Genetic Diseases

Question 1

Describe inheritance, pathophysiology and S&S of: Cystic Fibrosis

Answer 1

AR (25% risk to child from two carrier parents)

abnormal CF ransmembrane conductance regulator gene (CFTR) responsible for Chloride channels

cor pulmonale/lung disease, pancreatic insufficiency, failure to thrive

Question 2

Describe inheritance, pathophysiology and S&S of: Sickle Cell Anemia

Answer 2

AR

single point mutation in beta chain in Hgb creating a Hgb S that forms polymers when deoxygenated

Vaso-occlusive pain crises, shortened life expectancy, hemolytic anemia

Dx: Hgb Electrophoresis

Question 3

Describe inheritance, pathophysiology and S&S of: Tay Sachs Disease

Answer 3

AR. “Founder Effect” (high frequency of mutant gene in population ‘founded’ by small ancestral group of carriers)

deficiency in Hexoaminidase A enzyme responsible for GM2 ganglioside degradation (a lot especially in the brain gray matter)

loss of alertness, hyperacusis, intellectual and neurologic degeneration, myoclonic and akinetic seizures, cherry red macula

Question 4

Describe inheritance, pathophysiology and S&S of: Beta Thalassemia

Answer 4

AR point mutation

impaired Beta chain production leading to excess alpha
chains

low MCV anemia

Dx: Hgb Electrophoresis

Question 5

Describe inheritance, pathophysiology and S&S of: Alpha Thalassemia

Answer 5

AR gene deletion

4 gene deletion: Hb Bart –> Fetal hydrops, severe anemia, splenomegaly, 100% Hba4 (No HbF, No HbA)

3 gene deletion: Hb H –> beta chain accumulation, moderate anemia some Hb Bart, some HbH then HbA after Bart disappears

2 gene: Alpha Thalassemia –> mild microcytic anemia, normal electrophoresis

1 gene: silent carriers, MCV