Sickle cell anaemia : Sickle cell anaemia = Sickle Cell disease
Was first described in 1910
Serious symptoms
Fever
Extreme pain in bones and joints
Red blood cells were sickle-shaped
Severe anemia (low number of red blood cells)
Premature death
A recessive trait. B. Autosomal recessive disorders
Slide 2 :
Slide 3 : Sickle-cell disorder occurs in individuals who are homozygous for the mutant allele and sickle cell trait occurs in heterozygous individuals .
People with the sickle-cell trait generally have milder anemia and are not as seriously affected as those with sickle-cell disorder. Disorder or a Trait ?
Slide 4 :
Slide 5 : Normal hemoglobin…….Hb-A.
Two pairs of polypeptide chains
Alpha chains and beta chains
Almost equal in size
Alpha chains have 141 amino acids
beta chains have 146 amino acids.
Slide 6 : The genes that encode the two polypeptide chains are located on the part of chromosome 11.
Sickle-cell hemoglobin, Hb-S, differs from Hb-A by only one amino acid placed sixth in the second beta chain, yet this single change alters the molecule to such an extent that it effects RBC phenotypically.
Normal Hb-A individual has this amino acid glutamic acid but Hb-S has valine.
Thalasaemia : Thalasaemia Impairment of synthesis of a single kind of Hb-chain
More common in Meditarranean countries ("thalasa"= sea).
The a-chain thalassaemia is also prevalent in S.E. Asia, with an occurrence of I in 100 in Thailand.
Slide 8 : Occur due to mutation of 'Regulator gene'.
Classified into two kinds
Alpha -chain Thalassaemias
Synthesis of alpha -chains are repressed
Compensatory increase in synthesis of other chains
Ether beta-chains or gamma-chains.
Slide 9 : Beta-chain Thalassaemia
More severe
Also called Thalassaemia Major.
When the thalassaemia gene represses b-chain synthesis
Excess of alpha-chains occur.
Severe anaemia
First described by Cooley,
Called Cooley's anaemia.
Infants suffering from this desease have "Mongoloid" features
Stunted growth.
Severe heamolytic anaemia.
Thalassemia : Thalassemia
Cystic fibrosis : Cystic fibrosis Most common lethal genetic disease
Afflicting Caucasians.
Caused by an autosomal recessive mutation
Disease affects tissues called secretory epithelia, which are responsible for transporting water and salt at the interface between the bloodstream and the external environment (e.g., in the lungs, intestine, and sweat glands).
Cystic fibrosis : Cystic fibrosis
Slide 13 : Abnormal transport ation
Causes buildup of thick mucus in the affected organs.
Failure of the pancreas to secrete digestive enzymes into the intestine,
Thick mucus in the lungs
High levels of salt in the sweat.
The defective gene has been proved to be associated with chromosome 7.
Haemophilia : Haemophilia Deficiencies of coagulation
Bleeding may occur spontaneously or after only minor trauma.
Deficiency of different blood clotting factors.
The most common type (classic hemophilia) is hemophilia A, absence of factor VIII.
People with hemophilia B lack factor IX.
Hemophilia A and B occur primarily among males, since these are sex-linked recessive disorders.
A milder form is hemophilia C, a lack of factor XI, which affects both males and females. Sex linked recessive disorders
Hemophilia : Hemophilia
Slide 16 :
Slide 17 : Hemophilia is characterized by
Nosebleeds,
Blood in the urine,
Hemorrhages in joints that produce pain and damage.
Treatment
Transfusions of fresh plasma or concentrates of the deficient clotting factor to relieve the bleeding tendency.
Slide 18 : A high incidence of hemophilia has troubled the royal families of Europe. The first royal hemophiliac seems to have been a son of Queen Victoria (1819-1901) of England.
It is likely that the hemophilia allele arose through a mutation in one of the gametes of Victoria's mother or father, making Victoria a carrier of the deadly allele.
Hemophilia was eventually introduced into the royal families of Prussia, Russia, and Spain through the marriages of two of Victoria's daughters who were carriers.
Slide 19 :
G-6-PD deficiency syndrome : G-6-PD deficiency syndrome A mutation present in some populations
Causes a deficiency of the enzyme-G-6-PD
With impairment of generation of NADPH
Red cell hemolysis occur when subjected to drugs such as antimalarials, like primaquin and aspirin etc.
Naphthalene toxicity : Naphthalene toxicity
G-6-PD deficiency syndrome : G-6-PD deficiency syndrome
Diabetes mellitus : Diabetes mellitus An elevation of glucose in the blood (hyperglycemia).
Also loss of glucose in the urine (glucosuria).
Hallmarks of diabetes mellitus are the three "polys".
An inability to reabsorb water, resulting in excessive urine production (polyuria); excessive thirst (polydipsia); and excessive eating (polyphagia).
Diabetic pancreas : Diabetic pancreas