What is jacob syndrome

XYY syndrome is a genetic condition that occurs when a male has an extra copy of the Y chromosome in each of their cells (XYY). Sometimes, this mutation is only present in some cells. Males with XYY syndrome have 47 chromosomes because of the extra Y chromosome. Most cases of 47,XYY syndrome are not inherited. The chromosomal change usually occurs as a random event during the formation of sperm cells. An error in cell division called nondisjunction can result in sperm cells with an extra copy of the Y chromosome.

Boys with XYY syndrome may have some or all of these physical symptoms to some degree:

• taller than average height.
• low muscle tone, or muscle weakness (called hypotonia)
• very curved pinky finger (called clinodactyly)
• widely spaced eyes (called hypertelorism)
• cystic acne during adolescence.