The number of reported cases of HPS-2 is small in comparison to HPS more generally.
Immuno-deficiency and a history of major infections are the dominant characteristics of HPS-2 and are the major focus of healthcare.
Very early onset of pulmonary fibrosis has been reported.
The immuno-deficiency of HPS-2 includes very reduced levels of a particular type of white blood cell called Neutrophils. The reduced neutrophil count is called neutropenia. There are reported cases of improved neutrophil counts following therapy with G-CSF (Granulocyte Colony Stimulating Factor).
Other cells of the immune system also do not function correctly, they are called Natural Killers cells and T-Lymphocytes (CD8+ clones).
Failure to thrive and developmental delay are also reported characteristics.
Bone marrow transplant and drug therapy to control the neutropenia are typically necessary.
There are several reported cases of HPS-2 where a low dense granule count is found in blood platelets - in contrast to the near complete absence of dense granules expected with the other known subtypes of HPS.
Further reading about HPS-2
Wenham, M., et al (2010). Two patients with Hermansky Pudlak syndrome type 2 and novel mutations in AP3B1. Haematological, 2010: 95 (2).
Enders, A., et al (2006). Lethal haemophagocytic lymphohistocytosis in Hermansky-Pudlak syndrome type II. Blood; 1 July 2006: Vol 108, No. 1.
Huizing, M., et al. (2002). Nonsense Mutations in AP3B3A Cause Complete Deﬁciency of the 3A Subunit of Adaptor Complex-3 and Severe Hermansky-Pudlak Syndrome Type 2. Pediatric Research (2002) 51, No. 2, 150–158.