Clinical Presentation of Genetic Disorders in Patients Attending Genetic Outpatient Clinic of Assiut University Children Hospital

Genetic Epidemiology : is quickly expanding research field concerned with considerate the heritable aspect of disease risk, individual propensity to disease and eventually with contributing to a complete molecular understanding of pathogenesis. Genetics : is the scientific study of genes \&heredity of how certain qualities or traits are passed from parents to offspring as a result of changes in DNA sequence . A gene is a segment of DNA that contains instructions for building of one or more molecules Genetic disorders: is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosomal abnormality. (1)mutations: affect the human genes either inherited from one or both parents or due to certain environmental factors Four of the main types include:(1)Single \_gene inheritance diseases :Single gene inheritance diseases are diseases that occur because one defective gene is present. They are known as monogenetic disorders.(EX:Marfan Syndrome ) (2)Multifactorial genetic inheritance disorders : Genetic disorders may also be complex, , meaning they are likely associated with the effects of multiple genes in combination with lifestyles and environmental factors. Multifactorial disorders include heart disease and diabetes. (3)chromosomal abnormalities : result from a problem with cell division and arise because of duplications or absences of entire chromosomes or pieces of chromosomes. Examples of chromosome abnormality disorders include(Down sydrome ) (4)Mitochondrial genetic inheritance disorders : are caused by mutations in the DNA of mitochondria, small particles within cell. Mitochondrial DNA is always inherited from the female parent since egg cells (unlike sperm cells) keep their mitochondrial DNA during the process of fertilization. Environmental Factors: called (mutagens)which can lead to genetic mutations Such as Chemical exposure , Radiation exposure , Sm