Patients typically receive a diagnosis of HPS following an unexplained bleeding episode that prompts doctors to investigate further and to test for HPS. The vast majority of people who eventually get a diagnosis of HPS have previously been misdiagnosed as having either a subtype of oculocutaneous or ocular albinism
In the UK, a diagnosis of OCA or OA is typically given by either an ophthalmologist (eye doctor) or a paediatrician (children's doctor). This is because they are typically the type of doctor that a newborn or child is referred to when albinism is suspected. HPS is rare and most doctors have never heard of it so when they see a lack of pigment (hypo-
Typically a doctor will make a diagnosis of either OCA or OA based upon level of hypopigmentation and examination of eyes. This causes problems because both HPS and other forms of albinism share some characteristics. The tests and criteria used to diagnose OCA and OA focus on those shared characteristics and so cannot be used to reliably differentiate between HPS and the various other subtypes of OCA and OA These include:
Some doctors make an incorrect assumption the people with HPS have darker pigmentation than people with OCA-
In fairness most doctors have the very best of intentions for their patients. It is sometimes the case that patients are not best placed to help doctors come to a correct diagnosis. For instance:
People with HPS are Tyrosinase positive (Tye+). This means they have an enzyme called Tyrosinase in particular types of skin and hair cells that are involved in the production of the pigment Melanin. This is also true of people who have the various subtypes of OCA and OA -
Historically some doctors have used microscopes to examine hair follicles for the presence of pigment containing Melanosomes and how ‘mature’ the melanosomes are. Again the various subtypes of HPS can give similar results to the subtypes of OCA and OA. Again this approach is regarded as unreliable and in some cases it may indicate that a patient is Ty negative when they are actually Ty positive.