What causes Jacobs syndrome?Jacobs syndrome occurs when a male inherits two Y chromosomes from his father instead of one. He is an XYY male. Most males are XY.The exact cause of the XYY aberration is unknown.
WHAT ARE SYMTOMSOF JACOBSYNDROME?learning problems at schooldelayed emotional maturity
What are the PhysicalCharacteristics of JacobsSyndrome?Males with Jacob’s syndrome are tall, thin, have acne, speech problems, and reading problems.
In 1956, Drs. Joe Hin Tjio and Albert Lavan confirmed that there were 23 pairs of chromosomes in humans. Up until that time, it had been thought that there were 48 chromosomes. However, using a more advanced experimental technique, Tjio and Lavan were able to confirm that there are typically, in fact, only 46 chromosomes. Because men commonly have 22 pairs of autosomes, plus one X and one Y sex- determining chromosome,
men are referred to as 46,XY; andbecause women commonly have thesame 22 pairs of automsomes plus twoX chromosomes, they are referred to bygeneticists as 46,XX. The discovery byTjio and Lavan is generally consideredto be the beginning of modern“cytogenetics,” which is the study ofchromosomes and the diseases causedby either numerical and/or structuralabnormalities in them.
Three years following this discovery, in 1959, a young English researcher named Patricia Jacobs and her associate described the first chromosmal abnormality in man, the extra X chromosome that is found in an estimated 80% of the men with klinefelter syndrome; and later that year, Dr. Jacobs identified the extra X in trisomy X (47,XXX). Approximately two years later, in 1961, Dr. Avery Sandberg and his associates published a paper in the medical journal Lancet reporting the first man to be discovered with an extra Y chromosome in his cells.