Jacob’s Syndrome is a rare chromosomal genetic syndrome where the male has an extra Y male chromosome and ends up having 47 chromosomes with XYY instead of normal 46,XY (male) or 46, XX (female.) It is very rare and happens in only about 1 out of 1,000 men. The exact reason for this is unknown. In a very rare cases it was passed from father to son, but in most cases it is not hereditary. It was first discovered by Patricia Jacobs in 1965. She proposed the suggestion that the extra Y chromosome might lead to increased aggression in these men and might land them in trouble with the law.
Usually this chromosomal change doesn’t cause any unusual physical features or medical problems. 47,XYY boys and men are usually taller than average and about seven centimeters taller than their parents and siblings. Bad acne was noticed in very few early case reports, but dermatologists specializing in acne now doubt that there's any relation between the two. Boys with XYY are usually normally developed at birth with normal birth weight and length without any abnormal physical features.
Boys with XYY are often more physically active than their brothers, and if this activity is accepted, sports and other physical activities together with the parents and together with other children isn’t bad in any way. These boys are usually slow at developing emotional maturity, and this sometimes leads to to learning problems in school.
It's really important that these boys at an early age go to a good kindergarten, and that the staff of the kindergarten and the parents have a good relationship. If learning to speek is a little slow it would be good to get a speech teacher for a while. In general XYY boys usually develop normally during childhood.
XYY boys are usually within the normal range at school, but with a tend to have a few small learning problems and school problems. That can be helped a lot by hiring special teachers and tutors. Learning problems are most...