Autosomal Abnormalities:
Most of the human chromosomal abnormalities appear in the autosomes. Many of these abnormalities are monosomies or trisomies. All fetuses with autosomal monosomies abort early in pregnancy, and those with autosomal trisomies mostly and sadly die before birth, and the survivors are faced with physical malformations, mental retardation, and short lives.
The most well known autosomal abnormality is the dreaded Down Syndrome. People with this abnormality have an extra chromosome. This was discovered in 1959, and scientists are currently working on the genes that are responsible for the extra chromosome, some think there may be up to 650 genes that are the reason for Down Syndrome.
People with Down Syndrome have short, stocky bodies with thicker hands and feet. They also have broad, short heads with low-set ears small concave saddle-shaped or flattened noses, relatively large ridged tongues, loose joints, and low muscle tone that leads to poor motion skills. Thier eyes have an East-Asian like appearance because of an epicanthic fold.
People with Down Syndrome frequently have other medical problems, such as epilepsy, hypothyroidism, crossed eyes, near-sightedness or far-sightedness, hearing impairment that makes it difficult to process auditory information, heart defects, intestinal malformations, hernias, sometimes respiratory infections, (like pneumonia), and childhood leukemia is 20x as common than average for them.
Individuals with Down Syndrome age at a faster rate. By age 35, at least 25% of those who have non-mosaic Down Syndrome have begun to develop Alzheimer’s. However, this was not a problem in the early 1900’s because most patients with this horrible abnormality died in their childhood. The life expectancy for a child with Down Syndrome in 1929 was a mere 9 years. In 1980, it was still very low at 25. Due to the better medicine and treatments for those with Down Syndrome, patients in America and other well-developed countries can live up to 50, maybe even 60. Sadly, around half of South African babies with Down Syndrome die within their first year of life.
The worst trait about Down Syndrome is mental retardation. Remember, not all people with mental retardation have this syndrome. They will only reach the mental age level of a 3-7 year old, and they are quite slow learners. The most high-achieving people with Down Syndrome can reach the mental capacity of the average 12 year old. People with Down Syndrome have gentle, trusting personalities and are very warm and loving.
Most fetuses with Down Syndrome (around 85%) die before birth. It is likely that 25% of these miscarriages are due to the trisomy form of Down Syndrome. However, over 400,000 people with Down Syndrome in the U.S. have survived and are alive today. Around 1 out of every 800 births is a child with Down Syndrome. This is the case for the common trisomy form of Down Syndrome, not the rare translocational form. Women who are 20 years old have the lowest chance (1 in 2000) of having a Down Syndrome baby. Women do not reach the average risk rate of 1 in 800 until they reach the age of 30.
It seems as mothers who are older produce more Down Syndrome babies, however this is not the case. Remember that older women are less likely to have children. In the U.S., 80% of Down Syndrome children are born to women under 35. The majority of women giving birth to Down Syndrome babies are still in their 20’s. Only .3% of all births in the U.S. are to mothers 45 and older.
There is some increase in the risk of Down Syndrome children being conceived when the father is older. However, little data are available to support this. Only 5% of all Down Syndrome children are the result of defective sperm. Sperm are less likely to give the syndrome then the ova, probably because the entire male Meiosis process takes 74 hours, which gives less time for the sperm to become defective.
Women who have a Down Syndrome baby are more likely to have another one. Women with Down Syndrome also have a higher risk of having children with this condition, as half their offspring would be expected to inherit it. However, many affected fetuses are lost in miscarriages. Apparently, Down Syndrome men can father a child though it is very rare- there has only been one documented instance of it.
The most well known autosomal abnormality is the dreaded Down Syndrome. People with this abnormality have an extra chromosome. This was discovered in 1959, and scientists are currently working on the genes that are responsible for the extra chromosome, some think there may be up to 650 genes that are the reason for Down Syndrome.
People with Down Syndrome have short, stocky bodies with thicker hands and feet. They also have broad, short heads with low-set ears small concave saddle-shaped or flattened noses, relatively large ridged tongues, loose joints, and low muscle tone that leads to poor motion skills. Thier eyes have an East-Asian like appearance because of an epicanthic fold.
People with Down Syndrome frequently have other medical problems, such as epilepsy, hypothyroidism, crossed eyes, near-sightedness or far-sightedness, hearing impairment that makes it difficult to process auditory information, heart defects, intestinal malformations, hernias, sometimes respiratory infections, (like pneumonia), and childhood leukemia is 20x as common than average for them.
Individuals with Down Syndrome age at a faster rate. By age 35, at least 25% of those who have non-mosaic Down Syndrome have begun to develop Alzheimer’s. However, this was not a problem in the early 1900’s because most patients with this horrible abnormality died in their childhood. The life expectancy for a child with Down Syndrome in 1929 was a mere 9 years. In 1980, it was still very low at 25. Due to the better medicine and treatments for those with Down Syndrome, patients in America and other well-developed countries can live up to 50, maybe even 60. Sadly, around half of South African babies with Down Syndrome die within their first year of life.
The worst trait about Down Syndrome is mental retardation. Remember, not all people with mental retardation have this syndrome. They will only reach the mental age level of a 3-7 year old, and they are quite slow learners. The most high-achieving people with Down Syndrome can reach the mental capacity of the average 12 year old. People with Down Syndrome have gentle, trusting personalities and are very warm and loving.
Most fetuses with Down Syndrome (around 85%) die before birth. It is likely that 25% of these miscarriages are due to the trisomy form of Down Syndrome. However, over 400,000 people with Down Syndrome in the U.S. have survived and are alive today. Around 1 out of every 800 births is a child with Down Syndrome. This is the case for the common trisomy form of Down Syndrome, not the rare translocational form. Women who are 20 years old have the lowest chance (1 in 2000) of having a Down Syndrome baby. Women do not reach the average risk rate of 1 in 800 until they reach the age of 30.
It seems as mothers who are older produce more Down Syndrome babies, however this is not the case. Remember that older women are less likely to have children. In the U.S., 80% of Down Syndrome children are born to women under 35. The majority of women giving birth to Down Syndrome babies are still in their 20’s. Only .3% of all births in the U.S. are to mothers 45 and older.
There is some increase in the risk of Down Syndrome children being conceived when the father is older. However, little data are available to support this. Only 5% of all Down Syndrome children are the result of defective sperm. Sperm are less likely to give the syndrome then the ova, probably because the entire male Meiosis process takes 74 hours, which gives less time for the sperm to become defective.
Women who have a Down Syndrome baby are more likely to have another one. Women with Down Syndrome also have a higher risk of having children with this condition, as half their offspring would be expected to inherit it. However, many affected fetuses are lost in miscarriages. Apparently, Down Syndrome men can father a child though it is very rare- there has only been one documented instance of it.