pedigrees

What is a pedigree?

A tool for mapping inheritance patterns and inferring information about alleles in families.

What is an example of an autosomal dominant trait?

Huntington's disease.

What are the characteristics of an autosomal dominant trait?

Affected parent will have affected children, does not skip generations, and is equally likely in males and females.

What is an example of an autosomal recessive trait?

Cystic fibrosis.

What are the characteristics of an autosomal recessive trait?

Both parents must carry at least one allele, skips generations, and is equally likely in males and females.

What does consanguinity refer to in pedigree analysis?

Mating among related individuals which increases the chance of inheriting a rare trait.

What is the genetic bottleneck or founder effect?

Alleles shared in a population due to common ancestry.

What is a Y-linked trait?

A trait caused by an allele of a gene on the Y chromosome, appearing only in males.

What is a mitochondrial trait?

A trait that is maternally inherited, where affected mothers pass on the condition.

What is the significance of twin studies in genetics?

They help determine the genetic basis of traits by comparing concordance rates between monozygotic and dizygotic twins.

What is the probability that siblings share an allele from a parent?

50% probability.

What is the pattern to look for in X-linked recessive traits?

More likely to appear in males and skips generations.

What is the pattern to look for in X-linked dominant traits?

Affected individuals have at least one affected parent and are more likely to be female.

What is the probability that an individual indicated in a pedigree is a heterozygote if both parents are recessive?

67% chance.

What is the probability that an unrelated individual indicated in a pedigree is a homozygote?

If the trait is rare, most likely AA; if common, 1/3 chance of AA.

What is an example of a complex pedigree?

Bipolar disorder, which may involve multigene traits and environmental effects.

What is the significance of familial similarity in pedigree analysis?

Close relatives share many alleles, with a 50% probability of sharing an allele.

What is the main focus of genetic counseling?

Predicting genotypes and phenotypes from family trees.

What is Waardenburg syndrome?

An autosomal dominant trait characterized by deafness, fair skin, visual problems, and a white forelock.

What are some examples of autosomal recessive traits?

Albinism, Galactosemia, Tay Sachs disease, and Phenylketonuria.

What is the trait caused by an allele of a gene on the X chromosome?

X-linked trait.

What is the probability of having a child with a trait if both parents are carriers?

Depends on the type of trait; for autosomal recessive, 25% chance.

What is the role of environmental effects in genetic traits?

They can influence the expression of traits, as seen in twin studies.

What is the inheritance pattern of traits caused by multiple alleles?

Different alleles of the same gene can combine to show a trait.

What is the definition of a trait that is 'pseudo-dominant'?

A Y-linked trait that appears dominant because there is no homologue to cover it up.