Pedigrees Flashcards
chromosomal disorders
aneuploidy: addition or loss of chromosomes
indels
translocation: balanced and unbalanced
usually are sporadic during gamete formation but can be inhertied, result in complex phenotypes
22q11 deletion
Microdeletion at chromosome 22
Robertsonian translocation
Sotos syndrome
chromosomes are inapporpriatly together
Complex disorders
caused by mutations at more than one gene, or a combo of genetic and environmental factors
Dont display pedigree inheritance but show familial clustering or aggregation
monogenic disorders
determined by a single mutant gene, can display different inheritance patterns, rare (6-8%)
allelic variation contributes to the disorders
Monogenic disorders exhibit characteristic inheritance patterns based on: location of the gene (chromosomal autosomal or sex, or mitochondrial), dominance
Autosomal dominant inheritance
affected gene is located on one of the autosomes. The mutant allele determines the phenotype. An autosomal dominant pedigree has each affected individual has an affected parent. Normal parents have normal kids, males and females are affected in equal proportions every gen has an affected individual
huntingtons, marfan syndrome
autosomal recessive
mm shows mutant phenotype, parents of the affected indivdual can be normal, both parent are usually carriers, consanguineous marriage.
CF, sickle cell disease
X linked dominant inheritance
NO male to male transmission, all daughters of the affected male are affected. Affected females w/ normal male, 50% of all male and female offspring are affected. Females are more likely to be affected than males, but males are more severly afected
incontinentia pigmenti
X linked recessive
any male carrier shown phenotype, and females have to be hmozygous. never passes from male to male. Affected grandfather to carrier daughter to 1/2 of grandsons
haemophelia
Ylinked
disease only observed in males, will always be male to male
Mitochondrial inheritance
all kids of an affected female hace the disease (leber disease)
Variable exprecissivity
affected individals may express all of the symptos or only a few
incomplete penetrance
a person with the mutant genotype may not express the disease phenotype
Genetic anticipation
members of a pedigree exhibit a progressively earlier onset of increased severity of the disease (huntingtons)
Mosaicism
mutation originates as a somatic mutation during embryogenisis. 2 cell types are present one normal and one mutant, risk of fututre offspring are the same as from an affected parent
