Description
47,XYY syndrome is characterized by an extra copy of the Y chromosome in each of an individual's cells. Although many people with this condition are taller than average, the chromosomal change sometimes causes no unusual physical features. Most individuals with 47,XYY syndrome have normal production of the male sex hormone testosterone and normal male sexual development, and they are usually able to father children.
47,XYY syndrome is associated with an increased risk of learning disabilities and delayed development of speech and language skills. Affected children can have delayed development of motor skills (such as sitting and walking) or weak muscle tone (hypotonia). Other signs and symptoms of this condition include hand tremors or other involuntary movements (motor tics), seizures, and asthma. Individuals with 47,XYY syndrome have an increased risk of behavioral, social, and emotional difficulties compared with their unaffected peers. These problems include attention-deficit/hyperactivity disorder (ADHD); depression; anxiety; and autism spectrum disorder, which is a group of developmental conditions that affect communication and social interaction.
Physical features related to 47,XYY syndrome can include increased belly fat, a large head (macrocephaly
Frequency
This condition occurs in about 1 in 1,000 newborns. Five to 10 children with 47,XYY syndrome are born in the United States each day. Many affected individuals are never diagnosed or not diagnosed until later in life.
Causes
People normally have 46 chromosomes in each cell. Two of the 46 chromosomes, known as X and Y, are called sex chromosomes
47,XYY syndrome is caused by the presence of an extra copy of the Y chromosome
Some people with 47,XYY syndrome have an extra Y chromosome in only some of their cells. This phenomenon is called 46,XY/47,XYY mosaicism
Inheritance
47,XYY syndrome is not inherited. The chromosomal change 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
46,XY/47,XYY mosaicism is also not inherited. It occurs as a random event during cell division
Other Names for This Condition
- Jacob's syndrome
- XYY karyotype
- XYY syndrome
- YY syndrome
References
- Bardsley MZ, Kowal K, Levy C, Gosek A, Ayari N, Tartaglia N, Lahlou N, Winder B, Grimes S, Ross JL. 47,XYY syndrome: clinical phenotype and timing of ascertainment. J Pediatr. 2013 Oct;163(4):1085-94. doi: 10.1016/j.jpeds.2013.05.037. Epub 2013 Jun 27. Citation on PubMed or Free article on PubMed Central
- Geerts M, Steyaert J, Fryns JP. The XYY syndrome: a follow-up study on 38 boys. Genet Couns. 2003;14(3):267-79. Citation on PubMed
- Lalatta F, Folliero E, Cavallari U, Di Segni M, Gentilin B, Fogliani R, Quagliarini D, Vizziello P, Monti F, Gargantini L. Early manifestations in a cohort of children prenatally diagnosed with 47,XYY. Role of multidisciplinary counseling for parental guidance and prevention of aggressive behavior. Ital J Pediatr. 2012 Oct 3;38:52. doi: 10.1186/1824-7288-38-52. Citation on PubMed or Free article on PubMed Central
- Robinson DO, Jacobs PA. The origin of the extra Y chromosome in males with a 47,XYY karyotype. Hum Mol Genet. 1999 Nov;8(12):2205-9. doi: 10.1093/hmg/8.12.2205. Citation on PubMed
- Ross JL, Roeltgen DP, Kushner H, Zinn AR, Reiss A, Bardsley MZ, McCauley E, Tartaglia N. Behavioral and social phenotypes in boys with 47,XYY syndrome or 47,XXY Klinefelter syndrome. Pediatrics. 2012 Apr;129(4):769-78. doi: 10.1542/peds.2011-0719. Epub 2012 Mar 12. Citation on PubMed or Free article on PubMed Central
- Tartaglia NR, Wilson R, Miller JS, Rafalko J, Cordeiro L, Davis S, Hessl D, Ross J. Autism Spectrum Disorder in Males with Sex Chromosome Aneuploidy: XXY/Klinefelter Syndrome, XYY, and XXYY. J Dev Behav Pediatr. 2017 Apr;38(3):197-207. doi: 10.1097/DBP.0000000000000429. Citation on PubMed or Free article on PubMed Central