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Image: example of karyotyping showing a total of 46 chromosomes in the genome. Molecular cytogenetics combines two disciplines, molecular biology and cytogenetics, and involves the analysis of chromosome structure to help distinguish normal and cancer-causing cells. Human cytogenetics began in 1956 when it was discovered that normal human cells ...
Women at 40 years have a four-times-higher risk of a child with Klinefelter syndrome than women aged 24 years. [ 15 ] [ 35 ] [ 36 ] The extra chromosome is retained because of a nondisjunction event during paternal meiosis I , maternal meiosis I, or maternal meiosis II , also known as gametogenesis .
XX male syndrome, also known as de la Chapelle syndrome, is a rare intersex condition in which an individual with a 46,XX karyotype develops a male phenotype. [2] Synonyms for XX male syndrome include 46,XX testicular difference of sex development (or 46,XX DSD) [3] [4] [5] [6]
Three chromosomal abnormalities with ISCN nomenclature, with increasing complexity: (A) A tumour karyotype in a male with loss of the Y chromosome, (B) Prader–Willi Syndrome i.e. deletion in the 15q11-q12 region and (C) an arbitrary karyotype that involves a variety of autosomal and allosomal abnormalities. [3]
46,XX/46,XY chimeric or mosaic is associated with a wide spectrum of different physical presentations, with cases ranging from having a completely normal male or female phenotype [7] [8] [9] to some cases having ovotesticular syndrome. Due to this variation, genetic testing is the only way to reliably make a diagnosis.
The results are summarized and given to a board-certified cytogeneticist for review, and to write an interpretation taking into account the patient's previous history and other clinical findings. The results are then given out reported in an International System for Human Cytogenetic Nomenclature 2009 (ISCN2009)..
The first published report of a boy with a 48,XXYY karyotype was by Sylfest Muldal and Charles H. Ockey in Manchester, England in 1960. [9] It was described in a 15-year-old mentally disabled boy who showed signs of Klinefelter syndrome ; however, chromosome testing revealed 48,XXYY instead of the 47, XXY arrangement known to cause Klinefelter ...
Starting first from cytogenetics in the nineteens, the Atlas now combines different types of knowledge in a single web site: genes and their function, cell biology (ex: Apoptosis), [2] pathological data, diseases and their clinical implications, cytogenetics, but also medical genetics, with hereditary disorders associated with an increased risk ...