X linked recessive disorder

Overall Basics on X-Linked Recessive Disorder.

1. X-Linked R ecessive D isorder Md. Tangigul Haque Reg. No. : 2011433023

2. P assed down through families through one of the X chromosomes If only one gene in the pair is abnormal, the disease does not occur or it is mild Someone who has one abnormal gene is called a carrier Carriers can pass abnormal genes to their children The term X-linked recessive usually refers to “Sex-linked recessive”. 1 Reference :1. Fogel BL, Geschwind DH. In: Daroff RB, Fenichel GM, Jankovic J, Mazziotta JC.Fogel BL, Geschwind DH. In: Daroff RB, Fenichel GM, Jankovic J, Mazziotta JC. Bradley's Neurology in Clinical Practice . 6th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 40 . X -Linked I nheritance

3. Males affected almost exclusively A single recessive gene on that X chromosome will cause the disease . T he gene alteration can be transmitted from female carriers to sons A ffected males cannot transmit the condition to their sons . Fig: X-linked recessive inheritance condition Reference: Dobyns , William B.; Filauro , Allison; Tomson, Brett N.; Chan, April S.; Ho , Allen W.; Ting, Nicholas T.; Oosterwijk , Jan C.; Ober, Carole (2004). "Inheritance of most X-linked recessive traits” . American Journal of Medical Genetics 129A (2): 136. Features o f X-Linked R ecessive I nheritance

4. Fig: X-linked recessive, carrier mother Fig: X-linked recessive, affected father Reference: Wattendorf DJ, Hadley DW Am Fam Physician, Family history: the three-generation pedigree. 2005 Aug 1; 72(3):441-8 .[PubMed] Reference : Wattendorf DJ, Hadley DW Am Fam Physician, Family history: the three-generation pedigree. 2005 Aug 1; 72(3):441-8.[ PubMed ] X-Linked R ecessive – In C ase o f C arrier M other A nd Affected F ather

5. Most types are caused by a gene located on the X chromosome Red green colorblindness is the most common type Fig: Ishihara Test Reference : Troscianko T, Benton CP, Lovell PG, Tolhurst DJ, Pizlo ZPhilos Trans R Soc Lond B Biol Sci. on v isual perception. 2009 Feb 27; 364(1516):449-61 .[PubMed] Example 1 - Colorblindness

6. Much rare than colorblindness -1 in 10,000 males -1 in 100,000,000 females Hemophilia A is a disorder where the blood cannot clot properly due to a deficiency of a clotting factor called Factor VIII. This results in abnormally heavy bleeding that will not stop, even from a small cut. 2 Reference: 2. Sankiewicz P, Lupsik JR. Gene, genomic, and chromosomal disorders. In: Goldman L, Ausiello D, eds.Sankiewicz P, Lupsik JR. Gene, genomic, and chromosomal disorders. In: Goldman L, Ausiello D, eds. Goldman's Cecil Medicine . 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 40. Example 2 - Hemophilia

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