Genetic disorders autosomal recessive

Sickle cells were first identified by physician James Herrick in a 20-year-old medical student from Grenada in 1910.1 O Sickle cell syndrome refers to a collection of autosomal recessive genetic disorders that are characterized by the presence of at least one sickle hemoglobin gene (HbS).2,3... 

Sickle-cell syndrome A group of autosomal recessive genetic disorders characterized by the presence of at least one sickle-hemoglobin gene. 

It is important to note that the chance of passing on a genetic condition applies equally to each pregnancy. For example, if a couple has a child with an autosomal recessive disorder, the chance of having another child with the disorder is still 25 percent (or 1 in 4). Having one child with a disorder does not "protect" future children from inheriting the condition. Conversely, having a child without the condition does not mean that future children will definitely be affected. 

Reduced penetrance and variable expressivity are factors that influence the effects of particular genetic changes. These factors usually affect disorders that have an autosomal dominant pattern of inheritance, although they are occasionally seen in disorders with an autosomal recessive inheritance pattern. 

A couple undergoes genetic counseling for consultation on the possibility that they may have a child with Friedrich s ataxia, an autosomal recessive neuromuscular disorder. The disorder has been diagnosed in the wife s sister, and they are concerned that she is a carrier. The incidence of the disorder in the population is 1 in 25,000 live births. 

Bayesian probabilities are absolutely reliant upon an accurate family history of the disease in question. Family history affects the prior or a priori likelihood that a propositus is a carrier for a genetic disease. Because many hereditary disorders are autosomal recessives and manifest rarely in a sibship, any record of a known hereditary disorder can be important in providing an accurate risk reduction. This can be particularly important in cystic fibrosis, where one of the mutations is often known in affected individuals while the other is often private and uncharacterized. Fven an affected first cousin can boost the a priori probability in a Caucasian non-Jew from 1/241 to 1/8. 

Genetic mutations are a major cause of DPD impairment (24,58). Polymorphism of the DPYD gene has been well characterized as an autosomal recessive disease, with 0.5% and 3%-5% of the Caucasian population being subsequently affected by total and partial deficiencies, respectively (7,59,60). Thymine uraciluria is a condition caused by inherited total DPD deficiency that can be either associated with neurological disorders or be asymptomatic (61,62,63). 

Waterham HR, Koster J, et al. (2001) Mutations in the 3/3-hydroxystcroid 24-reductase gene cause desmosterolosis, an autosomal recessive disorder of cholesterol biosynthesis. Am J Hum Genet 69 685-694... 

Cause/Incidence Hereditary autosomal recessive genetic disorder first described by Wilson in 1912, which gives rise to altered copper transport resulting in excess metal storage. This condition is more commonly observed in males, with an incidence of around 1 in 30 000, and it is believed 1 in 100 individuals are imaffected carriers. 

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