Biology

French geneticist Jerome Lejeune is the person who discovered Cri-du-Chat syndrome in 1963. He is also the one who discovered the genetic basis of Down syndrome. Lejeune observed that babies born with this particular syndrome exhibit a distinctive monotonous, high-pitched cry resembling that of a cat’s. He named the disorder as “Cri-du-Chat”, the French for “cry of the cat.” It is estimated that 1 in 25,000 births has Cri-du-chat syndrome worldwide.

Babies born with Cri-du-Chat syndrome have structural abnormalities to their larynx which is the reason why their cry resembles that of a cat’s. Besides from the problem with the larynx there are other abnormalities observed in children with Cri-du-chat syndrome which include the following:

• Low birth weight
• Small head (Microcephaly)
• Small, receding chin (Micrognathia)
• Round face
• Widely spaced eyes (Hypertelorism)
• Fold of skin over the eyes
• Epicanthic folds
• Creases on the palms
• Short fingers
• Flat nasal bridge
• Mental retardation, aggression, hyperactivity

• Heart defects (e.g. ventricular septal defect)
• Cleft palate
• Scoliosis
• Hernias
• Bowel abnormalities
• Kidney diseases (e.g. hydronephrosis, renal ectopia, horseshoe kidneys)
• Hearing impairments
• Gastrointestinal diseases
• Frequent ear infections
• Low muscle tone

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Genetics of Cri-du-Chat Syndrome

Cri-du-Chat syndrome is caused by a break in the small arm of chromosome 5. Several genes are lost as a result of the breakage which occur during the development of sperm (spermatogenesis) or egg (oogenesis). If a sperm with the defect fertilizes a normal egg, the child will develop Cri-du-Chat syndrome. And if the egg has the defect while the sperm is normal, the child will develop the disorder. Take note that not all the sperms or eggs have the chromosomal break so parents who have a child with the disorder can still produce normal children. By chance, a child can inherit a broken chromosome if one of his/her parents has Cri-du-Chat syndrome.[ad#afterpost]

Ocular albinism is an inherited genetic disorder in which the eyes lack melanin, the substance that gives pigmentation to the irises (colored part of the eye), skin, and hair. Unlike a person with oculocutaneous albinism, a person with ocular albinism has skin and hair that show normal or near-normal coloration. Eye pigmentation is important for normal vision.

The most common form of ocular albinism is the Nettleship-Falls type or ocular albinism type 1. There are other forms of ocular albinism but they are much rarer and may be associated with additional symptoms, like hearing loss.

Symptoms for Ocular Albinism

The main symptom of ocular albinism is the complete or partial absence of pigmentation in the iris and the retina, the light sensitive membrane in the back of the eye. The color of the eye iris can vary from blue to green or even brown, and sometimes darken with age. When a doctor examines the eye of an affected individual by shining light from the side of his/her eye, the light shines back through the iris because very little melanin pigment is present.

Other symptoms for ocular albinism include rapid, involuntary movements of the eye (nystagmus), increased sensitivity to light (photophobia), eyes that are not aligned in parallel or do not see in the same direction (strabismus), stereoscopic vision or problems with combining vision from both eyes to perceive depth, and severely impaired sharpness of vision (visual acuity).

The pattern of routing of nerves from the back of the eye to the brain in an individual with ocular albinism is different from that of a normal person. This creates a problem in vision and in the way the eyes function.

With regards to skin color, an individual with ocular albinism may have lighter skin tone than other members of his/her family but this difference is usually negligible.

Treatment for Ocular Albinism

For treatments of ocular albinism, read the article on cures for albinism.

Prevalence of Ocular Albinism

According to a statistics from NIH, at least 1 in 60,000 males suffer from ocular albinism. The condition is more common in males than in females.[ad#co-1]

What Causes Ocular Albinism – The Genetics of Ocular Albinism

Ocular albinism type 1 is caused by a mutation in the GPR143 gene. This gene provides the instruction for the production of protein that plays a role in skin and eye pigmentation. The protein helps control the growth of melanosomes, which are cellular structures that manufacture and store the pigment melanin. Melanin gives color to eyes, hair, and skin. It is also found in the retina and plays a role in normal vision.

How Ocular Albinism is Inherited?

The GPR143 gene is located in X chromosome, a sex chromosome found in both males and females. Females carry two X chromosomes while males carry only one (the other is Y chromosome). Since the gene is located in the X chromosome, ocular albinism type 1 is inherited in an X-linked pattern.

Males develop ocular albinism just by inheriting an X chromosome with the mutated gene from their mothers. Females on the other hand, should inherit two X chromosomes with the mutated GPR143 gene from their fathers and mother in order to develop ocular albinism.

If a female only inherited one affected X chromosome, she may not develop ocular albinism but she is considered a carrier of the defective gene. She can pass it to her children. All her male children develop ocular albinism because they only have one X chromosome. The female children will develop ocular albinism if their father also carries the mutated gene in his X chromosome. In other words, females develop ocular albinism if both of their parents carry the mutated GPR143 gene. This is the reason why ocular albinism is less common in females than in males.

Carrier females or those who carry only one X chromosome with the mutated form of GPR143 do not experience vision loss or other significant eye abnormalities but they may have mild changes in retinal pigmentation that can be detected during an eye examination.[ad#afterpost]

Reference

Ocular Albinism – Genetics Home Reference

Introduction

In popular culture, albinism has been portrayed negatively resulting to the reinforcement of societal prejudice and discrimination against albinistic people. Albino people have been represented in films, books, comics, and other works as people with danger, terror, or criminality. They have also been the object of jokes and ridicule and have been described as evil, maladjusted, under socialized, and freaks. Fictional characters in movies and books with albinistic characteristics (pale skin, platinum blonde hair, blue-red eyes, etc.) appear as the villains most of the time. In fact, a total of 68 films depicting “evil albino” has been made from 1960-2006, according to the National Organization for Albinism and Hypopigmentation. Popular movies such as the Da Vinci Code and The Matrix Reloaded have albinistic characters that appear as evil villains.

In real life, albinistic people are not only socially persecuted because of their traits but also physically abused because of folklore, legends, and myths. In Zimbabwe, modern folklore posits that HIV can be treated by having sexual intercourse with an albinistic person. As a result, albinistic women are raped and subsequently infected with the viral disease. In another African country, Tanzania, albinistic people are hunted and killed for their highly priced body parts. Witchdoctors buy limbs, blood, genitals, hair, skin, organs, and other body parts of an albinistic person; they will use this body parts to make potions and concoctions that promise wealth and good luck to any person who will consume them.

Even if albinistic people are socially ridiculed as maladjusted and under socialized people, there are some of them who have gained fame because of showcasing their talents to the public. They are also actively involved in educating the public about the right way of looking at albinism. Below is the list of famous people with albinism.

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Famous Albino People in Films and Television

• Michael Bowman – American actor starred in Me, Myself & Irene
• Dennis Hurley – American movie producer, actor, writer, comedian, and singer
• Victor Varnado – African-American stand-up comedian and actor
• Redford White – Filipino actor and comedian
• Darnell Swallow – Contestant of Big Brother 9 UK in 2008

Famous Albino in Fashion Modeling

• Shaun Ross – First male albinistic model in mainstream fashion industry and appeared in various periodicals
• Connie Chiu – First female albinistic model in mainstream fashion industry

Famous Albino People in Music

• Cano Estremera – Puerto Rican salsa musician
• Winston Foster – a.k.a. “King Yellowman” is a Jamaican dancehall musician
• G. Harishankar – Carnatic khanjira drummer
• Krondon – American rapper and hip hop musician
• Salif Keita – popular Malian musician
• Malford Milligan – American blues and soul singer
• Corrie Moodie – a.k.a. “Prince Yellowman” is a Jamaican dancehall musician currently living in Canada
• Mem Nahadr – African-American performance artist, composer, and jazz vocalist
• Ali Newman – a.k.a. “Brother Ali” is a hip hop artist from Minneapolis, Minnesota
• Hermeto Pascoal – Jazz musician from Brazil
• Willie Perryman – American blues musician
• David Wrench – Welsh-born electronic musician
• Edgar and Johnny Winter – American blues-rock musician brothers
• Levan Wee – Lead singer of Ronin, a Singaporean band

Other Famous People with Albinism

• Stanley Kaoni – Former militant leader  in Solomon Islands; has OCA1b type of albinism
• Zephanie Kameeta – Namibian religious and political leader
• William  Archibald Spooner – Anglican priest
• Seinei – Fifth century Emperor of Japan
• Zal – Warrior of Ancient Persia (present day Iran); zaal is the Persian term for albinistic people

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References

Famous People with Albinism – Cambridge Encyclopedia

Famous People with Albinism – Wikipedia

Albinism is medically called hypopigmentary congenital disorder but it is also called by other names such as achromatosis, achromia, or achromasia. Albinism results from the complete or partial absence of the pigment melanin that provides color to skin, hair, and the eyes. People with albinism are called albinos; albino animals (e.g. snakes, birds) are also found in nature. Albinos have extremely light skin and hair (yellow or red tinge); they can also have hazel, blue, or brown eyes.

Albinism is derived from the Latin word albus which means white. Albinism is a genetic disease affecting the enzyme tyrosinase involved in the production of melanin. There are two different forms of albinism: hypomelanism/hypomelanosis and amelanism/amelanosis. Hypomelanism is the partial lack of melanin while amelanism is the complete absence of the pigment.

Albinism has been recognized in earlier times, in different cultures.  The condition is mentioned in the writings of early Roman scholars such as Plinius Secundus and Aulus Gellius. Although these scholars described the condition, they did not recognize albinism as a disease.

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It was the English physician Sir Archibald Garrod (1857-1936) who first recognized albinism as a disease some time in 1908. According to him, albinism is a kind of hereditary inborn error of metabolism. Sir Garrod conducted extensive research on albinism. He observed that albino people have hypersensitivity to light, eye misalignment (strabismus), astigmatism, nystagmus, abnormal decussation or crossing of the optic nerves, underdevelopment of the optic nerve and retina.

Although the biological cause of albinism is already known, there are still societies that are not well educated about the disease. Albino people are widely discriminated because of their physical differences to the rest of the population especially in Africa where a majority of the population . Do you that albino people are hunted and killed in Tanzania? There is a black market of albino body parts in Tanzania. Limbs, eyes, skin, hair, tongue, genitals, and organs of albino people are sold to witchdoctors in Tanzania. Witchdoctors use the body parts to make potions that promises wealth and good fortune to those who will drink the “magical potions.”[ad#afterpost]

From the smallest virus to the largest oak tree in the planet, enzymes are found. Enzymes are special type of protein that acts as organic catalysts for accelerating the rate of biochemical reactions in living organisms. There are many enzymes found in an organism and each of these enzymes has specific function. There are enzymes that work for food digestion, DNA replication, energy production, protein synthesis, and among other anabolic and catabolic biochemical reactions. Life on earth is impossible without enzymes.

Do you have any idea on how do enzymes work to accelerate biological reactions?  A typical reaction carried out by an enzyme is 100 million times faster than a reaction that didn’t use enzyme. Without enzymes that act as organic catalysts, biological reactions can even be described as “non-existent” because of very slow reaction.

An example of enzyme is rennin. The function of rennin is to coagulate milk (milk curdling) in the stomach of young mammals. Milk curdling is necessary for the milk to stay longer in the stomach for proper digestion. Without rennin, milk easily passes through the stomach and intestines undigested and unabsorbed by the body. Rennin is important for the survival of mammals after birth since milk is their primary food.

This page would not be enough if we are going to write all the enzymes already identified by scientists. It is not necessary to familiarize ourselves with their names but it is very important to learn and understand how enzymes work in biological reactions.
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How Do Enzymes Work?

Each enzyme is translated into protein (by ribosomes) using the instruction provided by the genes. Each enzyme is encoded by only one gene. In terms of structure, enzymes differ from each other since they are encoded by different genes. However, enzymes are similar in one aspect: they all have active sites in their structures. It is in the active site where the substrate (the molecule to be modified) binds to form a complex: the enzyme-substrate complex. After successful binding, a biochemical reaction takes place and the substrate is transformed to different molecule(s) called the product(s). The catalytic reaction ends when the products are released, but take note that the enzyme remains unchanged after the reaction. The enzyme can bind to another substrate again and the reaction continues.

Although we already know how an enzyme and substrate reacts with each other, it is not yet clear why an enzyme is “specific” or able to recognize only one kind of substrate. There are two theories proposed by scientists to explain the specificity of enzymes: the lock and key hypothesis and induced-fit hypothesis.

Theories on How Do Enzymes Work – Enzyme Specificity

Lock and Key Hypothesis – This hypothesis states that the enzyme and substrate are complementary to each other in terms of shape. The shape of the substrate fits to the shape of the enzyme’s active site to form the enzyme-substrate complex. Only substrates that can fit to the active site will be acted upon by the enzyme. The substrate acts like a “key” why the active site acts like a “lock”.

Induced Fit Hypothesis – This hypothesis states that the substrate modifies its structure as it binds to the active site in order to provide an exact position for the enzyme to act upon. In some instances, the active site modifies itself to accommodate the substrate. This is observed in glycosidase enzymes.

Diseases Associated to Enzymes

There are many human diseases that are caused by deficiency or imbalance of enzymes. Among these diseases include diabetes, phenylketonuria, albinism, cystic fibrosis,  MTHFR deficiency, and many more. Some diseases associated to enzymes are caused by genetic mutation. Mutated genes encode for defective enzymes that are unable to catalyze biological reactions.[ad#afterpost]