Genetic Disorders Flashcards
Genetic
Defects caused by genes (Ex. Trisomy 21)
Congenital
Defects present at birth
Hereditary
Defects passed from one generation to the next through genes (Ex. Hemophilia )
XX produces …
A female
XY produces ….
A male
There are 3 major types of monogenic disorders ( Disorders caused by 1 gene)
- Autosomal recessive (Cystic Fibrosis, Sickle Cell Anemia)
- Autosomal dominant ( BRCA 1, BRCA 2, Marfan Syndrome, Huntington Chorea)
- X or sex- linked ( Color Blind, Hemophilia, Duchene muscular dystrophy)
Autosomal Recessive
For an autosomal recessive gene to be expressed the individual must carry a pair of the genes. Ex. Cystic Fibrosis, Sickle cell anemia
Autosomal Dominate
- You only need to get the abnormal gene from one parent in order for you to inherit the disease
What is dominant inheritance means
An abnormal gene from one parent is capable of causing disease even though the matching gene from the other parent is normal. The abnormal gene “dominates” the pair of genes.
Autosomal dominate. If two carriers of a dominate gene produce offspring…
3 out of 4 (75%) of the offspring carry the gene and may express the trait.
X- linked recessive
- Sex-linked diseases are inherited through one of the “sex chromosomes” - the X or Y chromosomes.
- Normally, an individual would need to inherit 2 recessive genes for the disease to be expressed.
- The gene on the Y chromosome does not exert an influence over the X.
- The gene on the X chromosome is allowed to exert its influence.
- The woman is usually the carrier and her sons will have a 50% of inheriting the disease.
Hereditary disorders are subset of…
Chromosomal disorders
Penetrance
The proportion of individuals carrying a particular variation of a gene that also express an associated trait.
What is multi-factorial disorders:
Congenital disorders that have a combinations of causes.
Congenital anomalies:
- Structural defects present at birth
2. Congenital anomalies may be inherited or sporadic, isolated or multiple, apparent or hidden, gross or microscopic.
Down Syndrome D/S
The most commonly inherited chromosomal disorder. Characterized:
- Hypotonia
- Cognitive delay
- Abnormal facial features
- Distinctive physical abnormalities
- Developmental delay
- The incidence rises with maternal and paternal age.