Hermansky Pudlak Syndrome
What Is Hermansky Pudlak Syndrome?
Hermansky Pudlak Syndrome is characterized by a condition known as oculocutaneous albinism, a disorder that is caused by pigmentation or an abnormal coloration of the skin, hair, skin and eyes. Affected individuals typically have white or light-colored hair and fair skin. Patients with this disorder have higher chances of skin damage and are more exposed to different types of skin cancers that can be about due to long-term exposure to sunlight.
The oculocutaneous condition is accompanied by reduced pigmentation of the iris which is the colored part of the human eye. The same effects are also felt in the light-sensitive regions of the eye or retina. Characteristics such as involuntary eye movements (nystagmus), reduced eye vision, photophobia, and increased sensitivity to light are evident in patients diagnosed with the Hermansky Pudlak syndrome and are stable after early childhood.
Patients with the Hermansky Pudlak syndrome also suffer from blood coagulation that causes problems during the blood clotting process. Coagulation leads to prolonged bleeding and easy bruising.
Some of the patients suffering from the disorder also experience difficulties in their breathing due to a lung complication is known as pulmonary fibrosis. The disease is responsible for causing scar tissues in the lungs. The symptoms accompanying the disorder are clearly visible in the early thirties of an individual and tend to worsen with age rapidly. People diagnosed with the Hermansky Pudlak syndrome and who unluckily also develop pulmonary fibrosis, do not live for more than a decade after they start experiencing breathing difficulties.
Less common symptoms of the Hermansky Pudlak syndrome include kidney failure and inflammation of the colon, a condition called granulomatous colitis.
Symptoms
In essence, Hermansky Pudlak is a rare, hereditary disease that is mainly signaled by albinism with visual impairment, and platelet failure that causes prolonged bleeding. Some few patients experience colitis, lung fibrosis, or an abnormal storage of ceroid lipofuscin (fatty-like substance) in various parts of the body.
The primary and perhaps the most notable symptoms of the Hermansky Pudlak syndrome include bleeding gums, nose bleeds, easy bruising, and excessive bleeding after accidents, medical operations or surgery. Other classic features of the disorder include dysfunction of the platelets and reduced pigmentation in the hair, skin, and eyes.
The hair, skin, and eyes of a person suffering from Hermansky Pudlak syndrome may differ from one person to another with colors varying very pale to almost normal coloring. Eyesight is almost completely impaired with visual acuities of 20/200 or worse, that is, legally blind.
The blood storage dysfunction causes excessive bleeding, especially in females during menstruation. The bleeding is massive and may at times be life-threating if used together with aspirins. Approximately a sixth of the patients suffering from HPS develop inflammation of the colon, with excessive bleeding. Patients with advanced complications can develop pulmonary fibrosis that leads to death in their thirties, forties, or fifties.
Accumulation of fatty deposits such as ceroid lipofuscin may occur in the lungs, and other body tissues such as kidney, heart, and colon and are a probable cause of the above-mentioned symptoms.
Causes
Hermansky Pudlak is a genetic disorder that is inherited as an autosomal recessive genetic disease. Mutation in one of these nine genes HPS1, HPS3, HPS4, HPS6, HPS5, AP3B1, BLOC1S3, DTNBP1, and PLDN causes the disorder. Researchers think that the abnormality in the formation or development of lysosome-like vesicles in the cells is the leading cause of the disease. Humans inherit the genes from both parents.
In recessive disorders, the condition does not show unless a defective gene is passed from each parent. If an individual has one normal gene and one defective gene, he will be a carrier and will never portray any symptoms of the disease. In case both parents are carriers of the disease, the transmission risk to a child is 25%, the risk that the child will be a carrier is 50%, and the risk that the child will inherit two normal genes is 25%. The risk is same across all pregnancies.
Target Population
Hermansky Pudlak syndrome affects both male and female in equal numbers but is very rare. It is most prevalent in Puerto Rico where it affects one individual in every 1,800 people. One in every 21 northwest Puerto Rican descent is believed to be type 1 gene carriers. However, the disorder also occurs in other populations but is the rare and rates as the third most prevalent form of albinism.
Related Infections
Symptoms of other diseases can easily be confused to those of Hermansky Pudlak syndrome. To avoid confusion, comparisons are useful in differential diagnosis:
Oculocutaneous form of albinism is a group of genetic disorders that are characterized by reduced pigmentation of the hair, skin, and eyes. The syndrome is closely associated with eye defects. This form of albinism can lead to abnormal light sensitivity, nearsightedness, abnormal eye movements, or crossed eyes. Patients with the disease are more susceptible to skin cancer after prolonged exposure to sunlight.
Chediak-Higashi syndrome is another form of albinism that is also marked by eye problems, decreased skin pigmentation, white blood cell abnormalities, and increased susceptibility to other infections and a particular blood cancer. The disorder is also hereditary.
Treatment
Most genetic disorders are caused by gene changes in the body cells. This implies that the condition is incurable as it affects many body systems. However, there are certain precautionary measures that can be taken to manage the sign and symptoms of the disease.
For some genetic conditions that are caused by errors encountered during metabolism that results from genetic alterations that produce specific enzymes, treatment may sometimes entail replacing the missing enzyme or changing the diet.
Limiting what you eat reduces the buildup of harmful substances that are broken down by enzymes. Enzyme replacement therapy is essential in addressing enzyme shortages. Remember, these treatment options are only used to manage existing symptoms of the disorder and prevent future complications.
Other forms of treatment include transfusion of blood platelets to aid in clotting in case of excessive bleeding. Women with menorrhagia can be treated using oral contraceptives. Patients with excessive bleeding can be administered with the drug desmopressin acetate (DDAVP) to reduce the bleeding. Also, patients with the disorder should refrain from using blood coagulants such as aspirin to avoid future complications.
Genetic counseling, as well as supportive and symptomatic treatment options, benefit and offer relief to both the affected individuals and their families.
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References
- Bultema JJ, Ambrosio AL, Burek CL, Di Pietro SM. BLOC-2, AP-3, and AP-1 proteins function in concert with Rab38 and Rab32 proteins to mediate protein trafficking to lysosome-related organelles. J Biol Chem. 2012 Jun 1;287(23):19550-63. doi: 10.1074/jbc.M112.351908. Epub 2012 Apr 16.Citation on PubMed or Free article on PubMed Central
- Bultema JJ, Di Pietro SM. Cell type-specific Rab32 and Rab38 cooperate with the ubiquitous lysosome biogenesis machinery to synthesize specialized lysosome-related organelles. Small GTPases. 2013 Jan-Mar;4(1):16-21. doi: 10.4161/sgtp.22349. Epub 2012 Dec 17. Review.Citation on PubMed or Free article on PubMed Central
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- Gerondopoulos A, Langemeyer L, Liang JR, Linford A, Barr FA. BLOC-3 mutated in Hermansky Pudlak syndrome is a Rab32/38 guanine nucleotide exchange factor. Curr Biol. 2012 Nov 20;22(22):2135-9. doi: 10.1016/j.cub.2012.09.020. Epub 2012 Oct 18.Citation on PubMed or Free article on PubMed CentralOMIM: HERMANSKY PUDLAK SYNDROME 1
- Huizing M, Helip-Wooley A, Westbroek W, Gunay-Aygun M, Gahl WA. Disorders of lysosome-related organelle biogenesis: clinical and molecular genetics. Annu Rev Genomics Hum Genet. 2008;9:359-86. doi: 10.1146/annurev.genom.9.081307.164303. Review.Citation on PubMed or Free article on PubMed Central
