Pedigree Concepts Flashcards
“Genetic counseling” was coined by
Sheldon Reed
In 1971, the first batch of trained genetic counselors were trained; nowadays, should have a ____
masters degree
4 reasons for patient to see genetic counselor
family history of Cancer, multifactorial disease, abnormal chromosomes, single gene disease
2 genetic testing techniques
karyotype and amniocentesis
Genetic analysis method to determine disease
family history
Genetic testing technique
Genetic counselor deduce dominance and distinguish autosomal from X-linked inheritance
Pedigree analysis
family tree,” drawn with standard genetic symbols, showing inheritance patterns for specific phenotypic characters
pedigree chart
Squares represent ___ and Circles represent ____
square: males ; circles:females
Shaded squares or circles signify the presence of ___
trait of interest
Rows are ____, labeled with ____.
generations, roman numerals
t/f: Within each generation, or row, family members may be labeled numerically from right to left and referred to by their generation and position.
false, left to right
horizontal line connecting two parents is called a
marriage line
A vertical line of descent extending downward from a marriage line connects to a horizontal ____
sibling line
Individuals connected to the line of descent via the sibling line are ___.
off spring
One mutated allele causes the disease Each affected person usually has one affected parent Appears in every generation of an affected family (Vertical)
Autosomal dominant
Inheritance Pattern: Marfan syndrome; Achondroplasia; Huntington disease; Myotonic dystrophy
Autosomal dominant
inheritance pattern: Two mutated alleles needed to cause the disease Parents are usually unaffected heterozygotes Not typically seen in every generation (Horizontal).
Autosomal Recessive
Inheritance pattern: Females are more frequently affected than males no male-to-male transmission
X-linked dominant
Inheritance pattern: Males are more frequently affected than females Both parents of an affected daughter must be carriers Fathers cannot pass X-linked traits to their sons
X-linked Recessive
Inheritance pattern: Only females can pass on mitochondrial conditions to their children (maternal inheritance) Both males and females can be affected Can appear in every generation of a family
Mitochondrial
Inheritance Pattern: Beta thalassemia; Cystic fibrosis; Homocystinuria
Autosomal Recessive
Inheritance Pattern: Rett syndrome; Hypophosphatemia
X-linked dominant
Inheritance Pattern: Hemophilia; Duchenne Muscular Dystrophy
X-linked Recessive
Inheritance Pattern: LHON: Leber’s hereditary optic neuropathy
Mitochondrial
All except one pertains to Autosomal Dominant
a. approximately half of everybody
b. males and females affected
c. consanguinuity
d. all generations
c. cosanguinity
All except one pertains to Autosomal Recessive
a. every child of affected mother is affected
b. Rare
c. Skips generations
d. Males and females affected
e. Consanguinity
a. every child of affected mother is affected