• Analyse a family tree to identify mode of inheritance

is it present in every generation ? - if yes then autosomal dominant - if no = autosomal recessive

is it sex linked

is it mitochondrial linked

• Discriminate between locus heterogeneity and allelic heterogeneity

Allelic heterogeneity refers to instances where mutations in different alleles at the same locus produce the same disease. By contrast, locus heterogeneity describes mutations in different genes whereby any one mutation generates the same disorde

so basically

Allelic heterogeneity = MUTATIONS in different allels at the same locus causing the same pathology/disease

Locus heterogeneity = MUTATIONS in different genes whereby they cause the same pathology/disease

• Give examples of disorders arising from changes in gene dosage

DiGeorges syndrome

• Define genetic penetrance

the proportion of people with a particular genetic variant (or gene mutation) who exhibit signs and symptoms of a genetic disorder. If some people with the variant do not develop features of the disorder, the condition is said to have reduced (or incomplete) penetrance.