Question: What is (are) 47, XYY syndrome ?
Answer: 47, XYY syndrome is a condition in males characterized by features that occur due to having an extra copy of the Y chromosome in each cell. Signs and symptoms can vary and range from barely noticeable to more severe; many men with the extra Y chromosome are completely unaware of its presence. Appearance and intelligence are usually normal, but learning disabilities may be present. Other signs and symptoms may include autism spectrum disorder (usually on the milder end); speech or motor delay; low muscle tone; asthma; tall stature; impaired social skills; ADHD; and/or anxiety or mood disorders. While sexual development and infertility is usually normal, some adolescents and adults have testicular failure. 47, XYY syndrome usually is not inherited, occurring due to a random event in the formation of a sperm cell prior to conception. Management depends on the symptoms in each person and may include intervention or therapies for developmental delays, behavior or mood disorders; and/or special education.
Source: GARD

Question: What causes 47, XYY syndrome ?
Answer: What causes 47, XYY syndrome? 47,XYY syndrome is caused by the presence of an extra copy of the Y chromosome in each of a male's cells. This is typically due to a random event during the formation of a sperm cell in the father, usually before conception (fertilization of the egg). In this case, the father's two Y chromosomes do not separate when sperm cells are being made. If two Y chromosomes are present in a sperm that fertilizes an egg (with an X chromosome), the resulting embryo will be a male with an extra Y chromosome. It is also possible that a similar random event could occur very early in an embryo's development. It is not fully understood why an extra copy of the Y chromosome leads to an increased risk for the features associated with 47, XYY syndrome in some males. Importantly, there is nothing either parent can do (or not do) to cause or prevent 47, XYY syndrome.
Source: GARD

Question: Is 47, XYY syndrome inherited ?
Answer: Is 47, XYY syndrome inherited? 47, XYY syndrome is usually not inherited. It is typically due to a random event during the formation of a sperm cell. Recurrence of 47, XYY syndrome in a family is rare. The recurrence risk for siblings and other family members is not thought to be increased. Additionally, men with 47, XYY are not reported to have an increased risk for a child with a chromosome variation. People with personal questions about recurrence risks are encouraged to speak with a genetic counselor or other genetic professional.
Source: GARD