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Disease Profile

48,XXYY syndrome

Prevalence
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.

Unknown

US Estimated

Europe Estimated

Age of onset

Infancy

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ICD-10

Q98.8

Inheritance

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

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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.

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X-linked
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.

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

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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.

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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.

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Not applicable

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Other names (AKA)

48,XXYY Klinefelter syndrome; 48,XXYY variant of Klinefelter's syndrome; XXYY syndrome

Summary

48,XXYY syndrome is a chromosomal condition, characterized by the presence of an extra X and Y chromosome in males, that causes medical and behavioral problems. 48,XXYY can be considered a variant of Klinefelter syndrome. Individuals with 48,XXYY are usually considerably tall with small testes that do not function normally leading to infertility. In addition, affected individuals have behavioral problems such as anxiety, aggressiveness, problems communicating, hyperactivity, depression, as well as general learning disabilities and intellectual impairment. Other medical probelms can include congenital heart defects, bone abnormalities, tremor, obesity, type 2 diabetes and/or respiratory problems.[1][2] Patients have an essentially normal life expectancy but require regular medical follow-up.[2]

Symptoms

48,XXYY affects various body systems including disruption of male sexual development. Adolescent and adult males with this condition typically have small testes that do not produce enough testosterone, which is the hormone that directs male sexual development. A shortage of testosterone during puberty can lead to reduced facial and body hair, poor muscle development, low energy levels, and an increased risk for breast enlargement (gynecomastia). Because their testes do not function normally, males with 48, XXYY syndrome have an inability to father children (infertility).

48,XXYY syndrome can affect other parts of the body as well. Males with 48,XXYY syndrome are often taller than other males their age. They tend to develop a tremor that typically starts as a young adult and worsens with age. Dental problems are frequently seen with this condition; they include delayed appearance of the primary (baby) or secondary (adult) teeth, thin tooth enamel, crowded and/or misaligned teeth, and multiple cavities. As affected males get older, they may develop a narrowing of the blood vessels in the legs, called peripheral vascular disease. Peripheral vascular disease can cause skin ulcers to form. Affected males are also at risk for developing a type of clot called a deep vein thrombosis (DVT) that occurs in the deep veins of the legs. Additionally, males with 48,XXYY syndrome may have flat feet (pes planus), elbow abnormalities, allergies, asthma, type 2 diabetes, seizures, and congenital heart defects.[3][1]

Most males with 48,XXYY syndrome have some degree of difficulty with speech and language development. Learning disabilities, especially reading problems, are very common in males with this disorder. Affected males seem to perform better at tasks focused on math, visual-spatial skills such as puzzles, and memorization of locations or directions. Some boys with 48,XXYY syndrome have delayed development of motor skills such as sitting, standing, and walking that can lead to poor coordination. Affected males have higher than average rates of behavioral disorders, such as attention deficit hyperactivity disorder (ADHD); mood disorders, including anxiety and bipolar disorder; and/or autism spectrum disorders, which affect communication and social interaction.[3]

Cause

48,XXYY syndrome is a condition related to the X and Y chromosomes (the sex chromosomes). People normally have 46 chromosomes in each cell. Two of the 46 chromosomes, known as X and Y, are called sex chromosomes because they help determine whether a person will develop male or female sex characteristics. Females typically have two X chromosomes (46,XX), and males have one X chromosome and one Y chromosome (46,XY). 48,XXYY syndrome results from the presence of an extra copy of both sex chromosomes in each of a male's cells (48,XXYY). Extra copies of genes on the X chromosome interfere with male sexual development, preventing the testes from functioning normally and reducing the levels of testosterone. Many genes are found only on the X or Y chromosome, but genes in areas known as the pseudoautosomal regions are present on both sex chromosomes. Extra copies of genes from the pseudoautosomal regions of the extra X and Y chromosome contribute to the signs and symptoms of 48,XXYY syndrome; however, the specific genes have not been identified.[3]

Organizations

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.
      • PubMed is a searchable database of medical literature and lists journal articles that discuss 48,XXYY syndrome. Click on the link to view a sample search on this topic.

        References

        1. Chen H. Klinefelter syndrome. Medscape Reference. 2018; https://emedicine.medscape.com/article/945649-overview.
        2. Corsini C, Sarda P. 48,XXYY. Orphanet. May 2011; https://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=EN&Expert=10. Accessed 5/2/2012.
        3. US National Library of Medicine. 48,XXYY syndrome. Genetics Home Reference. January 2010; https://ghr.nlm.nih.gov/condition/48xxyy-syndrome.

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