1. GENETICALLY TRANSMITTED DISEASES
What are genetically transmitted diseases? Human beings are born with different characteristic such as skin color, tall-short, fat-skinny, curly, or straight hair, and intellectual level. These characteristics are controlled or determined by the genes transmitted from their parents. If there are any abnormalities hidden in the genes such as disabilities or disease, these abnormal characteristics will be transmitted to their children. We call these genetically transmitted diseases. The abnormalities hidden in the genes of their parents may come from their ancestors or from a mutation of the gene. These are cells which have been changed. This can happen from such factors as receiving radiation or from some types of chemical substances.
The abnormalities which can be transmitted from the genes occur in both sexes. Some are transmitted only to males and others only to females. This is controlled by the dominant or recessive genes of the human chromosome.
What is a chromosome?
Chromosomes are an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes. The abnormality of chromosomes will create an imbalance in the genes. If there is much abnormality or imbalance while getting pregnant, the infant might be proportionality or dead after delivery. If there is not too much abnormality, the infant may survive but may be handicapped or have low intelligence, etc.
There are 22 pairs or 44 bars of chromosome in our body. These can be divided into two types which are:
- Autosome is the body chromosome which consists 22 pairs or 44 bars.
- Sex Chromosome is composed of 1 pair or 2 bars.
- Female chromosomes will be XX type.
- Male chromosomes will be XY type.
Abnormalities Transmitted from the Genes in the body Chromosome (Autosome)
- Occur equally to both sexes.
- Characteristics which are controlled by the recessive genes include thalassemia, albinism, and sickle red blood cells.
- Characteristics which are controlled by the dominant gene include neurofibromatosis, short fingers, and dwarfism. Abnormalities Transmitted from the Genes in the sex chromosome.
- Occur to both sexes but can be more in either of the sexes.
- Characteristics which are controlled by recessive genes on the chromosome X are baldheadedness, color blindness, disease decreased enzyme – G-6-PD, muscular dystrophy, being gay is controlled by a recessive gene on chromosome X which can occur more in males than in females (one X gene of male)
How severe is the abnormality of the genes or the genetic disease?
1. Severe enough to cause death since the infants are in the womb and they lack water due to some of blood diseases.
2. Not dead immediately but they may die afterward from the muscular atrophy.
3. Low intelligence, handicapped, and cannot help themselves such as the down syndrome groups.
4. Not severe but may have trouble for daily living such as color blindness.
Examples of genetic abnormality which are commonly found are the down syndrome groups, muscular atrophy disease, and some types of leukemia.
Can we prevent genetic abnormality in infants?
Some of the genetic abnormalities can be detected in early pregnancy by examining the abnormality of the chromosomes and screening the parents for thalassemia, and whether they are carriers of any disease or not.
When any abnormality is found, consult a physician who is specialist in that disease to help plan for safe pregnancy.
When should I have chromosome analysis?
1. Before making decision to have a child, couples should have a screen to check the heredity and find if there is a risk factor.
2. In the case of infertility, frequent abortion, a child has died after delivery, disordered by birth, or retarded child.
3. pregnant women who are over 35 years of age.
4. In the case of receiving radiation or any toxin which might affect the chromosome.
5. In case there is already a child showing any abnormality after delivery or retardation.
How else can we check for chromosome abnormality?
Checking the chromosome for abnormality can be done by:
1. blood
2. cells in the amniotic fluid
3. infant cells
4. marrow cells
5. other cells