Background The effect of Givosiran on persistent symptoms of hereditary coproporphyria (HCP) is unclear. We report 2 sisters of HCP treated with Givosiran.

Case Case 1: A 23-year-old Japanese female was diagnosed as HCP in the neonatal period. Her diagnosis was established on the base of clinical symptoms; UV-sensitization and dark-brown urine. Abdominal pain, headache, general fatigue, and photosensitization were observed and gradually worsen. He was referred to our hospital for the treatment with Givosiran at 22 years old. Excretion of coproporphyrin, d-aminolevulinic acid (ALA) and porphobilinogen (PBG) was 2927 mg/g CRE, 1.3 mg/L, and 2.7 mg/L respectively. The persistent symptoms were improved immediately and the values of coproporphyrin, ALA and PBG were decreased to 1754 mg/g CRE, 1.3 mg/L, and 0.8 mg/L respectively 4 months after Givosiran treatment.

Case 2: The patient is 12 years old girl. She had abdominal pain from 4-years-old. Abdominal pain gradually deteriorated every year, nausea, numbness in limbs, weakness, headache, dizziness, and light-headedness began to occur frequently. The skin symptoms caused by sunlight were not strong, but dizziness, abdominal pain, and headache worsened when exposed to sunlight. She diagnosed HCP by genetic analysis. She arrived at our hospital for administered Givosiran. Coproporphyrin, ALA, and PBG was 238μg/g CRE, 1.5mg/L, and 2.3mg/day respectively before Givosiran administration. After the start of Givosiran, the persistent symptoms improved immediately, and the value of Coproporphyrin, ALA, and PBG decreased to 99μg/g CRE, 0.6mg/L, and 1.0mg/L after 3 months.

Conclusion Givosiran has been shown to be effective for persistent symptoms of HCP. The changes in ALA and PBG are slight, and it is necessary to investigate the factors that contributed to the improvement of symptoms in the future.