An estimated 50% of Klinefelter’s cases are a result of maternal meiotic errors. Variants of Klinefelter syndrome occur more infrequently; approximately 1 in 50,000 or fewer newborns has a variant of Klinefelter syndrome.Most men are diagnosed as adults in the context of male infertility. , "What are common symptoms of Klinefelter syndrome (KS)? As shown in Figure 1.1 non-disjunction within Meiosis I will result in a two trisomic gametes and two monosomic gametes (as shown on the right side of Figure 1.1). About 10% of XXY males have gynecomastia noticeable enough that they may choose to have cosmetic surgery. , During puberty, the physical traits of the syndrome become more evident; because these boys do not produce as much testosterone as other boys, they have a less muscular body, less facial and body hair, and broader hips. In 1959, these men with Klinefelter syndrome were discovered to have an extra X chromosome (genotype XXY) instead of the usual male sex complement (genotype XY). The diagram below further shows the process of nondisjunction replication in meiosis 1 and 2. The extra X chromosome undergoes inactivation to compensate for the excess genetic dosage. Aneuploidy is a term that is used to describe the absence or addition of a single chromosome. (a) Individual; (b) Karyotype. Often there is an azoospermia present, rarely an oligospermia. , The use of behavioral therapy can mitigate any language disorders, difficulties at school, and socialization. ", "Increased mortality in Klinefelter syndrome", "Mortality in patients with Klinefelter syndrome in Britain: a cohort study". Abnormal Meiosis and Fertilization Non-disjunction Disorders: • Occur when the homologous chromosomes fail to _____ to opposite poles of the cell during meiosis. Klinefelter syndrome is associated with decreased levels of testosterone and is the most common cause of … Okay, here we go: For an example, let's keep it simple and just look at the two sex chromosomes. (a) Individual; (b) Karyotype.  People with the condition have a nearly normal life expectancy. A mosaic such as (46, XY/47, XXY) may result from nondisjunction occurring during mitosis, especially at a very early stage of development. Homologous chromosomes Chiasma Recombinant chromatids Sinauer Associates, Inc 820 0.18 Diploid Unfertilized egg Haploid Haploid Fertilized egg Diploid . Klinefelter: Klinefelters is a genetic disease caused by what is called "nondisjunction". An individual with an error in chromosome number is described as aneuploid, a term that includes monosomy (loss of one chromosome) or trisomy(gain of an extraneous chromosome). The Klinefelter-Reifenstein-Albright syndrome.  Enlarged breasts may be removed by surgery. Maternal meiosis II nondisjunction in a case of 47,XXY testicular feminization. , XXY males are more likely than other men to have certain health problems, such as autoimmune disorders, breast cancer, venous thromboembolic disease, and osteoporosis. Klinefelter syndrome is a chromosomal aneuploidy characterized by the presence of 1 or more extra X chromosomes in a male karyotype, most commonly leading to karyotype 47,XXY. During meiosis 2, one of the chromosome pairs separates successfully. , The primary features are infertility and small poorly functioning testicles. 1. Change ). An individual with the karyotype 48, XYYY would have how many Barr bodies? Which of the following events could not give rise to a Klinefelter male? This preview shows page 1 out of 1 page. Key Words: Klinefelter syndrome, spermatogenesis, meiosis, sperm aneuploidy, TESE Sometimes, symptoms are more evident and may include weaker muscles, greater height, poor coordination, less body hair, breast growth, and less interest in sex. An individual with the appropriate number of chromosomes for their species is called euploid; in humans, euploidy corresponds to 22 … Question I came across a problem online that was comparing the two in the context of Klinefelter/Turner syndrome, and my brain got absolutely warped trying to figure out the differences between nondisjunction meiosis 1 vs meiosis 2. I dont understand why nondisjunction only occured with the mom and how im supposed to distinguish between nondisjunction in meiosis 1 and 2. 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