[7][12][13][14] In contrast to the other common sex chromosome aneuploidies—47,XXX and 47,XXY (Klinefelter syndrome)—the average of the IQ scores of 47,XYY boys identified by newborn screening programs was not reduced compared to the general population.

[18] Approximately half of 47,XYY boys identified by newborn screening programs had learning difficulties—a higher proportion than found among siblings and above-average-IQ control groups.

[19] Developmental delays and behavioral problems are also found, but these characteristics vary widely among affected boys and men, are not unique to 47,XYY and are managed no differently from in 46,XY males.

Patients with Jacobs syndrome have been shown to have a higher risk of developing certain diseases such as asthma, seizure problems, and tremors.

The syndrome is diagnosed in an increasing number of children prenatally by amniocentesis and chorionic villus sampling[24] in order to obtain a chromosome karyotype, where the abnormality can be observed.

[7][12] In April 1956, Hereditas published the discovery by cytogeneticists Joe Hin Tjio and Albert Levan at Lund University in Sweden that the normal number of chromosomes in diploid human cells was 46—not 48, as had been believed for the preceding thirty years.

[12] In January 1968 and March 1968, The Lancet and Science published the first U.S. reports of tall, institutionalized XYY males by Mary Telfer, a biochemist, and colleagues at the Elwyn Institute.

[46] In June 1969, the National Institute of Mental Health (NIMH) Center for Studies of Crime and Delinquency held a two-day XYY conference in Chevy Chase, Maryland.

[47] In December 1969, with a grant from the NIMH Center for Studies of Crime and Delinquency, cytogeneticist Digamber Borgaonkar at Johns Hopkins Hospital began a chromosome survey of (predominantly African-American) boys ages 8 to 18 in all Maryland institutions for delinquent, neglected, or mentally ill juveniles, which was suspended from February–May 1970 due to an American Civil Liberties Union (ACLU) lawsuit regarding the study's lack of informed consent.

[52][53] In December 1969, Lore Zech at the Karolinska Institute in Stockholm first reported intense fluorescence of the A T-rich distal half of the long arm of the Y chromosome in the nuclei of metaphase cells treated with quinacrine mustard.

[54] In April 1970, Peter Pearson and Martin Bobrow at the MRC Population Genetics Unit in Oxford and Canino Vosa at the University of Oxford reported fluorescent "male" sex chromatin bodies in the nuclei of interphase cells in buccal smears treated with quinacrine dihydrochloride, which could be used to screen for Y chromosome aneuploidies like 47,XYY.

[37] In November 1974, Science for the People went public with their objections to the Boston XYY study in a press conference and a New Scientist article alleging inadequate informed consent, a lack of benefit (since no specific treatment was available) but substantial risk (by stigmatization with a false stereotype) to the subjects, and that the unblinded experimental design could not produce meaningful results regarding the subjects' behavior.

[60] In August 1976, Science published a retrospective cohort study by Educational Testing Service psychologist Herman Witkin and colleagues that screened the tallest 16% of men (over 184 cm (6'0") in height) born in Copenhagen from 1944 to 1947 for XXY and XYY karyotypes, and found an increased rate of minor criminal convictions for property crimes among sixteen XXY and twelve XYY men may be related to the lower intelligence of those with criminal convictions, but found no evidence that XXY or XYY men were inclined to be aggressive or violent.

[12][63] In May 1997, Nature Genetics published the discovery by Ercole Rao and colleagues of the X/Y chromosome pseudoautosomal region (PAR1) SHOX gene, haploinsufficiency of which leads to short stature in Turner syndrome (45,X).

[9] In July 1999, Psychological Medicine published a case-control study by Royal Edinburgh Hospital psychiatrist Michael Götz and colleagues that found an increased rate of criminal convictions among seventeen XYY men identified in the Edinburgh newborn screening study compared to an above-average-IQ control group of sixty XY men, which multiple logistic regression analysis indicated was mediated mainly through lowered intelligence.

[65] In June 2002, the American Journal of Medical Genetics published results from a longitudinal prospective cohort Denver Family Development Study led by pediatrician and geneticist Arthur Robinson,[66] which found that in fourteen prenatally diagnosed 47,XYY boys (from high socioeconomic status families), IQ scores available for six boys ranged from 100 to 147 with a mean of 120.

[69] A November 1993 episode of the American police procedural TV series Law & Order, "Born Bad", portrays a 14-year-old XYY sociopathic murderer.

[70] The May 2007 season finale episode, "Born To Kill", of the American police procedural TV series CSI: Miami depicts a 34-year-old XYY serial killer.

[71] The false stereotype of XYY boys and men as violent criminals has also been used as a plot device in the horror films Il gatto a nove code in February 1971 (dubbed into English as The Cat o' Nine Tails in May 1971) and Alien 3 in May 1992.

His symptoms, as we and other laboratories tend to think of them, are: extremely tall stature, long limbs and strikingly long arm span, facial acne, mild mental retardation, severe mental illness (including psychosis) and aggressive, antisocial behavior with a long history of arrests, frequently beginning at an early age.On reading newspaper accounts of Richard Speck, who murdered eight Chicago student nurses in 1966, we noted all these traits and therefore concluded that Speck was a likely candidate for the XYY disorder.

Independently, a cytogenetic laboratory in Chicago confirmed this hunch, reinforcing our inclination to believe that the XYY syndrome is really coming of age.

It seems quite possible that in the XYY male, exemplified by Speck, biologists are describing in genetic terms a certain type of defective criminal who has long been explicitly recognized by the forensic psychiatrist.Dr.

He also exhibited a letter of last July 3, indicating that 100 of 101 cells in a sample of Speck's blood studied after the original tests showed the normal 46 chromosomes.