7 - Genetic and Pediatric Disease (Exam 2) Flashcards
What are the three major categories of human disease determined by?
- Environmental factors
- Genetics
- Combination of environmental factors and genetics
Are humans diploid or haploid, and what does that mean?
Diploid
Have pairs of each chromosome
How many pairs of chromosomes do humans have, and what is the total number of chromosomes?
23 pairs of chromosomes
46 total chromosomes
What is karyotyping?
The study of number, size and shape of somatic chromosomes
How many pairs of autosomes do humans have?
22 pairs
How many pairs of sex chromosomes do humans have?
1 pair
What do the sex chromosomes of a female present as?
XX
What do the sex chromosomes of a male present as?
XY
What percent of newborns possess a gross (physical) chromosomal abnormality?
1%
About what percent of pregnancies end in miscarriage?
33%
What are mutations?
Permanent changes in DNA structure
What are the two major types of mutations?
- Genome mutations
2. Chromosome mutations
What are two types of genome mutations?
- Point mutations
2. Frameshift mutations
What are point mutations?
Substitution of a single nucleotide
What are frameshift mutations, and what do they cause?
Insertion/deletion of one or two base pairs of an allele
Cause alteration in reading frame of DNA
How do chromosome mutations differ from genome mutations, and how do they occur?
Usually numerical errors (chromosome compliment not a multiple of 23) resulting from faulty disjunction during meiosis
Results in extra chromosome/ extra copy of genes
Example: Down’s syndrome - trisomy 21
What is aneuploidy?
Numerical errors in chromosomes
What is of primary importance with chromosomal aberrations?
Karyotype analysis
With sex chromosome aberration, most traits are lethal. What is frequent in survivors?
Mental retardation
Do sex chromosome aberrations typically have a family history?
No
Therefore pedigree analysis is difficult and not practical
What are 3 categories of genetic disease?
- Single gene inheritance
- Multifactorial or polygenic inheritance
- Chromosomal aberrations/ cytogenic disorders
What are individuals with single gene inheritance carriers of?
5-8 deleterious genes
What are the majority (80-85%) of single gene inheritances?
Familial
What are the 4 patterns of single gene inheritance?
- Autosomal dominant
- Autosomal recessive
- X-linked dominant
- X-linked recessive
What are X-linked chromosome related disorders also known as?
Sex linked chromosome related disorders