Albinisme pada haiwan

30 Rarely Seen Albino Animals From Around The World…Amazing!

These beautiful animals look as if they’ve been lifted from the pages of a mythical storybook, or transported from another world not like our own.
But, in fact, these creatures are of this world. However, they have albinism, a congenital condition defined by partial or complete absence of pigment in the skin, hair, and eyes, the lack of which makes one more susceptible to sunburn and skin disease. Have you ever seen an albino penguin? What about an albino lobster? Here’s your chance! These albino animals are so unique and beautiful to behold, but note that some of these “albinos” are rare breeds without the actual pigmentation condition.

Perihal ALBINISME - ALBINO pada manusia

 Albinisme

Albinisme disebabkan oleh kecacatan alel yang terlibat dalam  sintesis melanin. Gen bagin sintesis dipencilkan pada autosom dan mengalami mutasi. Sel pigmen pada kulit, rambut dan iris mata tidak berupaya untuk mensintesiskn melanin. Albanisme disebabkan oleh alel resesif bagi pigmentasi normal.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            

                                                                                                                                                                                                                                                                                                                                     Albinism

Definition

Albinism is an inherited condition present at birth, characterized by a lack of pigment that normally gives color to the skin, hair, and eyes. Many types of albinism exist, all of which involve lack of pigment in varying degrees. The condition, which is found in all races, may be accompanied by eye problems and may lead to skin cancer later in life.

Description

Albinism is a rare disorder found in fewer than five people per 100,000 in the United States and Europe. Other parts of the world have a much higher rate; for example, albinism is found in about 20 out of every 100,000 people in southern Nigeria.

There are 10 types of the most common form of the condition, known as "oculocutaneous albinism," which affects the eyes, hair, and skin. In its most severe form, hair and skin remain pure white throughout life. People with a less severe form are born with white hair and skin, which turn slightly darker as they age. Everyone with oculocutaneous albinism experiences abnormal flickering eye movements (nystagmus) and sensitivity to bright light. There may be other eye problems as well, including poor vision and crossed or "lazy" eyes (strabismus).

The second most common type of the condition is known as "ocular" albinism, in which only the eyes lack color; skin and hair are normal. There are five forms of ocular albinism; some types cause more problems-especially eye problems-than others.

Causes and symptoms

Every cell in the body contains a matched pair of genes, one inherited from each parent. These genes act as a sort of "blueprint" that guides the development of a fetus.

Albinism is an inherited problem caused by a flaw in one or more of the genes that are responsible for directing the eyes and skin to make melanin (pigment). As a result, little or no pigment is made, and the child's skin, eyes and hair may be colorless.

In most types of albinism, a recessive trait, the child inherits flawed genes for making melanin from both parents. Because the task of making melanin is complex, there are many different types of albinism, involving a number of different genes.

It's also possible to inherit one normal gene and one albinism gene. In this case, the one normal gene provides enough information in its cellular blueprint to make some pigment, and the child will have normal skin and eye color. They "carry" one gene for albinism. About one in 70 people are albinism carriers, with one flawed gene but no symptoms; they have a 50% chance of passing the albinism gene to their child. However, if both parents are carriers with one flawed gene each, they have a 1 in 4 chance of passing on both copies of the flawed gene to the child, who will have albinism. (There is also a type of ocular albinism that is carried on the X chromosome and occurs almost exclusively in males because they have only one X chromosome and, therefore, no other gene for the trait to override the flawed one.)

Symptoms of albinism can involve the skin, hair, and eyes. The skin, because it contains little pigment, appears very light, as does the hair.

Although people with albinism may experience a variety of eye problems, one of the myths about albinism is that it causes people to have pink or red eyes. In fact, people with albinism can have irises varying from light gray or blue to brown. (The iris is the colored portion of the eye that controls the size of the pupil, the opening that lets light into the eye.) If people with albinism seem to have reddish eyes, it's because light is being reflected from the back of the eye (retina) in much the same way as happens when people are photographed with an electronic flash.

People with albinism may have one or more of the following eye problems:

• They may be very far-sighted or near-sighted, and may have other defects in the curvature of the lens of the eye (astigmatism) that cause images to appear unfocused.
• They may have a constant, involuntary movement of the eyeball called nystagmus.
• They may have problems in coordinating the eyes in fixing and tracking objects (strabismus), which may lead to an appearance of having "crossed eyes" at times. Strabismus may cause some problems with depth perception, especially at close distances.
• They may be very sensitive to light (photophobia) because their irises allow "stray" light to enter their eyes. It's a common misconception that people with albinism shouldn't go out on sunny days, but wearing sunglasses can make it possible to go outside quite comfortably.

In addition to the characteristically light skin and eye problems, people with a rare form of albinism called Hermansky-Pudlak Syndrome (HPS) also have a greater tendency to have bleeding disorders, inflammation of the large bowel (colitis), lung (pulmonary) disease, and kidney (renal) problems.

Diagnosis

It's not always easy to diagnose the exact type of albinism a person has; there are two tests available that can identify only two types of the condition. Recently, a blood test has been developed that can identify carriers of the gene for some types of albinism; a similar test during amniocentesis can diagnose some types of albinism in an unborn child. A chorionic villus sampling test during the fifth week of pregnancy may also reveal some types of albinism.

The specific type of albinism a person has can be determined by taking a good family history and examining the patient and several close relatives.

The "hairbulb pigmentation test" is used to identify carriers by incubating a piece of the person's hair in a solution of tyrosine, a substance in food which the body uses to make melanin. If the hair turns dark, it means the hair is making melanin (a "positive" test); light hair means there is no melanin. This test is the source of the names of two types of albinism: "ty-pos" and "ty-neg."

The tyrosinase test is more precise than the hairbulb pigmentation test. It measures the rate at which hair converts tyrosine into another chemical (DOPA), which is then made into pigment. The hair converts tyrosine with the help of a substance called "tyrosinase." In some types of albinism, tyrosinase doesn't do its job, and melanin production breaks down.

Treatment

There is no treatment that can replace the lack of melanin that causes the symptoms of albinism. Doctors can only treat, not cure, the eye problems that often accompany the lack of skin color. Glasses are usually needed and can be tinted to ease pain from too much sunlight. There is no cure for involuntary eye movements (nystagmus), and treatments for focusing problems (surgery or contact lenses) are not effective in all cases.

Key terms

Amino acids — Natural substances that are the building blocks of protein. The body breaks down the protein in food into amino acids, and then uses these amino acids to create other proteins. The body also changes amino acids into melanin pigment.

Astigmatism — An eye condition in which the lens doesn't focus light evenly on the retina, leading to problems with visual sharpness.

Carrier — A person with one normal gene and one faulty gene, who can pass on a condition to others without actually having symptoms.

DNA — The abbreviation for "deoxyribonucleic acid," the primary carrier of genetic information found in the chromosomes of almost all organisms. The entwined double structure allows the chromosomes to be copied exactly during cell division.

DOPA — The common name for a natural chemical (3, 4-dihydroxyphenylalanine) made by the body during the process of making melanin.

Enzyme — A protein that helps the body convert one chemical substance to another.

Gene — The basic unit of genetic material carried in a particular place on a chromosome. Genes are passed on from parents to child when the sperm and egg unite during conception.

Hairbulb — The root of a strand of hair from which the color develops.

Hermansky-Pudlak Syndrome (HPS) — A rare type of albinism characterized by a problem with blood clotting and a buildup of waxy material in lungs and intestines.

Melanin — Pigment made in the hair, skin and eyes.

Nystagmus — An involuntary back-and-forth movement of the eyes that is often found in albinism.

Strabismus — Crossed or "lazy" eyes, often found in albinism.

Tyrosinase — An enzyme in a pigment cell which helps change tyrosine to DOPA during the process of making melanin.

Tyrosine — A protein building block found in a wide variety of foods that is used by the body to make melanin.

Crossed eyes (strabismus) can be treated during infancy, using eye patches, surgery or medicine injections. Treatment may improve the appearance of the eye, but it can do nothing to cure the underlying condition.

Patients with albinism should avoid excessive exposure to the sun, especially between 10 a.m. and 2 p.m. If exposure can't be avoided, they should use UVA-UVB sunblocks with an SPF of at least 20. Taking beta- carotene may help provide some skin color, although it doesn't protect against sun exposure.

Prognosis

In the United States, people with this condition can expect to have a normal lifespan. People with albinism may experience some social problems because of a lack of understanding on the part of others. When a member of a normally dark-skinned ethnic group has albinism, he or she may face some very complex social challenges.

One of the greatest health hazards for people with albinism is excessive exposure to sun without protection, which could lead to skin cancer. Wearing opaque clothes and sunscreen rated SPF 20, people with albinism can safely work and play outdoors safely even during the summer.

Prevention

Genetic counseling is very important to prevent further occurrences of the conditon.

Perihal Penyakit keturunan ANEMIA SEL SABIT

Apakah Anemia Sel Sabit?

( Autosom kromosom 11)

Penyakit sel sabit adalah sekelompok gangguan pendarahan di mana pasien memiliki hemoglobin yang tidak normal, komponen penting dalam sel darah merah. Pasien dengan kondisi ini tidak memiliki hemoglobin normal tetapi memiliki hemoglobin berbentuk sabit yang menyerupai huruf S.

Haemoglobin  di dalam sel darah merah yang berperan mengangkut molekul oksigen. Setiap sel darah merah dapat menampung beberapa juta hemoglobin. 

Seseorang dikatakan menderita anemia sel sabit ketika kedua gen yang cacat untuk hemoglobin diturunkan dari kedua orang tua. 

Akan tetapi, ketika seseorang hanya menerima salah satu gen yang cacat dari orang tua, orang tersebut dikatakan pembawa sel sabit. Pada orang seperti itu yang memilki beberapa sel sabit dalam aliran darahnya tetapi tidak menderita anemia sel sabit dan gejala-gejalanya.

 Meskipun penyebabnya belum diketahui, seseorang dengan pembawa sel sabit memiliki proteksi lebih tinggi terhadap malaria. Pada penderita anemia sel sabit, bentuk sel darah merah yang abnormal menurunkan kelenturannya. 

 Maka dari itu, sel darah menempel dan menyumbat pembuluh darah, mengurangi asupan oksigen pada jaringan yang berdekatan dan menimbulkan gejala, seperti nyeri sendi, nyeri perut, dan nyeri tulang. Episode-episode nyeri ini dikenal sebagai krisis sel sabit. Hal ini dapat berat pada beberapa anak dan memerlukan perawatan di rumah sakit.

 Penyumbatan pembuluh darah juga dapat meningkatkan potensi kondisi yang mengancam jiwa, seperti stroke. Sel darah yang abnormal tersebut juga mati secara prematur, menyebabkan sel-sel darah merah berumur pendek. Oleh karena itu, penderita anemia sel sabit biasanya mudah lelah dan mudah kehilangan nafas. Meskipun tidak ada penyembuhan untuk kondisi ini, penanganan yang tersedia hanya membantu mengendalikan gejala. Pada kasus berat dimana jumlah sel darah merah sangat rendah, transfusi darah diperlukan.

      Apa itu Penyakit Sel Sabit: Gejala, Penyebab, Diagnosis, & Cara Mengobati

Apa itu Penyakit Sel Sabit?

Penyakit sel sabit adalah sekelompok gangguan pendarahan di mana pasien memiliki hemoglobin yang tidak normal, komponen penting dalam sel darah merah. Pasien dengan kondisi ini tidak memiliki hemoglobin normal tetapi memiliki hemoglobin berbentuk sabit yang menyerupai huruf S.


Penyakit sel sabit adalah penyakit yang paling menonjol di daerah tropis, khususnya di sub-Sahara Afrika, di mana tingkat kasus yang terjadi sebesar 75 persen. Sekitar 150.000 bayi yang baru lahir di Nigeria didiagnosis mengidap penyakit ini setiap tahun. Kondisi serupa juga terjadi di Timur Tengah dan India. Pola migrasi penyakit ini dari daerah tersebut telah meningkat secara signifikan ke negara-negara Eropa. Sementara itu, di Amerika Serikat, kondisi ini terjadi pada sekitar 1 dari setiap 5.000 orang. Di seluruh dunia, sekitar 300.000 anak lahir dengan kondisi ini setiap tahun. Penyakit sel sabit telah menyebabkan lebih dari 175.000 kematian setiap tahun. Namun, sekitar 50% pasien dengan kondisi ini dapat hidup lebih dari 50 tahun.

Penyebab Penyakit Sel Sabit

Penyakit sel sabit merupakan kelainan bawaan, yang berarti bahwa kondisi ini diwariskan dari orang tua ke anak. Penyebabnya adalah mutasi pada gen tertentu, ditemukan pada kromosom 11. Hal ini menyebabkan cacat dalam produksi komponen beta globin pada hemoglobin. Pola pewarisan penyakit ini adalah resesif autosomal.

Mutasi tersebut menghasilkan sel darah merah yang kaku dan meningkatkan kekentalan darah. Pada pasien dengan kondisi ini, elastisitas sel darah merah berkurang, sehingga mencegah sel-sel mendeformasi dengan fleksibel dan melewati pembuluh darah yang kecil. Hal ini menyebabkan terjadinya penyumbatan pada pembuluh darah kecil, menyebabkan buruknya suplai darah dan berkurangnya pengiriman oksigen ke berbagai organ, dan kemudian menyebabkan gejala sel sabit. Selain itu, penyakit sel sabit juga meyebabkan hancurnya sel darah merah, yang dikenal sebagai hemolisis. Meskipun tubuh menciptakan sel-sel darah baru untuk menggantikan yang rusak, tubuh tidak dapat mengejar laju kerusakan sel darah, sehingga terjadi anemia.

Gejala Utama Penyakit Sel Sabit

Penyakit sel sabit sudah ada sejak seorang lahir. Akan tetapi, penyakit ini biasanya tidak terlihat sampai sekitar usia lima bulan. 

Pemeriksaan darah merupakan hal yang wajib di Amerika Serikat, bahkan orang tua diberitahu sebelum gejala apapun muncul pada anak.

Penampakan awal dari kondisi ini termasuk pembengkakan pada kaki dan tangan yang disertai nyeri. Pasien juga tampak pucat, mudah lelah, dan lesu; kondisi yang dapat dikaitkan dengan anemia. Beberapa pasien mengalami menguningnya kulit, kondisi yang dikenal sebagai penyakit kuning yang disebabkan oleh penghancuran sejumlah besar sel darah merah. Rasa sakit yang terus-menerus juga umum terjadi, terutama di kalangan remaja dan orang dewasa. Limpa juga biasanya terpengaruh; kerusakan organ ini membuat pasien rentan terhadap infeksi menular. Borok atau bisul pada kaki juga mungkin terjadi pada pasien dan kondisi ini dapat berulang atau tidak dapat sembuh sebagaimana mestinya.
Beberapa pasien dengan penyakit sel sabit menampakkan gejala komplikasi seperti nyeri tajam secara tiba-tiba. Hal ini disebabkan oleh penyumbatan aliran darah di pembuluh darah. Nyeri bisa dirasakan di mana saja, tetapi umumnya dirasakan di punggung bagian bawah serta kaki dan tangan. Nekrosis tulang juga dapat terjadi, dan pasien biasanya mengalami rasa sakit dan kesulitan dalam berambulasi. Penyumbatan ini mungkin dipicu oleh beberapa kondisi, termasuk kesakitan, dehidrasi dan stres.
Pasien juga dapat menderita stroke, di mana aliran darah ke otak tersumbat. Hal ini menimbulkan gejala lemahnya salah satu sisi tubuh, kesulitan berbicara, kehilangan keseimbangan atau bahkan tanda-tanda ringan disfungsi kognitif. 10 sampai 20% dari pasien dengan penyakit sel sabit dapat menderita stroke pada usia 45 tahun.
Salah satu komplikasi yang paling ditakuti dari kondisi ini adalah sindrom akut pada dada, di mana pasien mengalami demam, nyeri dada, kesulitan bernapas dan tingkat oksigen yang rendah. Sekitar seperempat dari semua kasus kematian akibat penyakit sel sabit disebabkan oleh komplikasi ini.

Siapa yang Perlu Ditemui dan Jenis Pengobatan yang Tersedia

Penyakit sel sabit pada dasarnya paling baik ditangani oleh seorang hematolog, seorang dokter yang terlatih dalam pengelolaan kelainan darah. Diagnosis dini sangat penting untuk mencegah perkembangan komplikasi. Tindak lanjut reguler setiap 3-12 bulan disarankan.

Tes darah biasanya dilakukan untuk memeriksa anemia. Imunisasi rutin juga harus diberikan untuk mencegah perkembangan infeksi. Selain vaksin rutin untuk anak-anak, pasien berpenyakit sel sabit juga dapat menerima vaksin influenza biasa, pneumokokus dan meningokokus.

Obat untuk rasa sakit dapat diberikan untuk meringankan rasa sakit, akan tetapi beberapa komplikasi mungkin memerlukan rawat inap.

 Anemia parah mungkin memerlukan transfusi darah berulang sementara stroke membutuhkan penanganan yang tanggap dan pemantauan ketat di rumah sakit.

 Pasien yang mengalami sindrom akut pada dada juga harus segera dibawa ke rumah sakit sehingga mereka dapat dengan segera diberikan antibiotik dan terapi suportif menggunakan oksigen.

Hidroksiurea (HU) adalah obat yang telah terbukti berguna untuk pengobatan pasien dengan penyakit sel sabit. Penelitian telah menunjukkan bahwa HU menyebabkan berkurangnya kesakitan, kebutuhan transfusi, nyeri, dan resiko yang lebih rendah untuk pengembangan sindrom akut pada dada.
Satu-satunya pengobatan yang telah terbukti efektif pada penyakit sel sabit adalah transplantasi sumsum tulang.