GENETIC PREDISPOSITION

Question 1

FAMILY STUDIES

Answer 1

• evidence to show clinically diagnosed ASD runs families
• szatmari combined the data from several family studies to calculate overall sibling risk which was 2.2% considering chances of having autism is 0.11% a sibling is 20 times as likely to develop it

Question 2

TWIN STUDIES

Answer 2

• Bailey et al analysed British twin study data and concordance rate for MZ twins was 60% but 0% for DZ twins when looking at a wider definition found 92% concordance for MZ and 10% for DZ

Question 3

SIMPLEX AND MULTIPLEX

Answer 3

• Bernier et al realised that families affected by ASD differ in a significant way such as in some cases only one family member has ASD (simplex) and multiplex have have more than one member whether diagnosed or not
• could mean ASD is more likely caused by genetic variations that are inherited
• genetic causes of simplex known as de novo which is new genetic mutations that occur when sequences of DNA or duplicated or duplicated mutation is replicated across all cells an account for 10% of all diagnosed cases of ASD more likely to happen when parents are older

Question 4

SYNDROMIC & NON-SYNDROMIC

Answer 4

• ASD can be non-syndromic where the disorder is the main or only one diagnosed unclear what genetically causes this
• can be syndromic such as accompanies another condition one that is the main disorder
• importance of this is other condition may have a genetic cause
• eg fragile X syndrome (FXS) symptoms include a range of intellectual Disabilities and distinct facial features caused by the FMR1 gene mutation on X chromosome
• zingerevich found 60% of individuals with FXS also meet criteria for ASD