3 What is Jacob’s Syndrome? A rare chromosomal disorder that affects males. It is caused by the presence of an extra Y chromosome. Males normally have one X and one Y chromosome. However, individuals with Jacob's syndrome have one X and two Y chromosome.Males with Jacob's syndrome, also called XYY males.
5 Explanation.XYY syndrome is an aneuploidy of the sex chromosomes in which a human male receives an extra Y chromosomes, giving a total of 47 chromosomes instead of the more usual 46. This produces a 47, XYY karyotype.
6 Chemical Signs Of Jacob’s Syndrome High level of testosterone2. Have 47 chromosomes, XYY karyotype3. Delayed emotional maturity
7 Physical Symptoms Of Jacob’s Syndrome Large hand and feetSkeletal malformationSlightly taller than averageHaving more severe acne than normalLearning problems at schoolSpeech problemNormal sexual libido and potencySwollen jointsJoints stiffnessArthritisCamptodactylyImpaired joint mobilityInflammed pericardiumChest pain
8 What causes this disease? It is not inheritedOccurs as a random event during the formation of sperm cells.Error in chromosome separation during anaphase II (of meiosis II) called nondisjunction can result in sperm cells with an extra copy of the Y chromosome. If one of these atypical sperm cells contributes to the genetic makeup of a child, the child will have an extra Y chromosome in each of the body's cells.
9 continue…In some cases, the addition of an extra Y chromosome results from nondisjunction during cell division during a post-zygotic mitosis in early embryonic development. This can produce 46, XY/47, XYY mosaics.
10 How common is the disease?. About 1 in 1,000 boys are born with a 47, XYY karyotype. The incidence of 47, XYY is not affected by advanced paternal or maternal age.In Malaysia, when the population of the male is about 12,751.9 million, the number of those who are affected to this disease is 11,761. This is about 0.09%.