Description
ppt on anaemia in children
Explanation & Answer
Find the attached document,I have specifically talked about sickle cell anaemia
SICKLE CELL DISEASE
kibaru
EPIDEMIOLOGY
Incidence
Sickle hemoglobin is the most common abnormal
hemoglobin found in the United States
approximately 8% of the African-American
population has sickle cell trait.
The expected incidence of sickle cell disease
(SCD) at birth is 1 in 625.
GENETICS
Sickle cell disease is transmitted as an
incomplete autosomal dominant trait.
Homozygotes (two abnormal genes) do not
synthesize hemoglobin A (HbA)
red cells contain 90–100% hemoglobin S (HbS).
Heterozygotes (one abnormal gene) have red cells
containing 20–40% HbS
HbS arises as a result of spontaneous mutation
and deletion of the β-globin gene on chromosome
11
which results in selective advantage against
Plasmodium falciparum malaria in carriers
(balanced polymorphism).
CO-INHERITANCE
. α-Thalassemia (frequency of 1–3% in African
Americans) may be co-inherited with sickle cell
trait or disease.
Individuals who have both α-thalassemia and
sickle cell anemia are less anemic than those who
have sickle cell anemia alone.
However, α-thalassemia trait does not appear to
prevent frequency or severity of vaso-occlusive
complications.
CLASSIFICATION
Results of DNA polymorphism linked to the βs
gene suggest that it arose from three independent
mutations in tropical Africa:
1. Benin–Central West African haplotype (the most
common haplotype)
2. Senegal–African West Coast haplotype
3. Bantu–Central African Republic (CAR) haplotypen
southwest Saudi Arabia.
In Caribbean and North American patients of African
heritage
with SCD,
50–70% of chromosomes are Benin
▪ 15–30% are Bantu-CAR
▪ 5–15% are Senegal.
▪
The Benin and Senegalese patients have higher
levels of fetal hemoglobin (HbF) and fewer dense
cells compared with Bantu-CAR patients.
Patients with Senegal haplotype have the least
severe disease, whereas patients with BantuCAR haplotype have most severe disease.
PATHOPHYSIOLOGY
A single amino acid substitution (valine for glutamic acid)
occurs in the 6th position of the β-chain in the β-polypeptide
chain in chromosome 11
This leads to formation of Abnormal hemoglobin
On Polymerization in vivo sickling occurs
There i...
Review
Review
