Oculocutaneous albinism (OCA) could be either non-syndromic or syndromic. There are significant challenges in clinically recognizing and differentiating Hermansky-Pudlak syndrome (HPS) from non-syndromic OCA.
In a prospective consecutive case series, 63 patients (less than 18 years old) with a molecular genetic diagnosis of albinism (except OCA1A), Ocular albinism (OA) and Hermansky-Pudlak syndrome seen over a 3-year period were evaluated and analyzed. Hair colour, iris colour was graded, compared and correlated with the degree of fundus pigmentation and foveal development.
A total of 63 patients were evaluated. Forty-five patients had non-syndromic OCA (11 OCA1B, 24 OCA2, 9 OCA4, and 1 OCA6), 5 patients had OA and 13 patients had HPS. All 3 BLOC-related HPS categories were seen (1 with BLOC1, 7 with BLOC-2 and 5 with BLOC-3 related HPS). All patients with OA were hyperopic, had darker fundus pigmentation, but had poor foveal development. All HPS patients had lighter fundus pigmentation. The degree of fundus pigmentation correlated positively with the iris pigmentation and also with the foveal development only in OCA2.
Careful observation of the phenotype by comparison of the skin, hair, iris colour, with the degree of fundus pigmentation and foveal development may help clinically differentiate HPS from OCA patients of Chinese ethnicity even in the absence of any bleeding tendency.

BACKGROUND: The Hermansky-Pudlak syndrome (HPS) is an autosomal recessive rare disorder characterized by oculocutaneous albinism, bleeding diathesis, chronic granulomatous colitis and/or pulmonary fibrosis. HPS is the most common single-gene disorder in Puerto Rico with a prevalence of 1:1,800 in the Northwest of the island. Risk of menorrhagia and post-partum hemorrhage (PPH) in cases of women with HPS have been described in the medical literature, but data regarding comprehensive description of bleeding diathesis remains lacking. For this reason, we aim to identify bleeding events using the International Society on Thrombosis and Hemostasis Bleeding Assessment Tool (ISTH-BAT), a standardized quantitative tool that translates the range of severity of bleeding symptoms into a cumulative bleeding score (BS).
OBJECTIVE: To use the ISTH-BAT in HPS in order to describe bleeding symptoms and allow for comparison with other inherited bleeding disorders.
METHODS: Puerto Rican females and adult participants with HPS based on genetic linkage were enrolled. The ISTH-BAT was administered and results were identified using descriptive statistical analysis.
RESULTS: Questionnaire answers of twelve women with HPS-1 and HPS-3 were evaluated. Participants\' mean BS was HPS-1 (11.4) and HPS-3 (8.0) Participants with HPS-1 and HPS-3 reported abnormal bleeding events that presented during dental extractions, menorrhagia, surgical interventions, gastrointestinal, oral cavity and post-partum. Patients with history of pulmonary fibrosis (PF) showed a higher mean bleeding score than those who had no history of PF.
CONCLUSIONS: Female patients with HPS type 1 and 3 experienced abnormal bleeding events according to the ISTH-BAT bleeding score. Bleeding medications were inconsistently used and varied independently from healthcare professionals. The benefits of this study were to understand the history of bleeding complications in patients with HPS type 1 and 3 using an international validated system. The results of this study will help design strategies to improve the care we provide to this population.

The Hermansky Pudlak syndromes (HPS) constitute a family of disorders characterized by oculocutaneous albinism and bleeding diathesis, often associated with lethal lung fibrosis. HPS results from mutations in genes of membrane trafficking complexes that facilitate delivery of cargo to lysosome-related organelles. Among the affected lysosome-related organelles are lamellar bodies (LB) within alveolar type 2 cells (AT2) in which surfactant components are assembled, modified, and stored. AT2 from HPS patients and mouse models of HPS exhibit enlarged LB with increased phospholipid content, but the mechanism underlying these defects is unknown. We now show that AT2 in the pearl mouse model of HPS type 2 lacking the adaptor protein 3 complex (AP-3) fails to accumulate the soluble enzyme peroxiredoxin 6 (PRDX6) in LB. This defect reflects impaired AP-3-dependent trafficking of PRDX6 to LB, because pearl mouse AT2 cells harbor a normal total PRDX6 content. AP-3-dependent targeting of PRDX6 to LB requires the transmembrane protein LIMP-2/SCARB2, a known AP-3-dependent cargo protein that functions as a carrier for lysosomal proteins in other cell types. Depletion of LB PRDX6 in AP-3- or LIMP-2/SCARB2-deficient mice correlates with phospholipid accumulation in lamellar bodies and with defective intraluminal degradation of LB disaturated phosphatidylcholine. Furthermore, AP-3-dependent LB targeting is facilitated by protein/protein interaction between LIMP-2/SCARB2 and PRDX6 in vitro and in vivo Our data provide the first evidence for an AP-3-dependent cargo protein required for the maturation of LB in AT2 and suggest that the loss of PRDX6 activity contributes to the pathogenic changes in LB phospholipid homeostasis found HPS2 patients.