Genetic Conditions Flashcards
What gene is affected in CF?
CFTR gene on chromosome 7
How does the genetic fault cause the symptoms seen in CF?
CFTR gene codes for a faulty chloride ion channel, the reduced functionality of the channel causes a build up of mucus in the airways.
Haemophilia A is linked to which chromosome, and what does this mean for its presentation in genders?
X, meaning women are mostly unaffected because they would have another version of the X chromosome with a “normal” gene.
What gene does Haemophilia A affect?
Factor VIII gene
People with Haemophilia A should avoid which common drug class?
NSAIDs
What is the current estimate of the incidence of CF in Western Europe?
1/4500
Which ethnicity is CF more prevalent in?
Caucasian
Phenylketonuria is an autosomal “what” disorder?
recessive
Name a Y-linked disorder?
Webbed toes
Name two X-linked disorders
Haemophilia A and Red-Green colour blindness
Sickle cell anaemia affects what structure, and what effect does this have on the function of this structure?
The shape of haemoglobin creates “sickle shaped” red blood cells, this reduces their ability to carry oxygen and can also cause them to get stuck in capillaries.
Familial hypercholesterolemia is autosomal “what”?
Dominant
What gene is affected in familial hypercholesterolemia?
Low Density lipoprotein receptor (LDLR)
What does phenylalanine hydroxylase do, and why is it important?
Converts phenylalanine from our digested food into tyrosine. Tyrosine is important in thyroid hormone production and overall metabolism in the body. This affects development and cognitive function.
PKU is an autosomal recessive disorder, what probability is there of affected offspring if their parents are both carriers?
25%
What is aneuploidy?
Higher or lower numbers of chromosomes
What are the most common chromosomal abnormalities?
Deletion, translocation, inversion and duplication
The genetic disorder PKU affects the production of what enzyme?
Phenylalanine hydroxylase
How common is PKU in the UK?
1/10,000
Roughly how many inborn errors of metabolism are there?
Over 200
Without treatment, what is the life expectancy of homozygous familial hypercholesterolemia?
Less than 20 years
Familial hypercholesterolemia occurs in how many people in the UK?
1 in 250
What type of congenital genetic disease is Down’s Syndrome?
Spontaneous
What genetic error is Down Syndrome (trisomy) caused by?
An extra copy of chromosome 21
95% of Down Syndrome cases are caused by what, and what is it?
Nondisjunction, the spindle fibres fail to separate the sister chromatids in either step one or two of meiosis, creating some gametes with a missing chromosome and some cells with an extra chromosome.
Apart from nondisjunction, what are the other two genetic error processes that can cause Down Syndrome?
Robertsonian translocation where parts of two chromosomes switch, creating lost or copied genetic material (4%) and mosaic where an error in mitosis creates a mixture of cells with normal amount of chromosomes and some with an extra chromosome (1%)
What effects can Down Syndrome have on the heart?
Increased risk of septal defects
What is the most common risk factor for down syndrome?
Maternal age
