Learning Objectives

• Explain the difference between mitochondrial inheritance and autosomal inheritance
• Describe the impact of mutations on the X-chromosomes in the different sexes
• Recognise and recall the cause and clinical features of mitochondrial and X-linked disorders
• Extrapolate from a family pedigree whether a family is affected by a Xlinked or mitochondrial disorder
• Explain to a patient how mitochondrial and X-linked disorders are inherited using appropriate language

Sex-Linked Inheritance

• what are sex-linked traits?
• what are sex-limited traits?
• what are sex-influenced traits?
• how do males and females express X-linked traits?
• what are the features of X-linked dominant inheritance?
• what are the features of X-linked recessive inheritance?

Colour Blindness

• what 2 genes encode opsins (pigment proteins)?
• is this trait dominant or recessive?
• incidence for males vs females?
• what genetic defect causes this?

Hypophosphatemic Rickets