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Disease Profile

47, XYY syndrome

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

1-5 / 10 000

US Estimated

Europe Estimated

Age of onset

All ages





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

YY syndrome; XYY syndrome; XYY Karyotype;


Chromosome Disorders; Congenital and Genetic Diseases


47, XYY syndrome is a syndrome (group of signs and symptoms) that affects males. For some males with this syndrome, signs and symptoms are barely noticeable. For others, signs and symptoms may include learning disabilities, speech delay, low muscle tone (hypotonia), and being taller than expected.[1][2]

47, XYY syndrome is caused by having an extra copy of the Y chromosome in every cell of the body.[1] The syndrome is usually not inherited. Diagnosis can be made based on prenatal tests, or it may occur during childhood or adulthood if a male has signs or symptoms of the disease. Management may include special education as well as intervention or therapies for developmental delays.[2]


The signs and symptoms of 47, XYY syndrome can range from barely noticeable to more severe. It is thought that some males with 47, XYY syndrome may never be diagnosed because the signs and symptoms may not be noticeable.[2] For other males, signs and symptoms such as low muscle tone (hypotonia) and/or speech delay may begin in late infancy or early childhood. Some boys with 47, XYY syndrome may have difficulty in certain subjects in school such as reading and writing. However, boys with this syndrome do not typically have intellectual disability.[1][3]

Other signs and symptoms of 47, XYY syndrome may include asthma, dental problems, and acne.[2][3][4] Boys with the syndrome don’t typically have physical features different from most people, but they may be taller than expected. These boys are not expected to have differences in the appearance of the sex organs (genitalia). Some males with 47, XYY syndrome have behavioral differences such as autism spectrum disorder (usually on the milder end) or attention deficit hyperactivity disorder (ADHD). Boys with 47, XYY syndrome are also at an increased risk to have anxiety or mood disorders.[2]

Most boys with 47, XYY syndrome go through normal sexual development, and fertility is expected to be normal. However, some boys with the syndrome may develop testicular failure (when the testes can’t produce sperm or testosterone), which can lead to problems with fertility.[2][5][6] 

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
80%-99% of people have these symptoms
Delayed speech and language development
Deficiency of speech development
Delayed language development
Delayed speech
Delayed speech acquisition
Delayed speech development
Impaired speech and language development
Impaired speech development
Language delay
Language delayed
Language development deficit
Late-onset speech development
Poor language development
Speech and language delay
Speech and language difficulties
Speech delay

[ more ]

Low-set ears
Low set ears
Lowset ears

[ more ]

Malar flattening
Zygomatic flattening
Motor delay
Tall stature
Increased body height
30%-79% of people have these symptoms
Attention deficit hyperactivity disorder
Attention deficit
Attention deficit disorder
Attention deficit-hyperactivity disorder
Attention deficits
Childhood attention deficit/hyperactivity disorder

[ more ]

Congenital stationary night blindness
Night blindness since birth
Finger clinodactyly
Wide-set eyes
Widely spaced eyes

[ more ]

Impaired social interactions
Impaired social interaction
Poor social interactions

[ more ]

Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific

[ more ]

Increased size of skull
Large head
Large head circumference

[ more ]

Neonatal hypotonia
Low muscle tone, in neonatal onset
Specific learning disability
5%-29% of people have these symptoms
Abnormality of brainstem morphology
Abnormal shape of brainstem
Absent sperm in semen
Cerebellar dysplasia
Undescended testes
Undescended testis

[ more ]

Dysgenesis of the cerebellar vermis
Too much cerebrospinal fluid in the brain
Increased circulating gonadotropin level
Elevated gonadotropins
Elevated serum gonadotropins
Gonadotropin excess

[ more ]

Increased serum testosterone level
Large testis
Male infertility
Short penis
Small penis

[ more ]

Low sperm count


47, XYY syndrome is caused by having an extra copy of the Y chromosome in each cell of the body.[1] The Y chromosome is one of the sex chromosomes, and the other sex chromosome is called the X chromosome. Most people have two sex chromosomes, with girls having two X chromosomes, and boys having one X and one Y chromosome.

Boys with 47, XYY syndrome have one X chromosome and two Y chromosomes in each cell of the body. This typically happens due to a random event when a sperm cell is formed that causes the sperm cell to have two Y chromosomes. When a sperm that has two Y chromosomes fertilizes an egg (which has an X chromosome), the resulting baby will be a male with two Y chromosomes and one X chromosome.[1] It is also possible that a similar random event could occur very early in an embryo’s development. This can produce a boy who has some cells that have two sex chromosomes and some cells that have an extra Y chromosome.[1]

It is not fully understood why an extra copy of the Y chromosome causes the features associated with 47, XYY syndrome. It is thought that the tall stature seen in some males with the syndrome is caused by having an extra copy of a gene that is located on the sex chromosomes called the SHOX gene. This gene provides instructions to the body to control growth of the bones. People who have an extra copy of the Y chromosome also have an extra copy of the SHOX gene, which could explain why they may be taller than expected. Another gene that is thought to cause the signs and symptoms of 47, XYY syndrome is called NLGN4Y. This gene is located on the Y chromosome and provides instructions to the body that helps form connections between the cells in the brain. It is thought that having an extra copy of this gene may cause the learning problems associated with 47, XYY syndrome.[2]


47, XYY syndrome may be suspected when a doctor observes signs and symptoms that can be associated with the syndrome such as low muscle tone (hypotonia), speech delay, or learning problems in school. A doctor may then order testing to see if there is a genetic explanation for the signs and symptoms. Tests that may be ordered include:[2]

  • Karyotype: a test that is used to view all the chromosomes in a cell
  • Chromosomal microarray: a test that looks for extra or missing chromosomes or pieces of chromosomes

In some cases, 47, XYY syndrome may be suspected prenatally based on routine screening tests. A diagnosis can be confirmed with prenatal tests such as an amniocentesis or chorionic villus sampling (CVS).[2]

It is thought that some people who have 47, XYY syndrome are never diagnosed because they do not have severe signs or symptoms of the syndrome.[2] 


The signs and symptoms of 47, XYY syndrome can be managed with a variety of therapies. Occupational therapy may be recommended for infants and young boys who have low muscle tone (hypotonia), and speech therapy may be recommended for boys who have speech delay. Boys with 47, XYY syndrome may be in special education at school, or they may have extra help in some classes.[2][5]

Other management options for boys with 47, XYY syndrome may include behavioral therapy or medications for boys with attention deficit hyperactivity disorder (ADHD) or behavioral problems. If autism spectrum disorder is present, applied behavioral analysis (ABA) therapy may be recommended.[2] In some cases, hormonal therapy may be used.[7]


Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

    Learn more

    These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

    Where to Start

      In-Depth Information

      • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
      • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
      • PubMed is a searchable database of medical literature and lists journal articles that discuss 47, XYY syndrome. Click on the link to view a sample search on this topic.


        1. 47,XYY syndrome. Genetics Home Reference. January 2009; https://ghr.nlm.nih.gov/condition/47xyy-syndrome.
        2. Ross J and Bishop D. XYY. Unique. 2014; https://www.rarechromo.org/information/Chromosome_Y/XYY%20FTNW.pdf.
        3. Lenroot RK. XYY Syndrome. National Organization for Rare Disorders. 2012; https://rarediseases.org/rare-diseases/xyy-syndrome/.
        4. Schedit L, Sanabe ME, and Diniz MB. Oral, physical, and behavioral aspects of patient with chromosome 47, XYY syndrome. Journal of the Indian Society of Pedodontics and Preventive Dentistry. October-December 2015; 33(4):347-350. https://www.ncbi.nlm.nih.gov/pubmed/26381641.
        5. Frequently Asked Questions: X and Y Chromosome Variations. The Association for X and Y Chromosome Variations (AXYS). https://genetic.org/variations/faq/.
        6. Borjian Boroujeni P, Sabbaghian M, Vosough Dizaji A, Zarei Moradi S, Almadani N, Mohammadpour Lashkari F, Zamanian MR, and Mohseni Meybodi A. Clinical aspects of infertile 47,XYY patients: a retrospective study. Human Fertility. July 18, 2017; https://www.ncbi.nlm.nih.gov/pubmed/28715980.
        7. Samango-Sprouse C, Stapleton EJ, Lawson P, Mitchell F, Sadeghin T, Powell S, and Gropman AL. Positive effects of early androgen therapy on the behavioral phenotype of boys with 47,XXY. Am J Med Genet C Semin Med Genet. June 2015; 169(2):150-157. https://www.ncbi.nlm.nih.gov/pubmed/25939399.

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