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Novel AP3B1 compound heterozygous mutations in a Japanese patient with Hermansky–Pudlak syndrome type 2
Author(s) -
Nishikawa Takuro,
Okamura Ken,
Moriyama Mizuki,
Watanabe Kenji,
Ibusuki Atsuko,
Sameshima Seiji,
Masamoto Izumi,
Yamazaki Ieharu,
Tanita Kay,
Kanekura Takuro,
Kanegane Hirokazu,
Suzuki Tamio,
Kawano Yoshifumi
Publication year - 2020
Publication title -
the journal of dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 65
eISSN - 1346-8138
pISSN - 0385-2407
DOI - 10.1111/1346-8138.15177
Subject(s) - hermansky–pudlak syndrome , oculocutaneous albinism , immunology , compound heterozygosity , degranulation , hemophagocytic lymphohistiocytosis , platelet , chédiak–higashi syndrome , medicine , bleeding diathesis , pathology , biology , disease , lung , albinism , genetics , mutation , gene , receptor , pulmonary fibrosis
Hermansky–Pudlak syndrome type 2 (HPS2) is an extremely rare autosomal recessive inherited disease characterized by partial oculocutaneous albinism (OCA), bleeding diathesis due to a storage pool deficiency and immunodeficiency. The disorder is caused by disruption of the adapter protein 3 complex, which is involved in impaired intracellular vesicle transport. Here, we report the first case of a 1‐year‐old girl with HPS2 in Asia. She had no specific symptoms other than OCA and neutropenia. We analyzed her platelet function using transmission electron microscopy and a platelet aggregation test, cytotoxic degranulation assay of her natural killer (NK) cells and bleeding time, the results of which led to the diagnosis of HPS2. Although her NK‐cell cytotoxic degranulation was impaired, she had not developed signs of hemophagocytic lymphohistiocytosis (HLH) or fibrosing lung disease. Molecular genetic analyses showed novel heterozygous mutations (c.188T>A [p.M63K] and c.2546>A [p.L849X]) in AP3B1 . When examining patients with OCA, blood tests should be performed to confirm neutrophil count, bleeding time and platelet agglutination. When HPS2 is suspected, detailed immunological tests should be considered, and attention should be paid to HLH and pulmonary lesions immediately and over the long term.