Some commercial genetic tests are available for specific genetic mutations found in the HPS-1 and HPS-3 genes. At the current time it is known that mutations to 9 different genes can cause HPS - that leaves 7 subtypes without a genetic test. Also, not all the genetic variants of HPS have been identified. 15 subtypes of HPS have been identified in mice and it is believed a similar number will eventually be found in humans. Thus, there is still a need to carry out blood tests for HPS that look for the presence or absence of dense granules in blood platelets.
New advances in automated, ‘high throughput’, genetic sequencing are currently being evaluated in the UK and elsewhere. One such study focuses on the genetics of rare bleeding disorders including HPS and participants are currently being sought. Interested families or individuals should contact the HPS Network UK in the first instance. It is hoped that in time these advances will become commercially viable and accessible through the NHS. Increases in speed and a reduction in costs may make it possible to ‘test’ by sequencing the known HPS genes. Also, whole genomic sequencing (all genes) would make it possible to identify new genes that have a role in either causing HPS or affecting its severity.
Molecular genetic tests for the subtypes of Oculocutaneous Albinism are not a substitute for the test for Hermansky-Pudlak Syndrome.
Sometimes people are offered referral to a geneticist for genetic tests for the OCA's when, in fact, they requested to be tested for HPS. If a doctor or patient suspects HPS then it should be tested for in the first instance (along with other possible bleeding disorders) because:
HPS is NOT a stable condition and carries a risk of severe bleeding in the event of trauma or invasive medical procedures, surgery, dentistry. Due to these risks it should be tested for at the earliest possible point n the diagnostic pathway so that precautions can be taken if necessary.
Molecular genetic tests for the OCA's and OA take a long time from the point of seeing a geneticist to the point when a patient is given the results.
Genetic tests for the OCA's and OA can come back as inconclusive in which case a test for HPS might be necessary and could have been carried out in the first instance.
Molecular genetic tests for Oculocutaneous Albinism and Ocular Albinism
Molecular genetic tests are available for a number of the subtypes of oculocutaneous albinism and ocular albinism. However, these are not routinely offered to parents of children with albinism or to affected adults through the UK National Health Service (NHS).
People requesting these tests have been known to meet resistance from doctors including suggestions for why testing is not necessary. It has been suggested to some parents that it is not necessary to know precisely what subtype of OCA a child has because, for instance, ‘albinism is a stable condition and knowing what subtype a person has would not make any difference to eye and skin care, or the prescription for glasses and optical aids.
Awareness of Hermansky-Pudlak Syndrome amongst doctors is poor. For instance, many ophthalmologists, paediatricians, and geneticists do not consider it as a possible diagnosis simply because they have not heard of it.
Similarly, people can meet resistance from GP's and consultants when asking to be referred for HPS testing. Some people have been told that HPS is very rare and is mild and they do not need to worry about about it’ Again this reflects a poor understanding of both the range and variation in severity of the symptoms of HPS.