Back to the full dot-point answer
NSWBiologyQuick questions
Module 8: Non-infectious Disease and Disorders
Quick questions on Genetic disorders: cystic fibrosis, sickle cell, Huntington's: HSC Biology Module 8
8short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What are pedigree analysis for these conditions?Show answer
Autosomal recessive pedigree (cystic fibrosis, sickle cell).
What is gene and mutation?Show answer
CFTR (cystic fibrosis transmembrane conductance regulator), chromosome 7. The most common mutation is , a three-base-pair deletion that removes phenylalanine at position 508 of the CFTR protein.
What is inheritance?Show answer
Autosomal recessive. Two unaffected carrier parents () have a 25 percent chance of an affected child. Carrier frequency in Australians of Northern European ancestry is approximately 1 in 25.
What is pathophysiology?Show answer
CFTR is a chloride channel in the apical membrane of epithelial cells. Loss of function reduces chloride and water secretion onto epithelial surfaces, producing thick viscous mucus. The mucus obstructs:
What is treatment?Show answer
Airway clearance physiotherapy, inhaled antibiotics, pancreatic enzyme replacement, high-calorie diet, and CFTR modulator drugs (e.g. ivacaftor for G551D, elexacaftor/tezacaftor/ivacaftor for ). Lung transplant for end-stage disease.
What is q1?Show answer
Identify the inheritance pattern and chromosome location of (a) cystic fibrosis, (b) sickle cell anaemia, (c) Huntington's disease. [3 marks]
What is q2?Show answer
Two heterozygous CFTR carriers (Aa) have three children. Calculate (a) the probability that all three are unaffected, (b) the probability that at least one is affected. [3 marks]
What is q3?Show answer
Compare the molecular and clinical features of cystic fibrosis and Huntington's disease. (a) Identify the gene and mutation type for each. (b) Describe the typical age of symptom onset.