A/50 Flashcards
What are 5 examples of AR disorders
- CF
- Phenylketonuria
- Tay-sachs disease
- alpha and beta thalassemias
- Sickle cell anemia
What is the abnormal protein in phenylketonuria?
lack of phenylalanine hydroxylase enzyme
What is the abnormal protein in Tay Sachs disease?
hexosaminidase beta subunit
What is the prevalence of phenylketonuria?
1 / 10 000
Signs of phenylketonuria (5)
- increasing serum phenylalanine levels after 1-2 weeks
- mental retardation
- seizures
- neurological abnormalities
- decreased skin pigmentation
How can PKU be avoided?
By restricting consumption of phenylalanine (milk, eggs, chicken)
What is the biochemical explanation for PKU?
Without enzyme, cannot convert phenylalanine to tyrosine, so it produces many intermediates from other pathways
Why is there light pigmentation in PKU?
Because tyrosine is a melanin precursor
What is the prevalence of galactosemia?
1 / 60 000
What enzyme is missing in galactosemia?
GALT (galactose 1 phosphate uridyltransferase)
Result of missing enzyme in galactosemia?
Galactose 1P accumulation in all tissues
Anatomical changes in galactosemia
- early onset hepatomegaly
- jaundice
- cirrhosis
- cataracts
- loss of nerve cells
How to treat galactosemia?
Removing galactose from the diet for the first 2 years of life
What does the lack of enzyme cause in Tay Sachs disease?
Gangliosidosis : accumulation of gangliosides
Which cells are the most affected in Tay Sachs disease?
CNS cells : neurons, axons, glial cells
What happens to the cells in Tay Sachs disease?
they become swollen / foamy
What are the symptoms of Tay Sachs disease?
- mental retardation
- blindness
- motor weakness
- death by 2/3
4 types of glycogen storage diseases
- Hepatic type (e.g : type 1, Vongierke)
- Myopathic type (e.g type 5, McArdle’s)
- Miscellaneous type (e.g type 2, Pompe)
3 examples of X-linked disorders
- Hemophilia A
- Duchenne muscular distrophy
- Fragile X syndrome
Abnormal protein in hemophilia A
Factor VIII
Abnormal protein ini duchenne muscular distrophy
Dystrophin
What is the genetic issue in fragile X syndrome?
upwards of 4000 tandem repeats of CGG in the FMR1 gene
Anatomical changes in fragile X syndrome (3)
- mental retardation
- macroorchidism
- abnormal facial features
