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Genetic_Flashback:
Genetic disorders: 1- Mendalian disorders:-Autosomal recessive:
-Autosomal dominant
-X-linked recessive.
-X-linked dominant.
2-
Chromosomal disorders:
- Neumerical ( e.g. trisomy21)
- Structural.
3-Multigene:DM-2
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Autosomal_recessive :
Carrier
X carrier (both parents must be carriers to the mutant gene.
25% of offspring are affected (rr).
25% are not affected (RR).
50% are carriers (Rr)
Mutant gene (r).
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Clinical_Example:
Neurological 1-Fredrich Ataxia.
Non-Neurological:
Hematology:
1- Sickle cell Anemia
2- Thalassemia.
3-Chediak higashi syndrome
4-Shwachman-Diamond syndrome (low WBC, skeletal deformity, Malabsorption)
5- Fanconi Anemia (pancytopenia + skeletal deformities).
Other:
1-Cystic fibrosis.
2- Hereditary hemochromatosis.
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NB:
A gene has two alleles.
Alleles are either dominant or recessive.
Each parent contribute with an allele.
Dominant trait (R).
Recessive trait (r).
Recessive trait only appear when both alleles are
(rr).
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My_notes
