Is it true that  if mosquitoes bite  "AA"person, such person will fall sick(malaria)  but if the mosquitoes bite "AS" person there will be no malaria

yea. it's called "heterozygote advantage"

but as AA, once you have passed childhood without dying, it means that your immune system is strong enough to resist malaria so you're just as fine as the AS person . the AA children with weak immune system will have died from malaria in infancy or childhood.

I believe its true.

people with sickle cell have only a slim chance to conract malaia. those who do not carry the marker have no resistance to malaria

From my own understanding, the S gene is a mutation of the normal A gene in response to frequent malaria attacks which emerged probably hundreds generations ago.
The evolutionary intention here was to create a super ''AS'' haemoglobin that would resist the malaria parasite. Of course the purpose was soon defeated when SS emerged as a result of combining AS with AS haemoglobin.
I would say AS rather than SS have increased resistance to malaria. Infact sicklers tend to come down with malaria just as often as AA genotype people.

From my own understanding, the S gene is a mutation of the normal A gene in response to frequent malaria attacks which emerged probably hundreds generations ago.
The evolutionary intention here was to create a super ''AS'' haemoglobin that would resist the malaria parasite. Of course the purpose was soon defeated when SS emerged as a result of combining AS with AS haemoglobin.
I would say AS rather than SS have increased resistance to malaria. Infact sicklers tend to come down with malaria just as often as AA genotype people.

Lamii:

yea. it's called "heterozygote advantage"

but as AA, once you have passed childhood without dying, it means that your immune system is strong enough to resist malaria so you're just as fine as the AS person . the AA children with weak immune system will have died from malaria in infancy or childhood.

, dis is 1 thing i dig nland 4 facts , sharp info, timely . I blv it

i really dont know if there's a connection, but i'm AA and as much as i take anti-malaria drugs and spray my home with insecticides and generally try and prevent mosquitoes from biting, i always get malaria at least 3 times a year, i always test negative for everything else, but malaria always somehow finds me and takes me down,

@MCLOVIN
check your post. . . seems like you contracted yourself in this statement.

I would say AS rather than SS have increased resistance to malaria. Infact sicklers tend to come down with malaria just as often as AA genotype people.

i disagree. from my own understanding, the malaria parasite (plasmodium) cannot survive in the blood stream with the S gene. that's we hardly hear cases of sicklers havng malaria (i personally have not seen one). AS have less malaria attacks because of the recessive S gene present in its genotype but AA are the most prone to malaria. using myself as a personal example now, as an AS, i can count the number of times i've had malaria in mylifetime with my fingers and boy have been bitten by mosquitoes. and when i eventually do, i never complete my dosage before i getcompletely healed.

Check your post you and mclovin are saying the exact same thing.
The''Heterozygous advantage''   mentioned above is right. ''AA and SS have no special resistance to malaria, they  are''Homozygous''.
Tell hundreds of sickle cell patients in the wards down with malaria that if it wasnt why is daraprim(outdated) and Proguanil standard prophylactic medication for SS patients? Malaria kills more SS patients than anything else in this country visit any inpatient ward or out patient clinic fnd out for yourself . This is clinical, stuff you see with your own eyes, thers no debate here.

^^^
Thanks area thug !
@dominique
Lets look carefully at  the term HeteroZYGOUS ADVANTAGE. The advantage here is ''heterozygous'' im also AS and I can attest to you waht u said about little or no incidence of malaria. Ive not had since resettled here, about 3 years. Thats because we are HETEROZYGOUS ie AS.
The S gene no doubt is resistant to malaria but when you have a homozygous SS that advantage is lost. Capish ?
Believe you me, Sicklers DO come down with malaria at least in Nigeria. Take up face's challenge and visit a haematology ward sometime.
You can lose your job prescribing heaven and earth for a sickler while leaving out malaria prohylaxis .
I understand youre taliking from experience when you say you havent seen many SS with malaria but your experince isnt clinical or is it ?

@MCLOVin
my experience is mostly personal and a bit clinical. but how does the S gene is resistant to the parasite, how come the SS genotype are still prone to malaria. you didn't explain properly.
i have worked in an hematology lab (albeit briefly) and not for once did we observe malaria traits in sicklers.

Hi Dominique,
Lets try to keep it simple and view it from the perspective of heterozygous advantage.

The S gene is a mutant gene which emerged to help the african resist malaria infection. The gene was meant to act in combination with normal ''A'' hemoglobin to create a heterozygous resistant ''AS'' hemoglobin. Some people will even tell you that AS ppl are stronger and bigger than AA - Thats what genes do over time, they adapt to their environment to produce species that are better suited to survival in both physical and genetic attributes.

Some sicklers, DO have factors that make them more resistant than the other sickler , in the lab at electrophoresis the result may come up as SS + f ,or SC + f, that factor connotes some resistance to malaria but not only that, it may also indicate that the hemoglobin doesnt sickle as easily and a lot of other things only a hematologist or clinical pathologist can tell you.
At the molecular level in a petri-dish these sicklers can be said to be healthier than others.
But as I said before, when S combines with S, heterozygous advantage is lost.

Also very important to note that sicklers are generally MORE PRONE to any type of infection than normal folk, some books even go as far as saying patients, with sickle cell disorder are more or less IMMUNOCOMPROMISED, this so because :

1. They have low amount of oxygen in their blood frm the anaemia.
2. They are COMPLEMENT deficient, complements are proteins necessary for succesful immune response, they dont have very much of it.
3. Even though, they have relatively high white cell count , the white cells don't always function properly.
4. They have a higher micro-nutrient requirements than normal ppl because of the high turnover of cells. They can easily become deficient in zinc, folate, selenium, copper and other minerals important for a properly functioning immune system.
This list is by no means exhaustive but i'll stop here.

So this is why we try to 'cover' them with prophylaxis from chest infections by pnuemoccocus, bone marrow infection from salmonella etc. with vaccinations.
As you know, there is no vaccine for malaria yet, otherwise we would ask them to go for a malaria 'shot' as well.

Malaria parasite, the plasmodium falciparum has high affinity for oxygen rich blood which is what you find in individuals with AA blood genotype when you compare to people with SS and AS genotype hence, the increased incidence of malaria in people with AA genotype. AS genotype individual does not suffer malaria that much because they have the S gene which because of the low oxygen tension can not sustain the survival of of the plasmodium.

Dominique,
SS suffer from malaria alot. Being SS means they do not have the protection that an "A" gives when it combines with an "S".

So also do AA not have the "S" protection. Go to hospital wards in Nigeria, malaria is one of the major reasons SS are admitted.

It is the malaria which in turn leads to othe problems, anemia, lowered immunity hence high chances of getting infection.

SS in the US and UK do not suffer from malaria.

Hi Survivor,
Are you SS ?

MCLOVIN:

Hi Survivor,
Are you SS ?

I'm curious sir, why did you ask? Cos of my name?.
I ain't but have my own health challanges.

Hi survivor69
I was just hoping someone with (SS) firsthand experience would tell us their perspective.
No problems.
Cheers.
This is MCLOVIN.

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Hah, i'm AA and O+ i've never had malaria! I'm in my twenties and d only time i remember ever being sick enough 2 be admitted in a hospital 4 a few hours was wen i was eight. I get mosquitoe bites often.

sashaa:

Hah, i'm AA and O+ i've never had malaria! I'm in my twenties and d only time i remember ever being sick enough 2 be admitted in a hospital 4 a few hours was wen i was eight. I get mosquitoe bites often.

I weak oo, , i am AA also and have never been to the hospital since 1991, i hardly take drugs and i have been bitten by mosquitoes often time but malaria? nah i am yet to get sick for few hours this year and have never had cause to be indoors for more than one day because of malaria. so i don't think malaria and the genotype thing really work or 100% accurate. also in my twenties (late)

Im AA, A+. I get malaria wenever i expose myself 2 mosquitoes.

personally, I dont think there is any link. My elder sister is 'AA' but rarely suffers from malaria yet those of us(my brother and I) with the 'AS' genotype get affected easily.

@ Dominique, Mclovin, Jumpmasta, Survivor et al
Human blood has only revealed a tiny fraction of its secrets to us.
We only talk of what we know so far, its too soon to postulate rules and theories. Maybe in the next 50 years.

[quote author=Survivor9]Dominique,
SS suffer from malaria alot. Being SS means they do not have the protection that an "A" gives when it combines with an "S".

So also do AA not have the "S" protection. Go to hospital wards in Nigeria, malaria is one of the major reasons SS are admitted.

It is the malaria which in turn leads to othe problems, anemia, lowered immunity hence high chances of getting infection.

SS in the US and UK do not suffer from malaria.

Malaria is not the major reason SS are admitted crises (joint pains), as a sickler, i've been admitted to the hospital on the account of malaria once in my lifetime and i am 23years of age.

i'm 'AA' blood group and i fall sick everytime i have a mosquito bite. What can i do?

From contributions so far,its safe to say that blood genotype alone are not enough indications of susceptibility to malaria but when combined with blood group they become significant