Program Success Fall 2017 | Page 13



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Charles E . Simmons , MD Dominique D . Barrs Gene Disorders Daytona Beach , Florida Fall 2017


► There are many disorders that a person may acquire due to defaults in genes . The consequences of these genes may appear mild or moderate , or may have severe or no apparent effect . Right after birth , or early in life , the symptoms may become obvious . Some are not discovered , however , until adult life . No matter when they arise , these defective genes have been inherited by the child from their parent . Gene disorders result in a defect in one or more of the genes that are carried on the individual chromosomes .


A person who is color blind finds it more difficult to disli guish between the colors red and green , or the less common blue and yellow pair because of a defect in the cones in the retina of the eye . The disorder is inherited by a faulty gene carried on the X chromosome . Usually males are the victims of being color blind because they have only one X chromosome , and the defect carried is more likely to be expressed . A female has two X chromosomes , and a fault on one chrome some will be overridden by the other chromosome . Therefore , the female becomes the carrier and never will experience the color blindness , only males . This type of inheritance is called the X-linked recessive , and there is a 25 % chance that a male will be affected .


Albinism is a disorder characterized by a lack of the brown pigment called Melanin . An affected individual may have no pigment in the hair , skin , and eyes . The hair is usually white ; the skin is pale , and eyes range from pink to very pale blue . The eyes are very sensitive to bright light and visual impairment is common . Albinism is caused by a recessive gene , which means that a child has to inherit a defective gene from each parent . The gene causes a fault in the enzyme that is responsible for melanin production .
Huntington ' s disease causes involuntary movements , personality changes , and progressive dementia . This is one disorder that symptoms usually don ' t develop until over the age of 30 because deterioration occurs over the span of 15- 20 years . Huntington ' s disease is caused by an abnormal dominant gene , therefore each child has a 1 in 2 chance ( 50 %) of inheriting the faulty gene .


Hemoglobin , the pigment that gives red blood cells their color , carries oxygen in the blood . When hemoglobin is deficient or abnormal , the term anemia is used . Therefore , there is a lack of oxygen being supplied to body tissues . There are many forms of anemia , but one found in people of color is the sickle-cell disease , in which the red blood cells are distorted into a curved sickle shape . A comparison between the defected sequence and the normal sequence determines the nature of the amino acid error . This was the way that the molecular basis of Sickle Cell Anemia was determined , now known to result from a Valine to Glutamine Acid substitution in position 6 of the beta-globin .
It is vitally important for a mother to receive the proper prenatal and postnatal care to fully understand the risks in possible future generations . Genes are inherited and ii is always helpful to be aware of what genes both the mother and father can give to the offspring . Therefore , the precautions and proper care can be administered .