BMS2042 - W1: Introduction to Genetic Inheritence

Define the following: Trait, phenotype, genotype, locus

Trait: Characteristic of an organism (e.g. seed colour)

phenotype: Appearance of an organism (e.g. Yellow seeds)

Genotype: Genetic composition of an organism (e.g. YY)

Locus: specific place on a chromosome occupied by a gene

What is monogenic (Mendelian) vs polygenic?

Monogenic: involves one gene

Polygenic: involves many genes

What is the principle of uniformity?

The traits do not blend. The phenotype is either one or the other. (Not the case for all genes)

What is the principle of independent assortment?

Alleles coding for different traits separate independently.

• relates to two or more genes

• random independent assortment between alleles

Define proband and consultand

Proband: an affected individual who first brings a family's genetic condition to the attention of a healthcare professional

Consultand: an individual seeking genetic evaluation

• They may be unaffected (e.g. sibling, child)

• Commonly, the consultand is also the proband but not always

Autosomal recessive disorders:

• relates to a gene on one of the 22 autosomes

• phenotype only expressed in homozygous

• typically loss of function variants

• increased incidents in parental consanguinity

• tends to skip generations

what is consanguinity?

People having the child are related

(inbred, incest - idk if these are bad terms or not)

• increases chance that mating couple carries same disease causing variant

Dominant inheritance:

Affected person usually has at least 1 affected parent

• can affect either sex

• one affected one unaffected parent = child has 50% chance of being affected

Autosomal Dominant

• Mostly doesn’t skip generations

• similar number of affected males and females

• male passes to both males and females

• affected children born to affected parents