What are some of the causes of Hemophilia?
Saturday, June 9, 2012
11:00 PM
- Hemophilia A - Recessive X-linked genetic disorder
- lack of functional clotting Factor VIII
- represents 80% of hemophilia cases - Hemophilia B - Recessive X-linked genetic disorder
- lack of functional clotting Factor IX
-approximately 20% of hemophilia cases - Hemophilia C - Autosomal genetic disorder (i.e. not X-linked)
-lack of functional clotting Factor XI.
-not completely recessive.
http://www.hemophilia.in/images/hemophilia-inherited-chart3.jpg
A diagram depicting the possible outcomes of offsprings with haemophilic father & carrier of haemophilic gene in mother.
- Females have 2 X-chromosomes while males have 1 X-chromosome & 1 Y-chromosome
- Mutations causing the disease are X-linked
- A woman carrying the defect on one of her X-chromosomes may not be affected by it, as her other X-chromosome can express itself to produce the necessary clotting factors. - However, the Y-chromosome in men has no gene for factors VIII or IX
- If the genes responsible for production of factor VIII or factor IX present on a male's X-chromosome are deficient, the Y-chromosome is unable to produce the necessary clotting factors. So, the deficient gene is not masked and he will develop the illness.
Severity
Numerous different mutations which cause each type of hemophilia.Due to differences in changes to the genes involved, patients with hemophilia often have some level of active clotting factor.
- < 1% active factor are classified as having severe hemophilia
- 1-5% active factor have moderate hemophilia
- 5-40% of normal levels of active clotting factor have mild hemophilia
Links: http://en.wikipedia.org/wiki/Haemophilia#Causes
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