Genetics Flashcards
super (32 cards)
What are the types of chromosomal disorders?
Numerical abnormalities
Structural abnormalities
Mosaicism
Chimera
What is the most common mating type in ADI?
Heterozygous affected × Homozygous unaffected
How does ADI manifest?
In the heterozygous state (one mutant + one normal allele)
What is the pattern of transmission in ADI?
Both sexes affected equally
Passed from one generation to the next (vertical transmission)
Transmitted by both sexes
What are the chances of inheritance for a child of an affected ADI parent?
50%
What is non-penetrance?
A person has the mutant gene but does not show symptoms
What is variable expressivity? Give an example.
Different people show different symptoms.Example: Marfan syndrome
Name diseases due to ADI.
Nervous: Neurofibromatosis, Huntington’s, Myotonic dystrophy, Tuberous sclerosis (NHMT
GI: Familial polyposis coli
Urinary: Polycystic kidney disease
Skeletal: Marfan syndrome, Ehlers-Danlos, Osteogenesis imperfecta, Achondroplasia (MEOA)
Haemato: Hereditary spherocytosis, Von Willebrand disease (SV)
Metabolic: Familial hypercholesterolemia
What is the usual mating in ARI?
Two heterozygotes (unaffected carriers)
How does ARI manifest?
Only in the homozygous state (mutant allele from both parents)
How is ARI transmitted?
Transmitted by both sexes
Both sexes equally affected
What are the offspring chances in ARI?
25% Affected (homozygous mutant)
50% Carriers (heterozygotes)
25% Unaffected (normal)
What is the pedigree pattern?
ARI
Horizontal — siblings affected, not passed from parent to child
What is consanguinity and its importance in ARI?
Marriage between close relatives
More common in rare ARI diseases
What happens if an affected person marries an unaffected carrier?
Offspring have 50% chance of being affected
Name diseases due to ARI.
Albinism (ATGC) (CDSP)
Thalassemia
Galactosemia
Cystic fibrosis
Congenital adrenal hyperplasia
Deaf mutism
Phenylketonuria
Spinal muscular atrophy
What mating types are involved? X-LINKED DOMINANT INHERITANCE
Heterozygous female × Normal male
Hemizygous affected male × Normal female
Who is affected in X-linked dominant disorders?
Both sexes, but females more frequently
Males more severely affected
What is the inheritance pattern?
X linked dominant
All daughters of affected males are affected
No male-to-male transmission
50% chance for children of affected females
Name diseases due to X-linked dominant inheritance.
Vitamin D–resistant rickets
Pseudo-hypoparathyroidism
X-LINKED RECESSIVE INHERITANCE
Q: What mating type is typical?
Unaffected carrier female × Normal male
Who is mainly affected in X-linked recessive?
Males only
Can females be affected?
x linked recessive
Rarely — only when homozygous mutant
What is the transmission pattern?
X linked recessive
Affected males → all daughters are carriers, no sons affected
Carrier females → 50% sons affected, 50% daughters carriers
