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Genetic disorders

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)

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