الفهرس 
الملخص العربي
Blood DiseasesOnly 14 pages are availabe for public view
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Abstract
In this review we discuss genetic diseases which are diseases caused by abnormalities in genes or chromosome and methods of carrier detection in these diseases.
Carrier is an individual who has recessive, disease causing gene mutation at a particular locus on one chromosome of a pair and a normal allele at that locus on the other chromosome may also refer to an individual with a balanced chromosome rearrangement.
Carrier Testing:
Are testing used to identify usually asymptomatic individuals who have agene mutation for an autosomal recessive or x- linked disorder.
- Preimplantation genetic diagnosis:
An established procedure of embryo genetic analysis. It allows couples carrying genetic diseases to have an unaffected child. Without facing prenatal diagnosis and termination of pregnancy.
It consists in realizing genetic analysis on embryonic cells and transferring the embryos identified unaffected into the uterus.
There are many indications for preimplantation genetic diagnosis as B- thalassemia, cystic fibrosis and sickle cell anemia.
There are multiple methods to do preimplantation genetic diagnosis as biopsy, genetic analysis and comparative genomic hybridization.
- Prenatal diagnosis:
Testing performed during pregnancy to determine if afetus is affected with a particular disorder.
There are many indications for prental diagnosis as chromosomal abnormality, in a previous offspring; previous offspring with multiple malformation and mucopolysaccharidosis.
The availability of prenatal diagnosis give couples options they might not have other wise, including preparation for the birth of achild with an abnormality, termination of an affected pregnancy or use of fetal treatment such as fetal surgery for spin bifida.
There are many techniques for prenatal diagnosis as:
Amniocentesis, chorionic villus sampling, ultrasonography and fetal echocardiography .
Genetic counseling is a communication process which deals with the human problems associated with the occurrence or risk of occurrence of a genetic disorder in a family. This process involves an attempt by one or more appropriately trained persons to help the individual or family to:
1- Comprehend the medical facts including diagnosis, probable course of the disorder, and the available management.
2- Appreciate the way heredity contributes to the disorder and the risk of recurrence in specified relatives.
3- Understand the alternatives for dealing with the risk of recurrence.
4- Choose course of action which seems appropriate for them in view of their risk, their family goals and their ethical and religious standards and act in accordance with the decision and, to make the best possible adjustment to the disorder in an affected family member and or to the risk of recurrence of that disorder.
There are many indications for genetic counseling as:
1- Individuals/ couples who have family history of an inherited condition, mental retardation or a birth defect.
2- Women / couples who have had two or more miscarriages or unexplained infant deaths.
3- Couples who are close relatives.
4- Advanced maternal age.
Premarital Screening:
A premarital test is defined as a test in which couples that are going to get married are tested for genetic, infectious and blood transmitted diseases to prevent any risk of transmitting any disease to their children.
These tests include:
• Complete blood count (CBC) .
• Blood group (ABO & Rh typing) .
• Abnormal Haemoglobin studies (Hb Variants) .
• G6PD- quantitative.
• Sexually transmitted diseases screening tests as hepatitis BSAg screening.
Lastly:
Carrier detection in genetic diseases is important for diagnosis, treatment and prevention of genetic disease.