Child birth 

Genetic diseases may be caused by several factors. An inherited condition comes from parents' genes. A chromosomal disorder can occur even if parents do not have risk factors. Multifactor diseases arise from several sources, the cause being generally unknown.

Chromosomal disorders occur when a gene shows damage, is plus or missing; this situation occurs when sperm and egg combine to form a zygote. Two well known examples are Down syndrome and Trisomy-18.

Multifactorial diseases are generally caused by more than one factor, often causes remaining unknown. Palace split, clubfoot, or neural defects in the abdominal wall may be reported. Advances were made in neural disease and now all childbearing age women are encouraged to consume a minimum amount of folic acid, which helps prevent neural tube defects.

There are three main categories of genetic disorders - dominant, recessive and X chromosome disorders.

• Dominant disorders can arise if one parent has a disease related to a dominant gene. There is a 50% chance that any children of that couple inherit the disease. Among the diseases related to a dominant gene there are included Huntington disease (Huntington's chorea) and polydactyly (more fingers at hands or feet).
• Recessive diseases can arise if both parents are carriers or responsible for gene disease. In this situation, the child has a 25% chance of inheriting the disease, 50% likely to be carrier and 25% chance of not at all inheriting the gene. Recessive disorders examples include sickle cell anemia, Tay-Sachs disease and cystic fibrosis.
• X chromosome disorders occur when a woman is a carrier of a X chromosome disease and gives birth to a male child. The child has a 50% chance to inherit the condition. If the baby is a girl, that is 50% likely to be and carry it. Hemophilia, fragile X chromosome syndrome and Duchenne muscular dystrophy are examples of diseases of the X chromosome.