Molecular Basis of Disease Flashcards
What kind of mutation results in a product with a reduced or ablated function?
Loss of function mutation
What kind of mutation results in a product with a new and abnormal function?
Gain of function mutation
What type of mutation replaces one amino acid with another in the same gene product?
Missense mutation
What kind of mutation replaces an amino acid with a stop codon?
Nonsense mutation
What kind of mutation results in production of a trunated protein?
Nonsense mutation
What type of mutation is produced by deletions, insertions or splicing errors?
Frameshift mutations
What kind of mutations create or destroy splice donor or acceptor sites? What are the splicing possibilities following the mutation?
Splice Site mutations; Can either leave in the intron or could splice out an exon
What type of mutation chaneges the codon but does not alter the amino acid encoded?
Silent mutation
What are dynamic mutations?
Tandem repeats that expand in size
What is the trinucleotide expanded in myotonic dystrophy?
CTG
What does Arg117His mean with regard to mutation?
Arginine 117 was replaced with a histidine
What does G.1162G->A mean?
Genomic guanine 1162 replaced by adenine
What does F508del mean?
deletion of phenylalanine #508
What are modifier genes?
Genes that can alter the phenotype associated with a mutation
What is a compound heterozygote?
An individual with one allele that has one mutation and another allele that has a different mutation in the same gene
What is the enzyme defect in PKU?
Phenylalanine hydrogenase
What is the enzyme defect in galactosemia?
g-1-uridyl transferase
What is the enzyme defect in Tay-Sachs?
Hexominidase A
What is the enzyme defect in Lesch-Nyan syndrome?
Hypoxanthine-guanine phosphoribosyltransferase
Generally, what is the moe of inheritance for enzyme defects?
Autosomal recessive
What is the mode of inheritance for phenylketonuria?
Autosomal recessive
What molecule accumulates in PKU?
Phenylalanine
What is the treatment for PKU?
Dietary restriction of phenylalaine
What is the significance of maternal PKU?
Women with PKU that are not on the restictive diet when they are pregnant can have offspring with developmental problems due to the teratogenic effect of high levels of phenylalanine
At what age do symptoms of Tay-Sachs begin to appear?
6 months
What product accumulates in Tay-Sachs?
Ganglioside GM2
What are the symptoms of Tay-Sachs?
Seizures, behavioral changes, feeding difficulties, cherry red macula, abnormal body tone, motor skill loss, blindness, deafness, intellectual disability
What is the mode of inheritance for albinisim? What is the ezyme defect?
Autosomal recessive; tyrosinase
Lack of development of which prt of the retina results in visual acuity problems in individuals with albinism?
The fovea
Mutation in what molecule is the basis of familial hypercholesterolemia?
The LDL receptor
What physical symtoms is classic for familial hypercholesterolemia?
Cholesterol xanthomas
What is the mode of inheritance for familial hypercholesterolemia?
Autosomal dominant
What transport protein is defective in cystic fibrosis?
Cystic fibrosis transmembrane regulator (CFTR) (chloride ion channel)
What is the mode of inheritance for Osteogenesis Imperfecta?
Autosomal dominant
What gene is mutated in osteogenesis imperfecta?
Type I collagen gene
What is the mode of inheritance for Thalassemia?
Autosomal recessive
What genes are mutated in thalassemia?
either alpha globin or beta globin
What physical symptom is commonly seen in individuals with thalassemia?
Marked hepatosplenomegaly
