Article A: Albinism
Reader:___________________
What causes albinism?
Albinos around the world face day-to-day health issues, but in Africa they have a bigger problem: being hacked
to death for body parts
February 18, 2009 |By Coco Ballantyne
Albinos—people with white hair and skin, and often reddish eyes
—are being mutilated and murdered for their body parts in
Tanzania, according to The New York Times. Sometimes as family
members look on in horror, groups of machete-wielding men have
chopped off the legs, heads, and genitals of albinos.
Among the dead: a seven-month-old baby, a cassava farmer with
two children, and a child murdered by his own father, according
to reports by the BBC. The brutal killings -- 40 since 2007 -- are
fueled by rumors that albino blood, skin, and hair have magical
powers. People are actually weaving albino hair into their fishing
nets and fashioning amulets with albino body parts, hoping that
these devices will bring them riches, The Times reports in a story
profiling Canadian albino Peter Ash, founder of Under the Same
Sun, an albinism advocacy organization aimed at shaming the
Tanzanian government into stopping the murders.
©iStockphoto.com/ManoAfrica
The horrifying scenes pile onto the day-to-day issues albinos face: Albinism is a debilitating
condition that causes vision loss, extreme sun-sensitivity, and sometimes embarrassment and
stigma. Albinos have long been villainized in literature and pop culture—think Silas, the evil monk
in The Da Vinci Code, or the nefarious blond twinsin The Matrix Reloaded.
So what causes albinism, and are there any treatments? To find out, we checked in with Raymond
Boissy, a professor of dermatology at the University of Cincinnati College of Medicine.
[An edited transcript of the interview follows.]
What is albinism?
Albinism is a disease in which a person has partial or complete loss of pigmentation (coloring) of
the skin, eyes and hair.
What causes it?
Genetic mutations that affect the production of a pigment called melanin. There is a cell called the
melanocyte that is responsible for giving skin, hair, and eyes pigmentation. In albinism, the
melanocytes are present, but genetic mutations interfere with their pigment production or their
ability to distribute it to keratinocytes, the major cell type comprising the epidermis, or outer layer of
the skin. There are currently five known genetic types of albinism, the most common being
oculocutaneous type 1 (OCA1) and type 2 (OCA2). Oculocutaneous means affecting the eyes and skin
("oculo" meaning eye and "cutaneous" meaning skin).
Patients with OCA1 have mutations in a gene called TYR that is responsible for creating the enzyme
tyrosinase, used by cells to convert the amino acid tyrosine into pigment molecules that color the
skin, hair, and eyes. OCA2, the most common form of albinism in Africa, results from a mutation in
the OCA2 gene, which encodes the P protein. We don't know what this P protein does.
What does a person with albinism look like?
Most people with OCA1 have snow-white skin, snow-white hair, and no pigment in their eyes. The
iris (colored part of the eye that encircles the pupil) is a pale bluish pinkish color, while the pupil may
actually be red. This redness comes from light entering the pupil and reflecting off of blood vessels in
the retina, the light-sensitive layer of tissue lining the back of the eyeball. Normally, the pupil
appears black because pigment molecules in the retina absorb light entering the eye, preventing it
from bouncing back to the outside world.
Those with OCA2 can make a small amount of pigment and thus may have light blond to brown hair
color. Their irises are blue to light gray and their pupils dark red to light gray.
How does this lack of pigment in the eyes affect vision?
People with albinism are legally blind because photoreceptors (cells in the retina that detect light) get
oversaturated with light and send confusing messages to the brain. If you look at a person with
albinism, you'll see a nystagmus, or fluttering, in their eyes; the eyes are sort of bouncing in their
sockets because they are getting a confusing visual stimulus.
What are some other conditions associated with albinism?
Without pigment in the skin, you are more susceptible to non-melanoma skin cancers in
keratinocytes. Normally, melanocytes distribute pigment molecules to keratinocytes, where they act
sort of like umbrellas shielding the nucleus (and the DNA inside) from the sun's UV radiation.
Albinos are particularly at risk for squamous cell carcinoma, a cancer of the outermost layer of skin,
and basal cell carcinomaaffecting deeper layers. They also may experience premature skin aging.
Melanin helps prevents wrinkles and elastosis (breakdown of elasticity) by blocking UV radiation.
Are there any treatments for albinism?
No, there are not. Patients with albinism are advised to protect themselves from the sun.
Are there any treatments in the pipeline?
Some researchers, such as Richard King at the University of Minnesota, are trying to develop gene
therapies, or drugs that would go into the cells and correct DNA mutations responsible for albinism.
So far, scientists have had some success in correcting patches of depigmented skin and hair in mice,
but they are a long way from translating this research to humans.
What animals, besides humans, can be albinos?
Any animal that has melanocytes can get albinism. That means virtually all mammals. Reptiles,
amphibians and lower vertebrates can also be albinos, but these organisms may also have other types
pigment production cells besides melanocytes, so they may not appear colorless. In the zoo here in
Cincinnati, we had an albino alligator.
According to the National Organization of Albinism and Hypopigmentation (NOAH),
one in every 17,000 people in the U.S. has some type of albinism, but the incidence is
much higher in East Africa (about 1 in 3000, according to some estimates). Why this
disparity?
The mutation in OCA2, which is responsible for most albinism cases in Africa, is probably the oldest
mutation causing albinism and, putatively, originated duringmankind's development in Africa. For
some reason, it's retained there.
Article B: Hemophilia
Reader:___________________
What Is Hemophilia?
Hemophilia (heem-o-FILL-ee-ah) is a rare bleeding disorder in which the blood doesn't clot
normally. If you have hemophilia, you may bleed for a longer time than others after an
injury. You also may bleed inside your body (internally), especially in your knees, ankles,
and elbows. This bleeding can damage your organs and tissues and may be life threatening.
Overview
Hemophilia usually is inherited. "Inherited” means that the disorder is passed from parents
to children through genes. People born with hemophilia have little or no clotting factor.
Clotting factor is a protein needed for normal blood clotting. There are several types of
clotting factors. These proteins work with platelets (PLATE-lets) to help the blood clot.
Platelets are small blood cell fragments that form in the bone marrow—a sponge-like tissue
in the bones. Platelets play a major role in blood clotting. When blood vessels are injured,
clotting factors help platelets stick together to plug cuts and breaks on the vessels and stop
bleeding.
The two main types of hemophilia are A and B. If you have hemophilia A, you're missing or
have low levels of clotting factor VIII (8). About 8 out of 10 people who have hemophilia
have type A. If you have hemophilia B, you're missing or have low levels of clotting factor
IX (9).
Outlook
Hemophilia can be mild, moderate, or severe, depending on how much clotting factor is in
your blood. About 7 out of 10 people who have hemophilia A have the severe form of the
disorder. Hemophilia usually occurs in males (with rare exceptions). About 1 in 5,000 males
are born with hemophilia each year.
Case Closed: Famous Royals Suffered
From Hemophilia
By
8 October 2009 (All day)
Queen Victoria's male descendants were cursed with poor health. The 19th century British monarch's son
Leopold, Duke of Albany, died from blood loss after he slipped and fell. Her grandson Friedrich bled out at age
2; her grandsons Leopold and Maurice, at ages 32 and 23, respectively. The affliction, commonly known as the
"Royal disease," spread as Victoria's heirs married into royal families across Europe, decimating the thrones of
Britain, Germany, Russia, and Spain. Based on the symptoms, modern researchers concluded that the royals
suffered from hemophilia--a genetic disease that prevents blood from clotting--but there was never any
concrete evidence. Now, new DNA analysis on the bones of the last Russian royal family, the Romanovs,
indicates the Royal disease was indeed hemophilia, a rare subtype known as hemophilia B.
Hemophilia prevents proteins known as fibrins from forming a scab over a cut or forming clots to stop internal
bleeding. Even minor injuries can lead to bleeding, which lasts for days or weeks and can be fatal. The disease
is recessive and is carried on the X chromosome, meaning that men are more likely to develop it, whereas
women usually act as carriers and don't show symptoms.
Such was the case with Prince Alexei Romanov, son of Tsar Nicholas II, great-grandson of Queen Victoria, and
heir to the Russian throne. From an early age, Alexei was prone to prolonged bleeding, and his family feared
that he wouldn't make it through his first month of life, says Evgeny Rogaev, a geneticist at the University of
Massachusetts Medical School in Worcester. The disease didn't kill Alexei, however: He was murdered at age
13 in 1918 along with the rest of the Russian royal family following the Russian Revolution. Earlier this year,
Rogaev and his colleagues reported that, based on DNA analysis, the bodies of two children found near the
murder site were indeed those of Alexei and his sister Maria. They further confirmed that the other bodies near
the site belonged to the rest of the Romanov family. But Rogaev wanted to solve the final Romanov riddle: Did
they really suffer from hemophilia?
He and colleagues analyzed DNA from the royal bone fragments again, this time looking for genetic markers of
hemophilia. The most common type of the disease, hemophilia A, accounts for about 80% of hemophilia cases
and is caused by a mutation to a gene calledF8, which encodes a protein involved in blood clotting. They didn't
find the mutation. So Rogaev moved on to looking for a rarer form of the disease, hemophilia B, which involves
another gene, F9. This time, the team found a mutation in F9, which would have inhibited clotting, in bones
from Alexei, his sister Anastasia, and their mother Alexandra.
The findings, published online today in Science, indicate that Alexei did indeed have hemophilia B and that his
mother and Anastasia were carriers for the disease, bearing out the previous speculation. They also confirm
that the other instances of "Royal disease" in the family line were hemophilia, Rogaev says, because they all
shared a common genetic heritage. The last carrier of the disease in the royal family was Prince Waldemar of
Prussia, who died in 1945.
The disease impacted not only the Romanov family but also probably Russian history, Rogaev adds. Alexei's
frail condition encouraged his mother Alexandra to keep close company with the Russian mystic Grigori
Rasputin, who claimed to wield healing magic. "There was no medication at that time," Rogaev says. "She tried
to do everything possible." According to some historians, when Rasputin used his close relationship with the
Romanovs to influence bureaucratic affairs in his favor, the public grew increasingly suspicious of the regime,
possibly hastening the revolution.
Katherine High, a hematologist who studies blood coagulation at The Children's Hospital of Philadelphia, says
that the mutation found in the Romanov bones fits an established genetic pattern known to cause hemophilia B,
further supporting Rogaev's findings. Tracing this pattern back to the royal family and its history of disease is
"very interesting and very exciting," she says. As pediatric hematologist Paul Monahan of the University of
North Carolina, Chapel Hill says, "Now it's clear it's had an enormous impact on Western history."
Article C: Height
Reader:__________________
Hey, why do some people get a lot taller than their parents? And why am I a
natural athlete and my parents are totally different? My hair is kinda the same as
theirs but my eyes are way different. Please explain.
-A middle school student from Tennessee
March 9, 2005
We often hear that a child is the "spitting image" of one of
their parents. An identical carbon copy, a couple decades
younger.
How is it then that some of us end up being so different
from our parents? The way we look, our interests, and our
abilities just don't seem to reflect them at all.
There is no single explanation for the differences we see
between generations. Several factors play a part.
Genes have a starring role in determining our physical
attributes. For instance, a single gene decides if we can roll
our tongue into a tube. Two genes determine our base eye
color as brown, blue, or green.
People come in all shapes and sizes
Unfortunately, the genetics governing most of our traits is not nearly as simple. Nor as well
understood. This is because most traits utilize not just one or two genes, but many genes,
to make us the way we are.
When lots of genes are at work, as with height and skin color, we see an entire spectrum of
the trait across the population. For example, there aren't just tall people and short people.
There are people of all heights falling anywhere between tall and short.
Figuring out which genes are responsible for these "many-gene"
traits is challenging. Scientists have identified a few genes that
are thought to be involved in our height. Although the exact
number is not known, they estimate that as few as 7 to more
than 20 genes may be working together on our stature. With so
many players in the "height game", it is no wonder we vary so
much from one another.
This explains why we may not stand eye to eye with our friends.
But what about the differences we see in our own families?
As you mentioned, some children are considerably taller than their
parents. Basketball legend, Wilt Chamberlain, was a towering 7'1".
Strangely, neither of his parents stood above 5'9". Of course, children can be much shorter
than their parents, too. So how do a bunch of genes work together to determine our height?
Let's say, for the sake of simplicity, only three genes control our height. We will call
them A, B, and C. An uppercase letter, like A, means "tall". A lowercase letter, likea, means
"short".
Remember that we have two copies of every gene, one from
dad and one from mom. Keeping that in mind, we would have
6 copies of these 3 genes. Our final height is then an average
of the number of "tall" and "short" copies we inherit.
For an example, let's take a father whose gene makeup is
AaBbCc and a mother with aaBBCc. With 3 "tall" and 3 "short"
copies each, both are of average height. How tall will their kids
grow?
Which copy of each gene we inherit from our parents is random.
In this family, the children will most likely inherit 3 "tall" and 3
"short" copies. Like their parents, they will be average height.
But this will not always be the case.
There is a smaller chance that their child could inherit five "tall" copies, ABC from dad
and aBC from mom. This child will be quite tall. On the other hand, dad could pass
down abc and mom could pass down aBc. With five "short" copies, this child would be
considerably shorter. Imagine how many possibilities there would be if twenty genes
controlled our height!
All the burden of our stature cannot be placed solely on our genes. Many factors contribute
to our final adult height. These are called Environmental Effects. They act on our "genetic
height" to make us taller or shorter. Some of these factors are at work very early, before we
are even born! A mother's health while she is pregnant is thought to be a key player. Poor
diet and toxic substances, like alcohol and nicotine, can be harmful to the growth of her
child.
After we are born, healthy eating habits are vital in reaching our maximum height. Avoiding
drugs, environmental pollutants, and childhood illnesses is important. As is getting enough
exercise and sleep. Many of our traits follow a similar pattern. They are a blending of lots of
different genes as well as our environment.
Is this also true regarding how athletic we are? Sure. As we just talked about, our genes are
important in designing our bodies. Height is important for success in sports like basketball
and gymnastics. Endurance and lean muscles are critical to a long distance runner.
But even at seven feet tall, you may not excel at basketball. Many things can affect how
successful we are at different activities. Do we enjoy the activity? Are there local teams or
clubs that we can join to help us practice? As the old adage says, practice makes perfect!
Do we have strong interests in other areas, like music or art, which limit our time? Can we
afford to do the activity? Downhill skiing, photography, and painting are expensive hobbies.
There are many reasons that we are the way we are. Our genes make a significant
contribution. But our lifestyle is important, too!
Article D: Sickle Cell Disease
Reader:__________________
Sickle Cell Disease
Sickle cell disease is a serious blood disorder that causes acute pain, severe anemia, infections, and
vascular blockages that can lead to widespread organ damage and death. It is a genetic disease, the
most common inherited blood disorder in the United States, where it occurs most often in AfricanAmericans and Hispanics. Until the past few decades, most people with SCD did not live beyond young
adulthood, but advances in treatment have improved and lengthened the lives of patients who have
access to good medical care.
SCD affects millions of people worldwide, particularly those with African, Spanish, Mediterranean, and
Indian ancestry. Some 120,000 infants are born with SCD every year worldwide. In the United States,
approximately 1 in 500 African-Americans and 1 in 1,200 Hispanic Americans are born with SCD. Some 2
million Americans—including about 10 percent of the African-American population—carry one gene for
SCD, the "sickle cell trait."
While bone marrow/stem cell transplantation appears to have successfully cured a small number of SCD
patients, the vast majority of people with SCD are not candidates for this costly and high-risk procedure,
meaning that there is not yet a common cure for the disease.
The oxygen that we need to live is taken from the lungs to the rest of the body by red blood cells. A
protein in the blood called hemoglobin carries the oxygen. In sickle cell disease, hemoglobin molecules
stick to one another, distorting the shape of the blood cells.
Causes
Sickle cell disease is a group of inherited disorders caused by a defect
in hemoglobin, the protein in red blood cells that transports oxygen
from the lungs to the rest of the body and carries carbon dioxide back
to the lungs.
Most people with SCD have a single defect on both copies of chromosome 11 that causes them to
produce defective hemoglobin molecules, which bind together and form long, rod-like structures
(polymers) when not carrying oxygen. This causes the red blood cells to become rigid and misshapen.
While normal red blood cells are pliable, smooth, disk-shaped, and live for approximately 120 days in the
bloodstream, red blood cells in SCD patients may have the shape of a crescent, or sickle, and typically
survive for only about 10 to 20 days. Because of the abnormal cells' abbreviated life span, the body
cannot replace them quickly enough, causing the blood to be chronically short of red blood cells, a
condition called anemia.
These cells' distorted shape (and numerous other abnormalities) can prevent them from traveling through
small blood vessels, causing them to accumulate and create blockages that deprive organs and tissues of
oxygenated blood. Because this often painful process—known as vaso-occlusion—can damage tissue
and vital organs, it can lead to life-threatening complications.
Some people with SCD have two different mutations, one on each copy of chromosome 11; in some of
those cases, the disease can be slightly less severe than the most common form of SCD.
Risk factors
Sickle cell disease is inherited and can occur only when both parents carry the sickle cell trait. While
children of any race can be born with the condition, in the United States it is most prevalent among
African-Americans and second-most common among people of Hispanic origin. Worldwide, sickle cell
disease occurs most frequently in people whose ancestry originated in regions that include:
 Sub-Saharan Africa. (In some parts of Africa, as many as 2 percent of babies are born with SCD, and
up to 25 percent of the people are believed to carry the sickle cell trait.)
 Spanish-speaking regions of Central America, South America, and parts of the Caribbean
 Saudi Arabia
 India
 Sri Lanka
 Mediterranean countries such as Turkey, Greece, and Italy
Sickle cell trait
Understanding who gets sickle cell disease calls for a brief genetics lesson.
Children typically inherit one copy of the normal hemoglobin beta chain gene (hemoglobin A) from each
parent. But some children instead inherit one or two mutated hemoglobin genes—usually genes known
as hemoglobin S, C, D, E, or O.
Those who inherit a hemoglobin A gene from one parent and a hemoglobin S gene ("the sickle cell gene")
from the other parent have what is known as sickle cell trait (AS), a condition in which red blood cells
contain both hemoglobin A and hemoglobin S. The red blood cells of people with sickle cell trait usually
contain slightly more hemoglobin A than S.
Sickle cell trait is a genetic state, not a disease, and it cannot develop into SCD. Having the sickle cell
trait does, however, increase the odds of producing a child with two copies of the hemoglobin S gene,
who therefore who has sickle cell disease.
• When both parents possess the sickle cell trait, each pregnancy has the following odds:
 25 percent chance of producing a child with sickle cell disease (SS)
 25 percent chance of producing a child with neither sickle cell trait nor sickle cell disease
 50 percent chance of producing a child with sickle cell trait
• When one parent has SCD and the other has the sickle cell trait, each pregnancy has a 50 percent
chance of producing a child who has either the sickle cell trait or sickle cell disease.
While most people with the sickle cell trait are unaffected carriers who don't experience SCD symptoms
or complications, a very small number can develop problems when they are exposed to factors such as:
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High altitude
Increased atmospheric pressure
Low oxygen
Severe dehydration
Last reviewed on 1/28/10