Genetic Essays - Cytogenetics, Aneuploidy, Genetic Disorder

Genetic Disorders Alterations in human chromosomes or the deletion of an important gene product are often due to a mutation, which can spring an abundant strand of genetic mutations and improper coding. Mutations can spring from deletion, duplication or inversion of a chromosome. This improper deletion is the factor that leads to complications and ultimately genetic disorders. Turner Syndrome and Cat-cry Syndrome are both alterations of chromosome structure due to deletion. In Turner Syndrome, there is a missing X chromosome and in the Cat-cry Syndrome chromosome-18 has been lost or deleted. Other genetic disorders that give rise to discussion are point mutations which include Sickle cell anemia, Maternal PKU and the genetic disorder of The D1 Trisomy syndrome. Turner Syndrome was described first by Turner in 1938 (Jack H. Hung 1989 p.45) and it was established that this disorder was due to the deletion of an X chromosome in 1959 by Ford, Jones, Polani, de Ameida and Briggs. The most predominant traits of those who have this disorder consist of being short, having neck webbing with a low hairline and having a widely spaced chest. Turner Syndrome disease is not a fatal disease as long as there is management of possible heart problems and ovarian dysfunction. Early support and counseling are the key in dealing with psychological problems that may arise such as infertility and potential hearing loss. Cat-cry Syndrome is another deletion disorder in which inhibitor survives quite well. Lejeune recognized this disorder in 1964 and he gave it the official name of La Maladie du Cri-du-Chat. The physical characteristics are evident in this disorder. There is a round moon-face, a low birth weight and a transverse palmar crease. When infants are born, it is their cry that stands out the most. It embodies a plaintive high-pitched wail, weak, and with a hint of stridor that sounds like that of a cat (Valtine 1969 p.113). This cry is the result of small vocal cords and a curved epiglottis. As these infants grow older their voice will eventually deepen and become more normal. The chromosome deletion is part of the short arm of a B group chromosome. It seems that the deletion comes about as a chance mishap, a break and then a loss at anaphase (Valtine 1969 p.114). Sickle cell disease is another disorder but is not caused by the deletion of a chromosome. Instead there is an abnormal type of hemoglobin S that is inherited as an autosomal inherited trait. This disease produces chronic anemia, which may become life threatening when hemolytic crises (the breakdown of redblood cells) or aplastic crises (bone marrow fails to produce blood cells) occur http://www.wcu.edu/library/online/index.htm). The incidence of this disorder is 1/400 African Americans and 8/100,000 people. The manifestations of this disease are a result of the fragility and inflexibility of the sickle red bloodcells. When exposed to a lack of water, infection, and low oxygen supply, these delicate red blood cells take the shape of a crescent. This then causes blood cell devastation and thickening of the blood. Sickle cell anemia has the potential to be life threatening and can affect other body systems and parts of the body. Those included are the nervous system, bones, the kidneys and the liver. Maternal PKU is a genetic disorder that stems from point mutation. 1/15,000 people fall victim to the disorder. Phenylketonuria (PKU) has been shown as a cause of retardation in infant fetuses. Children in the fetus begin with a normal amount of phenylalanine hydroxylase but are affected by the mother's elevated phenylalanine level due to the imbalance of prenatal amino acid (Kenneth Lyons Jones, M.D. 1988). Mental deficiency is clearly evident in disorder and usually consists of I.Q.s of 50. There are frequent mild manifestations of dysfunction and there are mild characteristics of a round face, thin upper lip, a small upturned nose and a deformed maxilla. Occasional abnormalities that are frequently associated with this disorder are sacral spine anomalies, cleft lip and irritability. The D1 Trisomy Syndrome is a very rare hideous disease that occurs during the time of infancy. Only just over a dozen cases on record. This diagnosis can often be made at birth due to the consistent abnormalities. "The baby is frail, puny, and microcephalic. There may be deformities of the scalp or skull and there is invariably cleft lip or palate (Kenneth Lyons Jones, M.D.). The fingers and toes are often disfigured on these victems. As far as the other body parts go, there is a congenital heart deformity and there is often abnormal lobulation of the lungs. Interestingly