Week 6 Clinical Genetics Flashcards
How many DNA units are in the human genome?
Approximately 3.4 billion base pairs.
What is the challenge in detecting all mutation types using genome/exome sequencing?
Some mutations are hard to detect due to low allele frequency or complex nature.
What is autosomal dominant inheritance?
One affected parent; affects both genders; 50% chance of inheritance.
Give an example of an autosomal dominant disorder.
Huntington’s disease.
What is autosomal recessive inheritance?
Parents are carriers; both genders affected; 25% chance of inheritance if both parents are carriers.
Give examples of autosomal recessive disorders.
Cystic fibrosis, sickle-cell anemia.
What is X-linked recessive inheritance?
Mostly affects males; inherited from carrier mothers; no male-to-male transmission.
Give examples of X-linked recessive disorders.
Haemophilia, red-green colour blindness.
What is X-linked dominant inheritance?
More females affected; all daughters of affected males are affected, no sons; affected females have 50% risk of passing it on.
Give examples of X-linked dominant disorders.
Rett syndrome, Incontinentia Pigmenti.
What is Y-linked inheritance?
Only males affected; passed from father to all sons; no daughters affected.
Give examples of Y-linked traits or conditions.
Male infertility and male-specific traits (though not all are confirmed).
What causes Down’s Syndrome?
Trisomy 21 – an extra copy of chromosome 21.
What causes Patau Syndrome?
Trisomy 13 – an extra copy of chromosome 13.
What causes Edwards Syndrome?
Trisomy 18 – an extra copy of chromosome 18.
