First case report of hemophilia B Leyden in Japan.
Hemophilia B Leyden is a unique subtype of hemophilia B, characterized by increasing factor IX activity (FIX:C) after puberty and a lower normal range of FIX:C throughout adulthood. However, to date, no Japanese case has been reported. Here, we report a case of hemophilia B Leyden in a 22-year-old male. He suffered from subgaleal hematoma, and was subsequently diagnosed with hemophilia B (FIX:C 0.2%) in the neonatal period. Both his parents are Japanese. There was no history of hemophilia in his family. FIX:C gradually increased with age (8% at age = 1; 14% at age = 7; 19% at age = 12; 32% at age = 18). FIX:C is within the range 30-40% in recent several years. He once required administration of FIX concentrate against traumatic tongue bleeding at 7 years of age. Genotyping analysis of FIX was performed after informed consent at 21 years of age, and a point mutation (c.-35G>A) was detected. This mutation has been reported previously as the Leyden mutation. Although it has been reported that hemophilia B Leyden is seen in 1.9% of patients with hemophilia B, the present case is the first report of hemophilia B Leyden from Japan.
Department of Pediatrics, St. Marianna University School of Medicine, 2-16-1, Sugao, Miyamae, Kawasaki, Kanagawa, Japan. a2yamashita@marianna-u.ac.jp.
Atsuki
http://orcid.org/0000-0001-6844-5725
A
Yamashita
Department of Pediatrics, St. Marianna University School of Medicine, 2-16-1, Sugao, Miyamae, Kawasaki, Kanagawa, Japan.
Chiai
C
Nagae
Department of Pediatrics, St. Marianna University School of Medicine, Yokohama City Seibu Hospital, Yokohama, Kanagawa, Japan.
Mika
M
Mori
Department of Pediatrics, St. Marianna University School of Medicine, 2-16-1, Sugao, Miyamae, Kawasaki, Kanagawa, Japan.
Tomoko
T
Ashikaga
Department of Pathophysiological Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Tetsuhito
T
Kojima
Department of Pediatrics, St. Marianna University School of Medicine, Yokohama City Seibu Hospital, Yokohama, Kanagawa, Japan.
Masashi
M
Taki
D001777:Blood Coagulation; D001780:Blood Coagulation Tests; D004252:DNA Mutational Analysis; D005164:Factor IX / Q000235:genetics*; D005500:Follow-Up Studies; D002836:Hemophilia B / Q000097:blood / Q000175:diagnosis* / Q000235:genetics*; D006801:Humans; D007564:Japan; D008297:Male; D009154:Mutation; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D055815:Young Adult
C064567:factor IX Leyden; D005164:Factor IX
Hemophilia B; Japanese; Leyden mutation