Various Genetic Disorders Various 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 enough, these bizarre deformities are present due to one of the chromosomes in Group D, but it is hard to say which one because the D chromosomes cannot be distinguished. The disorder of the D1 Trisomy syndrome is fatal and the babies are expected to live only a few days or weeks, some have lived to 2 or 3 years. If the baby does live past infancy, severe mental defects take their toll.
This disorder stood out to me due to the nature of its mysterious formation. It is not known whether pair 13,14, or 15 arise conflict in the chromosomes. Through conducting research on genetic disorders I have come into contact with books that hold hundreds of genetic disorders and most of these pictures are those of children. I picked this topic due to my interest on the topic, but was completely unaware of the graphic nature of some of these disorders. Theodore Roosevelt quotes Far better it is to dare mighty things, to win glorious triumphs, even though checkered by failure, than to take rank with those poor spirits who neither enjoy much nor suffer much, because they live in the great twilight that knows neither victory nor the feeling of defeat. The genetic disorders of today can not be totally wiped off the face of the planet, but can be somewhat predicted with the help of family trees and common knowledge of ancestors.
Bibliography Kenneth Lyons Jones, M.D. 1988. Smiths Recognizable Patterns of Human Malformation pp.520-521 W. B. Saunders Company.
G.H. Valentine, M B. 1969. The Chromosome Disorders pp. 113-115 pp.
103-106 Printed in Great Britain by The Whitefriars Press Ltd. London and Tonbridge. Jack H. Jung, M.D. 1989.
Genetic syndromes in Communication Disorders pp. 45 PRO-ED Printed in the United States of America. Neil A Campbell, Lawrence G. Mitchell, Jane B. Reece. 1997.
Biology concepts and connections. In The Human Genome pp. 238-239 The Benjamin/cummings Publishing Company. Arthur Metcalf. Sickle Cell Diesase.
Accessed 4/20/99 through Dogpile. http://www.wcu.edu/library/online/index.htm).