Please enable JavaScript.
Coggle requires JavaScript to display documents.
บทที่ 8 Medical genetics - Coggle Diagram
บทที่ 8 Medical genetics
Mutations in single genes
Point mutations in coding sequences
Missense mutation: yield a different amino acid
Nonsense mutation: formation of an inappropriate “stop” codon
Mutations within noncoding regions
Enhancer or promoter regions
Defective splicing
Deletions and insertions
Frameshift mutations
alter the reading frame of the DNA
Trinucleotide repeat mutations
Amplification of triple-nucleotide sequences
Mendelian disorders
Mutations in single genes that have a large effect
Mendelian traits: dominant, recessive, or codominant
Penetrance
The percentage of individuals who carry a gene and express the trait
Variable expressivity
Variation in the degree or severity of the effect caused by a mutation
Pleiotropism
Multiple possible end effects of a mutant gene
Genetic heterogeneity
Multiple different mutations leading to the same outcome
single gene disorders
Autosomal dominant (AD)
Vertical transmission
Occurances
Male = female
Recurrent risk in transmission: 50%
Clinical features modified by penetrance and expressivity
Clinical onset later than in AR disorders
Autosomal recessive (AR)
Horizontal transmission
Occurrences
Recurrent risk in transmission = 25%
Male = female
Father and mother = obligate carriers
More uniform expression
Early onset in life
X-linked
All sex-linked disorders = X-linked
Most X-linked disorders = recessive
Fully expressed in males (hemizygous)
Not expressed in females
chromosomal disorders
Numerical abnormalities (most common)
Polyploidy
aneuploidy (common)
Structural abnormalities
Deletion
Translocation
Isochromosome
Inversion
Ring chromosome