SEX LINKED DISEASES

PRE IMPLANTATION SCREENING FOR SEX SELECTION
Pre implantation screening for sex selection is a scientific technology used to identify genetic defects in embryos created through in vitro-fertilization (IVF) cycles.
This procedure is necessary where both or one of the parents of a child (embryo) has a known genetic abnormality.However, this treatment is also used to diagnose fertility problems.
IVF has been used to reduce the number of children born with inherited diseases. So far it has recorded a 99% success rate.Sex linked diseases affect more males than females.Consequently,to avoid it, couples giving birth to boys with the disease have to find a way of giving birth to girls. With this technology, the doctor is able to make this happen by selecting the embryos without the affected sex chromosomes leading to the birth of a healthy child. This technology can also be used to assist couples with only boys or girls, to give birth to girls and boys respectively through the selection of embryos with the female XX chromosomes or male XY chromosomes.
Sex linked diseases are those inherited through one of the sex chromosomes, in most cases the X chromosome. There are two forms of sex linked diseases:X linked recessive diseases and X linked dominant diseases. The most common sex linked diseases are:Haemophilia –an individual has a problem with blood clotting.Duchenne-a muscular dystrophy i.e. muscle degenerative disease.
Females have the XX chromosomes and males have the XY chromosomes. A child inherits one chromosome from each parent, with the mother giving the chromosome and the father giving either the X or Y chromosome. If the father‘s fertilizing sperm carries the X chromosome, it’ll unite with the mother’s X chromosome to result in the XX pair ,which is a girl. If the father’s fertilizing sperm carries the Y chromosome, the resulting combination brings forth a boy. This means that it’s the man’s sex chromosome that determines a child’s gender.
An abnormality on the X chromosome of the mother results in a genetic related disease in the boy and not the girl. There are two reasons for this:Firstly, the mother always gives the male child the X chromosome and the father gives the Y chromosome.Secondly, in the case of a girl, she becomes a carrier but doesn’t get the disease. This is because the work of the defective X chromosome of the mother is carried out by the X chromosome from the father.
Girls always inherit the other X chromosome from their fathers and can only get the disease if both parents have sex-linked diseases.Women rarely get these diseases and end up being carriers who pass on the disease to their sons. Males have only one single X chromosome hence their susceptibility to the disease, since the X in the men doesn’t have a corresponding good gene in Y to cancel out the defectiveness.
Studies show that women with defective X chromosomes are very likely to pass it on to all their male children hence the IVF procedure.IVF involves a procedure of retrieving the eggs and the sperm, then fertilizing them in the laboratory. The resulting embryos are subjected to the Pre-Implantation Genetic Screening for sex selection to identify and transfer in to the woman’s womb only those that will result in the birth of a healthy baby.
DID YOU KNOW?
It is advisable for couples who want to give birth to girls that :the man and woman need to capitulate a few days to ovulation and then stop 24 hours before the onset of ovulation.
Y sperms move fast and die faster the X sperm that results in a girl. So if you have intercourse before ovulation, the Y or boy sperm would have long died by the time the egg is ready for fertilization. This means the X or girl sperms ,which can survive up to 3 days will be the only ones surviving to fertilize the egg.
For those who want a boy, the sex should take place at the onset of the ovulation and there after up to 24 hours after the ovulation-If relations occurs during ovulation, the likelihood of the child being a boy are high since the Y sperms move faster and reach the egg ahead of the X sperms.