JACOBS SYNDROME (DOUBLE Y SYNDROME)

Scientifically reviewed | Last updated January 25, 2024
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XYY

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Jacob’s syndrome, or double Y syndrome (47,XYY), is a rare chromosomal disorder characterized by an additional Y chromosome in males. Characteristically, patients show above average height, but are otherwise physically inconspicuous and usually have normal fertility and IQ.

 

Also called

Jacob’s syndrome is also known as:

 

  • Double Y syndrome
  • XYY karyotype
  • XYY syndrome
  • YY syndrome

 

 

Symptoms

Symptoms of XYY syndrome vary from person to person.

 

Symptoms include:

 

  • Above average height
  • Cystic acne
  • Mildly delayed development
  • Reading and language difficulties, causing emotional disturbances and reduced frustration tolerance
  • Behavioral problems, such as explosive temper, hyperactivity, attention deficit, impulsivity, and antisocial behavior

 

Fertility and IQ are usually normal.  Scientific studies have shown that boys and men with an XYY pattern who are in a stable familial environment are not more likely to develop behavioral problems than others. Offspring of XYY males do not have an increased risk of gonosomal aneuploidies.

 

 

 

 

 

 

Frequency

XYY syndrome has an incidence of approximately 1:1,000 in male newborns.

 

 

Causes

An extra Y chromosome causes XYY syndrome.

 

 

Inheritance

XYY syndrome is not inherited. It is caused due to an error in cell division prior to conception.

 

 

Differential diagnosis

Syndromes with similar symptoms to XYY syndrome include Klinefelter syndrome, Sotos syndrome, and Marfan syndrome.

 

 

Treatment

Symptomatic treatment and early intervention can benefit affected individuals. Therapies include:

 

  • Speech therapy
  • Occupational therapy
  • Developmental therapy

 

 

References

Ross, Judith L et al. “An extra X or Y chromosome: contrasting the cognitive and motor phenotypes in childhood in boys with 47,XYY syndrome or 47,XXY Klinefelter syndrome.” Developmental disabilities research reviews vol. 15,4 (2009): 309-17. doi:10.1002/ddrr.85, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2876236/.

 

Ratcliffe, S. “Long-term outcome in children of sex chromosome abnormalities.” Archives of disease in childhood vol. 80,2 (1999): 192-5. doi:10.1136/adc.80.2.192, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1717826/pdf/v080p00192.pdf.

 

Bender, Bruce G., et al. “The Development of Four Unselected 47,XYY Boys.” Clinical Genetics, vol. 25, no. 5, 23 Apr. 2008, pp. 435–445, https://doi.org/10.1111/j.1399-0004.1984.tb02013.x

 

Valentine, G H. “The growth and development of six XYY children.” Birth defects original article series vol. 15,1 (1979): 175-90.

 

“XYY Syndrome | Male Chromosome Disorder.” Rarediseases.org, www.rarediseases.org/rarediseases/xyy-syndrome/#disease-overview-main. Accessed 12 Dec. 2023.

 

47,XYY Syndrome: MedlinePlus Genetics.” Medlineplus.gov, 2013, www.medlineplus.gov/genetics/condition/47xyy-syndrome/ Accessed 12 Dec. 2023.

 

GENES
XYY
HOW CAN YOU GET TESTED?
Step 1: Visit healthcare professional
Step 2: Sample collection (blood or buccal swab)
Step 3: Sequencing performed at our accredited laboratory
Step 4: Medical report
Step 5: Genetic counselling
FAQ

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