Identification of heterozygous p.Y150C and p.V274M mutations in the HJV gene in a Japanese patient with a mild phenotype of juvenile hemochromatosis: A case report

Juvenile hemochromatosis (JH) is known as a progressive iron-storage disease, and causes severe organ impairments, including cardiomyopathy and liver cirrhosis. However, JH is a rare genetic disorder, and information for genetic mutations and phenotypes is limited. Here, we report a case of JH with heterozygous p.Y150C and p.V274M mutations in the HJV gene. A 39-year-old Japanese man was referred to Kurume University Hospital, Kurume, Japan, for fatigue and liver injury, which first appeared at the age of 25 years. There was no history of alcohol abuse and medication, and viral hepatitis, autoimmune liver diseases, and Wilson's disease were absent. However, transferrin saturation, serum ferritin, and fasting serum hepcidin levels were 98.4%, 6421 ng/mL, and 7.4 ng/mL, respectively. Furthermore, a marked reduction in signal intensity of the liver in T1/T2-weighted magnetic resonance images was seen and the R2* maps showed hepatic iron overload. Family history of hemochromatosis and severe organ impairment, such as cardiac dysfunction and diabetes mellitus, were negative. In addition, the HFE and HAMP genes did not show any mutation. However, we identified novel heterozygous p.Y150C and p.V274M mutations in the HJV gene in the patient. The p.Y150C and p.V274M mutations were seen in his mother and father, respectively. After phlebotomy, fatigue disappeared and serum transaminase levels were normalized. Furthermore, R2* maps showed a reduction of hepatic iron concentration. We first demonstrated heterozygous p.Y150C and p.V274M mutations in the HJV gene of patients with a mild JH phenotype. Thus, genetic testing should be considered even in patients with a mild phenotype of hemochromatosis.