Autoosomal Inheritance

Question 1

Mendelian traits

Answer 1

One gene expresses a certain phenotype which can be affected by a mutation.

Question 2

Pedigree

Answer 2

Graphical representation of family relationships and the occurrence of a particular disease in the family members

Question 3

Proband (index case or propositus)

Answer 3

1st person in whom the disease is observed; usually indicated by an arrow on a pedigree

Question 4

Autosomal Dominant Disorders (ADD) or Conditions

Answer 4

Seen in every generation; both genders are affected; dominant allele has to be present; most affected individuals are heterozygotes; if one parent is affected, there is 50% chance of children getting affected

Question 5

Commonly-encountered ADDs

Answer 5

Familial hypercholesterolemia
Polycystic kidney disease
Neurofibromatosis Type I
Hereditary Spherocytosis
Marfan Syndrome
Huntington Disease

Question 6

Autosomal Recessive Disorders (ARD)

Answer 6

Skips one or more generations; presence of carriers; affected individual must have two parents that are carriers (25%); both genders affected in equal proportions; consanguinity is implicated; if one parent is a carrier and other is affected, chances of child getting affected is 50% (quasidominant inheritance)

Question 7

Common ARDs

Answer 7

Sickle Cell Anemia
Cystic Fibrosis
Tay-Sachs disease
Phenylketonuria
Glycogen storage diseases
Galactosemia

Question 8

Complete dominance

Answer 8

States that the dominant allele completely masks the effects of the recessive allele

Question 9

Factors that affect expression of disease-causing genes

Answer 9

De novo mutations
Germline mosaicism
Reduced penetrance
Age-dependent penetrance
Variable expression
Allelic heterogeneity
Locus heterogeneity
Pleiotropy
Consaguinity