Disorders genetic

Disorders Involving an Extra Autosome Down s syndrome (Trisomy 21) 

Most common of the chromosomal disorders Most common cause of inherited mental retardation 

Defined as a translocation involving two acrocentric chromosomes with the break points occurring close to the centromeres. This results in an extremely large chromosome and a tiny one, which Is typically lost. 

Mosaicism is defined as the presence of two or more populations of cells within an individual. 

Mental retardation Cleft lip and/or palate ii. Cardiac defects 

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L Xylulose (a 2 ketopentose excreted in excessive amounts in the urine of persons afflicted with the mild genetic disorder pentosuria)... 

Turner s Syndrome. Turner s syndrome is a genetic disorder of females characterized by short stature, nonfunctioning ovaries, and failure to develop secondary sexual characteristics. Several clinical trials in the United States, Europe, and Japan have demonstrated that hGH can accelerate... 

ADA SCID (adenosine deaminase-defective severe combined immunodeficiency) is a fatal genetic disorder caused by defects in the gene that encodes adenosine deaminase (ADA). 

Gene therapy uses cloned DNA in adeno or retroviral vectors to transduce host cells for longterm therapy of certain genetic disorders with defined... 

In central diabetes insipidus a hypophysial malfunction, caused by different diseases as well as head injuries, neurosurgery, or genetic disorders, leads to AVP hyposecretion. This type of diabetes insipidus can successfully be treated by the exogenous administration of AVP or AVP analogues (e.g. desmopressin). 

Genetic disorders of HDL metabolism have also resulted in greater understanding of the molecular regulation of HDL metabolism. Nonsense or missense mutations in apoA-I can result in substantially reduced HDL-C levels due to rapid catabolism of structurally abnormal or truncated apoA-I proteins. Tangier disease is a rare autosomal codominant disorder characterized by markedly low HDL-C and apoA-I levels and caused... 

In nephrogenic diabetes insipidus the kidney s ability to respond to AVP is impaired by different causes, such as drugs (e.g. lithium), chronic disorders (e.g. sickle cell disease, kidney failure) or inherited genetic disorders (X-linked or autosomal NDI). This type of diabetes insipidus can not be treated by exogenous administration of AVP or AVP analogues. Instead, diuretics (hydrochlorothiazide combined or not with amiloride) and NSAI (indomethacin) are administrated to ameliorate polyuria. 

McKusick VA Mendelian Inheritance in Man. Catalog of Human Genes and Genetic Disorders, 12th ed. Johns Hopkins Univ Press, 1998. [Abbreviated MIM]... 

Nutritional Genetic Disorders Can Impair Collagen Maturation... 

Homocarnosine (Figure 31-2), present in human brain at higher levels than carnosine, is synthesized in brain tissue by carnosine synthetase. Serum carnosinase does not hydrolyze homocarnosine. Homocarnosinosis, a rare genetic disorder, is associated with progressive spastic paraplegia and mental retardation. 

While purine deficiency states are rare in human subjects, there are numerous genetic disorders of purine catabolism. Hyperuricemias may be differentiated based on whether patients excrete normal or excessive quantities of total urates. Some hyperuricemias reflect specific en2yme defects. Others are secondary to diseases such as cancer or psoriasis that enhance tissue turnover. 

Martinez] et al Human genetic disorders, a phylogenetic perspective. J Mol Biol 2001 308 587. 

Cystic fibrosis (CF) is a recessive genetic disorder prevalent among whites in North America and certain parts of northern Europe. It is characterized by chronic bacterial infections of the airways and sinuses, fat maldigestion due to pancreatic exocrine insufficiency, infertility in males due to abnormal development of the vas deferens, and elevated levels of chloride in sweat (> 60 mmol/L). 

MANY METABOLIC GENETIC DISORDERS INVOLVE BONE... 

A number of the more important examples of metabolic and genetic disorders that affect bone are listed in Table 48-10. 

Another condition involving ceruloplasmin is aceru-loplasminemia. in this genetic disorder, levels of ceruloplasmin are very low and consequently its ferroxidase activity is markedly deficient. This leads to failure of release of iron from cells, and iron accumulates in certain brain cells, hepatocytes, and pancreatic islet cells. Affected individuals show severe neurologic signs and have diabetes mellitus. Use of a chelating agent or administration of plasma or ceruloplasmin concentrate may be beneficial. 

Genetic disorders of coagulation factors occur, and the two most common involve factors VIII (hemophilia A) and IX (hemophilia B). 

Hereditary elliptocytosis is a genetic disorder that is similar to hereditary spherocytosis except that affected red blood cells assume an elliptic, disk-hke shape, recognizable by microscopy. It is also due to abnormalities in spectrin some cases reflect abnormahties of band 4.1 or of glycophorin C. 

An extensive catalog of human genetic disorders, updated daily. 

The major Impetus to the development of methods for the prenatal detection of genetic disorders derives. In historical terms, from the roughly simultaneous development of three major techniques (11-14). One was the technique, and the willingness to use It, for obtaining samples of amnlotlc fluid early In gestation. The second was the development of techniques for the culture of human cells in vitro, and the third was the development of better techniques for cytogenetic analysis. As will be described below, with the availability of these three techniques It became possible first to work out methods for the examination of fetal chromosomes, and then, by extension, to devise ways of determining other characteristics of the fetus. 

Frequency of genetic disorders In the English newborn population... 

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