Congenital and genetic disorders

Monogenic

Problem with one defective gene (Autosomal dominant or Recessive)

Autosomal dominant (monogenic)

either sex has 50% chance of being affected One defective gene but is dominant

gene + environment =

environment has affect on genes

congenital abnormalities; what are teratogens?

external factors to fetus environmental (also maternal) factors causing birth defects e.g. thalidomide (tx morning sickness caused limb defects There is a critical period when this is most likely to occur.

Genetics and environmental in complex traits

genetic predisposition + environmental predisposition (smoking)

What is a genotype?

The genetic information stored in the base sequence triplet code (AGT) (not always detectable) (Bb) genes from both parents although one dominant trait is expressed (visible=brown eyes)

Heterozygous

The genetics term heterozygous refers to a pair of genes where one is dominant and one is recessive — they're different. One gene from dad is different (allele is coded differently) from the gene of your mom.

Genotype

The genotype refers to the entire set of genes in a cell, an organism, or an individual. A gene for a particular character or trait may exist in two allelic forms; one is dominant (e.g. A) and the other is recessive (e.g. a). Based on this, there could be three possible genotypes for a particular character: AA (homozygous dominant), Aa (heterozygous), and aa (homozygous recessive).

Insertion (gene) mutations are?

is the addition of one or more nucleotide base pairs into a DNA sequence.

Phenotype

is the composite of an organism's observable characteristics or traits,

The mito gene defects cause?

neuromuscular defects.

Allele

one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.A specific version of a gene.

Inversion

requires 2 breaks in single chromosome (happen for ex by X-ray radiation), with inversion to the opposite side if the centromere

4 types of genetic abnormalities

1) Monogenic (problems with 1 defective gene) -autosomal dominant -autosomal recessive -x-linked recessive 2)Mitichondrial gene 3) complex trait 4) Chromosomal (# and structure)

Central nervous system is developing when?

2-4.5 weeks

Heart is developing when?

2.25-5.75 weeks

Extremities and Eyes are developing when

3.5- 7 3.5 -7.5

How many mito genes? and what do they code for?

37 respiratory chain (enzymes affected d/t defected genes) Maternal inheritance because mitochondria DNA is passed down from the mother. Mitochondria in the sperm is highly condensed in the flagella which falls off once it is implanted therefore the maternal Mitogenes are inherited.

External genitalia is developing when?

6.5-8.5 weeks

Duplication

A segment breaks off and the piece attaches to the other homogenous chromosome (deletion on other chromosome also takes place)

What are congenital abnormalities?

Any defects present @ birth d/t developmental errors during gestation.

Autosomal recessive

Autosomal recessive is one of several ways that a trait, disorder, or disease can be passed down through families. An autosomal recessive disorder means two copies of an abnormal gene must be present in order for the disease or trait to develop.

Sensitivity to teratogenic agents is at its critical period when?

During the first 8 weeks

Autosomal recessive (monogenic)

Either sex has chance of being affected one defective gene but is recessive 25% affected 50% carriers 25% unaffected

Turners syndrome

Females X missing second X

Homozygous

If you're homozygous, you've got a pair of matching alleles, which are the two genes that control a particular trait. (allele is coded the same, identical alleles)

Autosomal dominant

In an autosomal dominant disease, if you inherit the abnormal gene from only one parent, you can get the disease. Often, one of the parents may also have the disease. 50% chance of inheriting

Structural defects

Inversion translocation deletion

What is meant by vulnerability?

It is a specie time period during development when each organ is most likely developing = vulnerable at that time. Some disruption to fetuses external environment During organogenesis 15-60 days post conception (aprox 2 months)

Kinefetters syndrome

Males XXY trisomy

Complex traits are influenced by:

More that one factor genetic or environmental

deletion (gene) mutation are?

One base pair is deleted from the DNA

Autosomal

Refers to any of the chromosomes other than the sex-determining chromosomes (i.e., the X and Y) or the genes on these chromosomes. Traits other than sex traits

Congenital abnormalities dev d/t ?

Vulnerability, Critical period, Teratogens

Substitution (gene) mutations are?

When one base is changed to another base (A G T C) = changes protein that is created.

Translocation

a section of a homogenous pair breaks off and attaches to a different chromosome pair that is not homogenous to the other pair. segment attaches to non- homogenous pair.

Deletion

a segment of the chromosome breaks off (d/t e.g. radiation) but does not attach its self again)

Numerical abnormalities in chromosomes:

aneuploidy (extra or missing chromosome) trisomy (extra chromosome in pair) monosomy (missing chromosome in pair)

X-linked recessive (monogenic)

sex chromosomes affected = problem Female with defective x recessive = 50% chance males affected and %50 chance famales affected. Males who are defective x recessive carriers pass down to females only.

What is the critical period?

specific times for each organ (when it is developing) that they are most likely affected. (brain is exception d/t extended dev period)

What is a phenotype?

the recognizable traits associated with a genotype. Expressed traits. The dominant gene (allele in the Genotype= expressed trait= brown eyes)