Sickle Cell Anemia and Blacks/African-Am.

[Arimas]

Today, I had blood results for my annual check up with this new doctor. He told everything was normal and that my (...?) is AA which means I don't have Sickle Cell anemia. I didn't get what he meant the first time and thought he was talking about my blood type...I was ready to say no I am A...

I have never heard of a disease like that but remember reading somewhere in this MB the word "sickle cell" without paying much attention to it.

Now, I have googled and found some info...it is a disease that is more frequent with Africans or people of Black ancestry. But I was wondering if there is a part of Africa where it happens more because I don't think people share the same medical conditions and pre-disposition to the same illnesses all over Africa.


A

[Arimas]

I just found what I was looking for and could share the info. If anyone is interested to know more about the sickle cell map, I have one paper and an interesting website.

[cacio]

Arimas:

is sickle cell anemia one of those diseases where, if you have the mutation in one chromosome, you're protected from malaria, but, if you have two, you get the disease? It would be nice to see a map.

Italy had some malaria too in the past, so I know that some of these diseases are present in Southern Italy (eg Sardinia), though I don't think it's sickle cell anemia. (I heard of a disease called thalassemia).

cacio

[GregKiroKHR1bL1]

Sickle Cell Disease And Thalassemia

Four genes are involved in making the alpha globin part of hemoglobin—two from each parent. Alpha thalassemia occurs when one or more of these genes is variant or missing. Alpha thalassemias mostly affect people of Southeast Asian, Indian, Chinese, or Filipino origin or ancestry. Severe or moderate anemia results when more than two genes are affected. The most severe form of alpha thalassemia is known as alpha thalassemia major. It can result in miscarriage. Two genes are involved in making the beta globin part of hemoglobin—one from each parent. Beta thalassemia occurs when one or both of the two genes are variant. Beta thalassemias affect people of Mediterranean origin or ancestry (Greek, Italian, Middle Eastern) and people of Asian and African descent. The severity of illness depends on whether one or both genes are affected and the nature of the abnormality. If both genes are affected, anemia can range from moderate to severe. The severe form of beta thalassemia is also known as Cooley’s anemia. Cooley’s anemia is the most common severe form of thalassemia in the United States. A few signs and symptoms of thalassemia major appear in the first 2 years of life. Infants have life-threatening anemia and become pale and listless. They also have a poor appetite, grow slowly, and may develop yellowing of the skin and whites of the eyes (jaundice). The spleen, liver, and heart may be enlarged, and bones may be deformed. Adolescents with thalassemia major may experience delayed puberty.
Sickle cell trait partially protects people from the deadly consequences of malaria in the Mediterranean and North African regions. The most common problems of the disease are a combination of the sickle cell structure and the assignments of the beta thalassemia genes. The sickle cell mutation reflects a single change in the amino acid building blocks of the oxygen-transport protein, hemoglobin. This protein, which is the component that gives red cells their color, has two subunits. The alpha subunit is normal in people with sickle cell disease. The beta subunit has the amino acid valine at position 6 instead of the glutamic acid that is normally present. The gene that controls the production of the beta globin subunit of hemoglobin is located on chromosome #11 of the 46 human chromosomes. If only one of the beta globin genes is the "sickle" gene and the other is normal, the person is a carrier for sickle cell disease. If both beta globin genes code for the sickle protein, the person has sickle cell disease.
Sickle hemoglobin exists as isolated units in the red cells when they have oxygen bound. When sickle hemoglobin releases oxygen in the peripheral tissues, however, the molecules tend to stick together and form long chains or polymers. The sickle hemoglobin polymers are held together by very weak forces. The abnormal valine amino acid at position 6 in the beta globin chain interacts weakly with the beta globin chain in an adjacent sickle hemoglobin molecule. These rigid polymers distort the cell and cause it to bend out of shape. While most distorted cells are simply shaped irregularly, a few have a cresent-like appearence under the microscope.
Sickle cell disease, thalassemia, and disorders of iron metabolism are topics of interest to understand more things about genetics and blood problems. For more information click to http://sickle.bwh.harvard.edu/menu_sickle.html

[Arimas]

Cacio,

I think you're right about the Thalassemia...my doctor said he has different tests to check for Italians and Greeks etc.

Check here the map of sickle cell and malaria. I find interesting that they overlap closely except in North-East Africa. These maps must be approximative or/and Sickle Cell anemia appears only when malaria hit hard like all seasons. My guess is that North-East Africa is very dry and semi-desertic and has no or less malaria during the hot dry summer.

http://www.understandingrace.org/humvar/sickle_01.html


Arimas

[Arimas]

Thanks GregKiroKHR1bL1 for the wealth of info on the topic. I bookmarked the link for later reading.

[cacio]

Thanks for the links, very informative. I wonder if the lack of sickle cell in E Africa is simply due to the lack of data about the region. May be it simply wasn't sampled, or wasn't sampled correctly. I did a quick internet search, but couldn't find anything. It seems sickle cell anemia is present in S Arabia, Yemen and Oman, so it seems a little strange that it is not present in Somalia.

A link from the UNO confirms that malaria is indeed present in Somalia:
"Malaria is one of the leading causes of morbidity and mortality in Somalia, with epidemic peaks in the rainy seasons. Drug resistant malaria is already present in Somalia..."

cacio

[Arimas]

I just thought about the hot dry conditions of some places like where I was born where no mosquito can survive in the hot summer and that reduces the chances of getting malaria (further from the Equator).

But definitely, lack of data could be true as well. Also in the map, that grey malaria free area that is supposed to be Ethiopian highlands is too approximative as well. Somalia has malaria as the map shows and it will increase with the climate changes according to the ScienceDaily:



"The highlands of Ethiopia, Kenya, Rwanda and Burundi—currently malaria free—become highly suitable for malaria mosquitoes by the 2080s. Malaria is also likely to rise in the highland areas of Angola and Somalia, areas currently with low levels of malarial cases."


source: http://www.sciencedaily.com/releases...0410141336.htm

[GregKiroKHR1bL1]

The map does not include how the disease is spreading around the world due to population migration. However, doctors are forming clinical studies on race and medicine.

http://www.racesci.org/racescinow/he...drm.index.html

It is interesting how the disease seemed to move from central Africa into the India . . .

[Arimas]

Can't see where they're talking about Sickle Cell and migrations.

[GregKiroKHR1bL1]

They usually talk about those things in medical school when they look at the data. I have no idea why people do not make the proper notes.