Understanding Klinefelter Syndrome: Genetics and Symptoms

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In 1942 Doctor Harry Klinefelter wrote a paper about some men who he found had strange symptoms. These symptoms included very little facial/body hair, small testes, and an inability to produce sperm. Seventeen years later in 1959 the extra X chromosome that is characteristic of the condition was discovered. Klinefelter Syndrome is a condition that affects male chromosomes. Humans in general have about 46 chromosomes in total. Out of these 46, only two will determine if a person will be male or female. The sex chromosomes in women typically present as XX, while the sex chromosomes in males present as XY. With Klinefelter syndrome, also known as (47, XXY) and XXY Syndrome only males are able to affected with this chromosomal condition where they end up with an extra X chromosome on almost all of their cells. GENETICS OF THE DISEASE Klinefelter Syndrome, as previously stated, is a chromosomal condition process begins during meiosis. Before meiosis has finished chromosomes pair up with their corresponding half and they exchange pieces of genetic material, however something may go wrong during the process and sister chromatids might not separate completely. During normal embryonic development one of the two X chromosomes from the mother are made inactive. In some 15% …show more content…

It is composed of eight exons, segments of DNA that contain the information for coding both proteins and peptides. The first exon of the AR gene has a polymorphic sequence of CAG repeats - CAG being the combination of nucleotide bases that occur in this exon- that varies in number from ten to thirty-five repeats in a normal X chromosome. In one study of 77 recently diagnosed men that the average CAG repeat was 23 times on the first exon. In the same study a longer CAG repeat number was associated with patient height – the longer the repeat the taller the patient- lower bone density and gynecomastia. VARIATIONS ON A

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