AUTOSOMAL RECESSIVE DISORDERS Autosomal recessive disorders are those that are inherited by means of the autosomal genes. Being recessive, they are not necessarily clinically apparent when the gene is inherited because there will be another gene that will “cover” for the abnormal gene so that the individual won’t get the disorder until the person has two copies of the abnormal gene. This leads to the possibility of a carrier status, in which the person has the ability to pass on the gene but does not have the disease themselves. Two carriers will have a 25 percent chance of having a child with the disease. These are the common autosomal recessive diseases: •
Cystic fibrosis—this is an autosomal recessive disease that involves a defect in the CFTR gene on chromosome 7. Chloride ion transport fails to happen so there are excessively viscous mucous secretions. Children will have meconium ileus from thick meconium, respiratory bronchiectasis, pancreatic insufficiency, high sweat chloride concentration, and a high risk of Pseudomonas pneumonia infections.
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Fanconi anemia—this is an autosomal recessive pancytopenia, leading to both anemia and neutropenia. Children will have mental retardation, short stature, microcephaly, hypogenitalism, microphthalmia, and bony abnormalities.
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Hartnup’s disease—this is a defect in the gastrointestinal uptake of certain amino acids and niacin. It is autosomal dominant and leads to a syndrome typical of pellagra, with diarrhea, dermatitis, and dementia. They will have brain dysfunction with transient cerebellar ataxia.
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Kartagener’s syndrome—this is an autosomal recessive disorder that leads to a lack of motility of the cilia. It leads to recurrent sinus and lung infections and situs inversus due to impaired ciliary motion during embryogenesis. The thoracic organs will also be on the opposite side of the body with possible dextrocardia. Males will be sterile because of a lack of ciliary motion.
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Pyruvate dehydrogenase deficiency—this is an autosomal recessive disorder and a deficiency of the enzyme pyruvate dehydrogenase. This causes lactic acidosis from a buildup of lactate and pyruvate in the bloodstream. The treatment is to 10
