Inheritance and Disease Genes

A set of flashcards covering key concepts from the lecture on inheritance and disease genes.

What defines autosomal dominant inheritance?

An affected person usually has one affected parent and a 50% risk for their children to be affected.

What is the principle of uniformity in Mendelian inheritance?

All F1 offspring of homozygous parents with different alleles will be identical and heterozygous.

What does the principle of segregation state?

Only one allele will be transmitted from parent to offspring, resulting in a 3:1 phenotype ratio.

What is the Hardy-Weinberg equilibrium?

A principle that describes the distribution of alleles in a population under certain conditions.

What is the significance of the gene pool in genetics?

The total collection of genes and their variants in a population.

What is the recurrence risk of an autosomal recessive trait?

25% for each child after the birth of an affected child.

In Mendelian genetics, what does the term 'proband' refer to?

The individual in a pedigree who is the first affected family member to be studied.

What is the risk of a male inheriting an X-linked recessive disease if his mother is a carrier?

50% risk of being affected.

How does one determine if a trait is autosomal dominant?

If an affected individual has an affected parent and the trait appears in every generation.

What is meant by 'hemizygous' in X-linked inheritance?

Males have only one X chromosome, therefore only one allele for X-linked genes.

What does the principle of independent assortment state?

Separate loci segregate to offspring independently of one another.

How is a pedigree used in genetic counselling?

To document family history regarding disease patterns and inheritance.

What alleles signify a carrier of cystic fibrosis?

The presence of one normal allele (A) and one defective allele (a).

What does the Hardy-Weinberg Law allow geneticists to calculate?

Frequencies of genotypes and alleles in a population.

What is the distribution ratio of two phenotypes according to the principle of independent assortment?

9:3:3:1.

What are the common characteristics of autosomal recessive diseases?

Affected individuals usually have unaffected parents who are carriers.

What role do environmental factors play in human traits?

They interact with genetic factors to determine most human traits.

What is the significance of carrier testing?

To identify individuals who may pass on a genetic disorder to their offspring.

What gene mutation causes Tay-Sachs disease?

Mutations in the HEXA gene.

What are the modes of inheritance for genetic diseases?

Autosomal dominant, autosomal recessive, X-linked recessive, X-linked dominant, Y-linked.

What is a consanguineous mating?

Mating between individuals who are closely related.

How does mutation affect allele frequencies in a population?

It introduces new alleles, altering the existing frequencies.

What happens to allele frequencies during genetic drift?

They can fluctuate randomly, especially in small populations.

What are phenocopies?

Traits that mimic genetic disorders but are caused by environmental factors.

What is the purpose of risk estimation in genetic counselling?

To inform families about their risk of passing on genetic disorders.

How is the risk of inheritance for an autosomal dominant trait communicated to families?

Through clear communication of a 50% risk for each offspring.

What is the definition of a carrier in genetics?

An individual who has one copy of a recessive allele that does not manifest the trait.