reported cases have been in males.