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group_4_presentation_3_-_albinism [2018/11/30 22:29] baruaa1 [Symptoms] |
group_4_presentation_3_-_albinism [2018/11/30 23:02] (current) baruaa1 [Symptoms] |
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| ===== Albinism ===== | ===== Albinism ===== | ||
| {{ :05-05-2015albinism.jpg?400 |}} | {{ :05-05-2015albinism.jpg?400 |}} | ||
| + | Retrieved from: https://global.unitednations.entermediadb.net/assets/mediadb/services/module/asset/downloads/preset/assets/2015/05/21761/image300x180cropped.jpg | ||
| ===== Introduction ===== | ===== Introduction ===== | ||
| - | Albinism is characterized as the absence of pigmentation found throughout the body. It is a congenital disorder meaning that it’s effects can be seen from birth, and it can affect both plants as well as animals, ranging from humans to reptiles as an example. In humans, albinism causes changes to the colour of the eyes, skin, and hair, which appear lighter in colour (Albinism, 2018). Some of the symptoms that appear with albinism include a number of vision defects, as well as increased rates of sunburning and skin cancer due to a lack of skin pigmentation (Albinism, 2018). In some rare cases, Albinism may also cause deficiency in immune function and increase the rates of certain infections (Albinism, 2018). | + | Albinism is characterized as the absence of pigmentation found throughout the body. It is a congenital disorder meaning that its effects can be seen from birth, and it can affect both plants as well as animals, ranging from humans to reptiles as an example. In humans, albinism causes changes to the colour of the eyes, skin, and hair, which appear lighter in colour (Albinism, 2018). Some of the symptoms that appear with albinism include a number of vision defects, as well as increased rates of sunburning and skin cancer due to a lack of skin pigmentation (Albinism, 2018). In some rare cases, Albinism may also cause a deficiency in immune function and increase the rates of certain infections (Albinism, 2018). |
| - | Albinism is a recessive genetic disorder and results from inheritance of two alleles containing the mutation. However, due to its recessive nature, the parents of the offspring may or may not be displaying the phenotype while being carriers of the mutated alleles (Albinism, 2018). Albinism occurs due to a mutation that codes for the enzyme tyrosinase, where it is either absent or defective. Tyrosinase is involved in the production of melanin (Albinism, 2018). | + | Albinism is a recessive genetic disorder and results from the inheritance of two alleles containing the mutation. However, due to its recessive nature, the parents of the offspring may or may not be displaying the phenotype while being carriers of the mutated alleles (Albinism, 2018). Albinism occurs due to a mutation that codes for the enzyme tyrosinase, where it is either absent or defective. Tyrosinase is involved in the production of melanin (Albinism, 2018). |
| ===== Epidemiology ===== | ===== Epidemiology ===== | ||
| - | The epidemiology of albinism is still poorly understood, but studies have demonstrated that incidence varies from region to region, and does not preferentially affect one sex over another. In Africa, albinism has an incidence rate of 1 in 4000-5000. In Europe, the incidence rate is roughly 1 in 20,000. In China, the incidence rate is 1 in 18,000. In the United States, the incidence rate is 1 in 16,000. However, incidence rate has been shown to change based on population and genetics, one example is the American Indian Hopi tribe from Arizona which has a much higher incidence rate compared to the rest of the country (1 in 227). Thus, demonstrating that this disease is largely genetic in nature (Kromberg, 2018). | + | The epidemiology of albinism is still poorly understood, but studies have demonstrated that incidence varies from region to region, and does not preferentially affect one sex over another. In Africa, albinism has an incidence rate of 1 in 4000-5000. In Europe, the incidence rate is roughly 1 in 20,000. In China, the incidence rate is 1 in 18,000. In the United States, the incidence rate is 1 in 16,000. However, the incidence rate has been shown to change based on population and genetics, one example is the American Indian Hopi tribe from Arizona which has a much higher incidence rate compared to the rest of the country (1 in 227). Thus, demonstrating that this disease is largely genetic in nature (Kromberg, 2018). |
| The prevalence of types of albinism also vary by ethnic group and location. For example, in the United States, OCA2 is the most common form of albinism and disproportionately affects African Americans and Africans. The estimated frequency is 1 in 10,000 in African-Americans compared with caucasians being 1 in 36,000 (Bashour, 2018). | The prevalence of types of albinism also vary by ethnic group and location. For example, in the United States, OCA2 is the most common form of albinism and disproportionately affects African Americans and Africans. The estimated frequency is 1 in 10,000 in African-Americans compared with caucasians being 1 in 36,000 (Bashour, 2018). | ||
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| Lastly, if the patient exhibits eye symptoms that match the phenotype of individuals with ocular albinism (OA 1), females need to be checked for carrier status (Carden, Boissy, Schoettker, & Good, 1998). This status is indicated by a mud-splattered fundus (Carden, Boissy, Schoettker, & Good, 1998). Next, a skin histology examination can be taken to detect macromelanosomes, known as giant melanosomes in pigmented skin lesions (Carden, Boissy, Schoettker, & Good, 1998). | Lastly, if the patient exhibits eye symptoms that match the phenotype of individuals with ocular albinism (OA 1), females need to be checked for carrier status (Carden, Boissy, Schoettker, & Good, 1998). This status is indicated by a mud-splattered fundus (Carden, Boissy, Schoettker, & Good, 1998). Next, a skin histology examination can be taken to detect macromelanosomes, known as giant melanosomes in pigmented skin lesions (Carden, Boissy, Schoettker, & Good, 1998). | ||
| - | {{ :screen_shot_2018-11-30_at_5.06.44_pm.png?nolink&300 |}} | + | {{ :screen_shot_2018-11-30_at_5.06.44_pm.png?nolink&300 |}} |
| **Figure 2:** Histology from skin biopsy displaying macromelanosomes (Shiono, Tsunoda, Chida, Nakazawa, & Tamai, 1995). | **Figure 2:** Histology from skin biopsy displaying macromelanosomes (Shiono, Tsunoda, Chida, Nakazawa, & Tamai, 1995). | ||
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| + | {{ :screen_shot_2018-11-30_at_10.41.43_pm.png?nolink&300 |}} | ||
| + | **Figure 3:** Indication of a mud-splattered fundus (Shiono, Tsunoda, Chida, Nakazawa, & Tamai, 1995). | ||
| ===== Pathophysiology and Mechanisms ===== | ===== Pathophysiology and Mechanisms ===== | ||
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| {{ :bjophthalmol-1998-february-82-2-189-f1.medium.gif?300 |}} | {{ :bjophthalmol-1998-february-82-2-189-f1.medium.gif?300 |}} | ||
| - | **Figure 3:** The biosynthesis of melanin, including the three important catalyzing reactions of tyrosinase (Carden, Boissy, Schoettker, & Good, 1998). | + | **Figure 4:** The biosynthesis of melanin, including the three important catalyzing reactions of tyrosinase (Carden, Boissy, Schoettker, & Good, 1998). |
| __OCA2:__ It is caused by a mutation in the human P-gene (Puri, Gardner & Brilliant, 2000). The function of the gene product of this gene is not fully known. However, it is thought that the P-protein maintains the right PH of melanosomes (acidification) and also targets necessary molecules that are involved in the production of melanin such as tyrosine, into the melanosome (Puri, Gardner & Brilliant, 2000). Therefore without this protein, the PH levels of the melanosome will no longer be maintained and the transportation of tyrosine into the melanosome to produce melanin, will be compromised (Puri, Gardner & Brilliant, 2000). | __OCA2:__ It is caused by a mutation in the human P-gene (Puri, Gardner & Brilliant, 2000). The function of the gene product of this gene is not fully known. However, it is thought that the P-protein maintains the right PH of melanosomes (acidification) and also targets necessary molecules that are involved in the production of melanin such as tyrosine, into the melanosome (Puri, Gardner & Brilliant, 2000). Therefore without this protein, the PH levels of the melanosome will no longer be maintained and the transportation of tyrosine into the melanosome to produce melanin, will be compromised (Puri, Gardner & Brilliant, 2000). | ||
| {{ :1-s2.0-s0022202x15410085-gr1.jpg?300 |}} | {{ :1-s2.0-s0022202x15410085-gr1.jpg?300 |}} | ||
| - | **Figure 4:** a) A functioning melanosome (m) producing melanin. (b,c,d) A mutated P protein causing a deficiency of melanin production in the melanosome (m) (Puri, Gardner & Brilliant, 2000). | + | **Figure 5:** a) A functioning melanosome (m) producing melanin. (b,c,d) A mutated P protein causing a deficiency of melanin production in the melanosome (m) (Puri, Gardner & Brilliant, 2000). |
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| {{ ::screen-shot-2018-01-25-at-14.47.24.png?300 |}} | {{ ::screen-shot-2018-01-25-at-14.47.24.png?300 |}} | ||
| - | **Figure 5:** The biosynthesis of melanin, highlighting the important role of TRP-1 protein in regulating the production of black melanin ("Facial hyperpigmentation in skin of colour: PRIME Journal", 2018). | + | **Figure 6:** The biosynthesis of melanin, highlighting the important role of TRP-1 protein in regulating the production of black melanin ("Facial hyperpigmentation in skin of colour: PRIME Journal", 2018). |
| ===== Albinism and Skin Cancer ===== | ===== Albinism and Skin Cancer ===== | ||
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| {{ :albinism.jpg?900 |}} | {{ :albinism.jpg?900 |}} | ||
| - | **Figure 6:** Incidence of albinism in most prevalent countries (Kromberg, 2018) | + | **Figure 7:** Incidence of albinism in most prevalent countries (Kromberg, 2018) |
| In Africa, the incidence of squamous cell carcinoma in normally pigmented population ranges from 7.8 – 16% of all diagnosed skin malignancies. Whereas in the African albino population, the risk of developing these cancers has been reported to be almost 1000-fold (Mabula et al., 2012). From available studies, it was found that skin cancers in albinos are preventable. This can be done through various skin protective measures such as sun-screening agents, protective clothing, reducing time spent outdoor and early treatment (Yurtoğlu, 2010). The lack of information on the connection between albinism and skin cancer plays a major role in worsening this situation. To address this, the public (especially those with albinism) should be educated on early institution of preventive measures. In addition, the government should provide treatment funds for albinos with low socioeconomic status to reduce the high rates of skin cancer among albinos (Mabula et al., 2012). | In Africa, the incidence of squamous cell carcinoma in normally pigmented population ranges from 7.8 – 16% of all diagnosed skin malignancies. Whereas in the African albino population, the risk of developing these cancers has been reported to be almost 1000-fold (Mabula et al., 2012). From available studies, it was found that skin cancers in albinos are preventable. This can be done through various skin protective measures such as sun-screening agents, protective clothing, reducing time spent outdoor and early treatment (Yurtoğlu, 2010). The lack of information on the connection between albinism and skin cancer plays a major role in worsening this situation. To address this, the public (especially those with albinism) should be educated on early institution of preventive measures. In addition, the government should provide treatment funds for albinos with low socioeconomic status to reduce the high rates of skin cancer among albinos (Mabula et al., 2012). | ||
| {{ :albinism1.jpg?300 |}} | {{ :albinism1.jpg?300 |}} | ||
| - | **Figure 7:** An image of squamous cell carcinoma on the head of a patient (Yurtoğlu, 2010) | + | **Figure 8:** An image of squamous cell carcinoma on the head of a patient (Yurtoğlu, 2010) |
| ===== Treatment ===== | ===== Treatment ===== | ||
| Albinism is both congenital and genetic, meaning that it is present for birth and cannot be cured. However, many of its symptoms can be treated. | Albinism is both congenital and genetic, meaning that it is present for birth and cannot be cured. However, many of its symptoms can be treated. | ||
