What are the characteristics of XYY syndrome. How is XYY syndrome diagnosed. What causes the extra Y chromosome in males. Can XYY syndrome be inherited. How does XYY syndrome affect development and behavior.

Understanding XYY Syndrome: The Basics of the Extra Y Chromosome

XYY syndrome, also known as Jacob’s syndrome or Superman syndrome, is a genetic condition that occurs when a male is born with an extra Y chromosome. Instead of the typical XY chromosome pair found in males, individuals with this syndrome have an XYY combination. This genetic alteration affects approximately 1 in 1,000 male births, making it a relatively rare occurrence.

The presence of an extra Y chromosome can lead to various physical and developmental characteristics, though it’s crucial to note that not all individuals with XYY syndrome will exhibit noticeable differences. The syndrome’s impact can vary widely from person to person, with some experiencing minimal effects while others may face more pronounced challenges.

The Genetic Basis of XYY Syndrome

To understand XYY syndrome, it’s essential to grasp the basics of human chromosomes. Typically, humans have 46 chromosomes arranged in 23 pairs. The 23rd pair, known as the sex chromosomes, determines biological sex. Females usually have two X chromosomes (XX), while males have one X and one Y chromosome (XY).

In XYY syndrome, an additional Y chromosome is present, resulting in a total of 47 chromosomes. This extra Y chromosome occurs due to a random error during cell division, specifically in the formation of sperm cells before conception.

The Origins and Prevalence of XYY Syndrome

Intriguingly, genetic research has traced the origins of XYY syndrome back approximately 100,000 years to a single male ancestor. This finding highlights the long-standing presence of this genetic variation in human populations.

Despite its ancient origins, XYY syndrome remains relatively uncommon. The prevalence of 1 in 1,000 male births means that while not exceedingly rare, it’s still considered an uncommon genetic condition. This prevalence rate underscores the importance of awareness and understanding among healthcare professionals and the general public.

Is XYY Syndrome Hereditary?

A common question regarding XYY syndrome is whether it can be inherited. Interestingly, the condition is not typically passed down from father to son. The extra Y chromosome results from a spontaneous error in sperm cell formation, known as nondisjunction, rather than being inherited from a parent with the syndrome.

This means that fathers with XYY syndrome do not have an increased risk of passing the condition to their children. Each new case of XYY syndrome is generally the result of a new genetic event occurring during sperm cell development.

Physical Characteristics and Symptoms of XYY Syndrome

The physical manifestations of XYY syndrome can vary significantly among affected individuals. It’s important to emphasize that many boys and men with XYY syndrome may not display any obvious physical differences compared to those without the condition.

However, some common physical characteristics associated with XYY syndrome include:

• Increased height (often taller than average)
• Larger head circumference
• Enlarged testicles
• Increased distance between certain body parts
• Mild facial features, such as widely spaced eyes or a broader nose

Developmental and Behavioral Aspects of XYY Syndrome

Beyond physical characteristics, XYY syndrome can sometimes impact developmental and behavioral aspects. These may include:

• Delayed speech and language development
• Mild learning difficulties, particularly in reading and language skills
• Attention deficit hyperactivity disorder (ADHD) in some cases
• Increased risk of behavioral issues, such as impulsivity or difficulty with social interactions
• Slightly lower IQ compared to family members, though usually within the normal range

It’s crucial to note that these characteristics are not universal, and many individuals with XYY syndrome lead fulfilling lives without significant challenges.

Diagnosing XYY Syndrome: Methods and Challenges

Diagnosing XYY syndrome can be challenging, primarily because many affected individuals may not display obvious symptoms that would prompt genetic testing. In many cases, the condition goes undiagnosed throughout a person’s life.

However, there are several methods for diagnosing XYY syndrome:

Prenatal Diagnosis

XYY syndrome can be detected before birth through prenatal testing methods such as:

• Amniocentesis: A procedure that involves collecting a sample of amniotic fluid surrounding the fetus
• Chorionic villus sampling (CVS): A test that involves removing tissue samples from a portion of the placenta

These tests can reveal the presence of an extra Y chromosome in the developing fetus.

Postnatal Diagnosis

After birth, XYY syndrome may be diagnosed through:

• Karyotype analysis: The most common test used to detect the presence of an extra Y chromosome
• Clinical evaluation: A physician may suspect XYY syndrome based on physical characteristics or developmental concerns
• Genetic testing: Advanced genetic tests can confirm the presence of the extra Y chromosome

Often, the diagnosis is made when investigating learning difficulties, developmental delays, or behavioral issues in childhood or adolescence.

Treatment and Management of XYY Syndrome

While there is no cure for XYY syndrome, many individuals with the condition lead healthy, fulfilling lives without the need for significant medical intervention. However, some may benefit from supportive care and interventions tailored to their specific needs.

Educational Support

For those experiencing learning difficulties, educational support may include:

• Special education services
• Speech and language therapy
• Individualized education plans (IEPs)
• Tutoring or additional academic support

Behavioral Interventions

If behavioral issues are present, interventions may involve:

• Behavioral therapy
• Social skills training
• Counseling or psychotherapy
• In some cases, medication for conditions like ADHD

Medical Management

Regular medical check-ups are important to monitor for any potential health issues associated with XYY syndrome, such as:

• Dental problems (due to possible dental abnormalities)
• Asthma (which may be more common in individuals with XYY syndrome)
• Monitoring of growth and development

Living with XYY Syndrome: Long-term Outlook and Quality of Life

The long-term prognosis for individuals with XYY syndrome is generally positive. Many men with the condition lead normal, healthy lives and are unaware of their extra Y chromosome. They can expect to have typical life expectancies and are fully capable of having families and successful careers.

Fertility and Family Planning

Contrary to what some might assume, XYY syndrome does not typically affect fertility. Men with the condition can father children, and as mentioned earlier, they do not have an increased risk of passing the syndrome to their offspring.

Academic and Professional Success

While some individuals with XYY syndrome may face learning challenges, many excel academically and professionally. With appropriate support and interventions when needed, boys with XYY syndrome can perform well in school and pursue higher education.

Social and Emotional Well-being

Most individuals with XYY syndrome develop normal social relationships and lead fulfilling personal lives. However, some may benefit from support in developing social skills or managing emotional regulation if they experience challenges in these areas.

Research and Future Directions in XYY Syndrome

Ongoing research into XYY syndrome continues to expand our understanding of this genetic condition. Current areas of focus include:

• Investigating the specific genes on the Y chromosome that may contribute to XYY syndrome characteristics
• Exploring potential links between XYY syndrome and other neurodevelopmental conditions
• Developing more targeted interventions to support individuals with XYY syndrome
• Improving diagnostic techniques to enable earlier detection and intervention

As research progresses, it’s likely that our understanding of XYY syndrome will continue to evolve, potentially leading to improved management strategies and support for affected individuals.

Raising Awareness and Combating Stigma Associated with XYY Syndrome

One of the challenges faced by individuals with XYY syndrome and their families is the lack of awareness and potential stigma associated with the condition. Efforts to increase public understanding and promote acceptance are crucial for ensuring that those with XYY syndrome receive appropriate support and opportunities.

Education and Advocacy

Initiatives aimed at educating healthcare providers, educators, and the general public about XYY syndrome can help to:

• Improve early detection and intervention
• Reduce misconceptions and stereotypes
• Promote inclusive practices in schools and workplaces
• Encourage supportive communities for individuals with XYY syndrome and their families

Support Groups and Resources

Various organizations and support groups exist to provide information, resources, and community for those affected by XYY syndrome. These groups can offer valuable emotional support, practical advice, and opportunities for connection with others who share similar experiences.

By fostering a more informed and accepting society, we can ensure that individuals with XYY syndrome have every opportunity to thrive and reach their full potential.

What Is XYY Syndrome? Symptoms, Causes, Diagnosis, Treatment, and Prevention

How Is XYY Syndrome Diagnosed?

Since there is often no medical reason to test for XYY syndrome, the diagnosis is commonly never made.

With that said, a diagnosis can be made before birth while a baby is still in the mother’s womb with amniocentesis, which involves gathering a sample of fluid that surrounds the fetus or through chorionic villus sampling (CVS), the removal of tissue samples from a portion of the placenta. (3)

These tests can reveal if an extra Y chromosome is present.

If prenatal diagnosis is not done, a physician can diagnose XYY syndrome on a person by performing a clinical evaluation, patient history, and specialized tests, such as a karyotype, which is the most common test, to detect the presence of an extra Y chromosome. (3)

Boys may also be diagnosed because of learning problems, developmental delay, or behavioral issues. (3)

Prognosis of XYY Syndrome

Those with XYY can expect to have a good long-term outlook. Boys can do well in school and in building relationships, while adults with the syndrome can have successful careers and families. (4)

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What Are YY Chromosomes? When Superman Syndrome Occurs

Written by WebMD Editorial Contributors

• What Causes YY Chromosomes to Occur?
• What Are the Physical Characteristics of YY Chromosomes?
• What Are the Symptoms of YY Chromosomes?
• How Is YY Diagnosed?

‌Although genetics are hereditary, a phenomenon in genetic alterations occurs when male babies receive an extra Y chromosome in each of their cells, resulting in an XYY combination. The syndrome is commonly known as Jacob’s syndrome, Superman syndrome, XYY karyotype, XYY syndrome, YY syndrome, and 46,XY/47,XYY mosaicism. The genetic alteration occurs in one out of 1,000 male babies and can be traced back 100,000 years to one male ancestor.

The usual number of chromosomes inside every cell of your body is 46 total chromosomes, or 23 pairs. You inherit half of your chromosomes from your biological mother, and the other half from your biological father.

The first 22 pairs of chromosomes are called autosomes. The 23rd pair of chromosomes are known as the sex chromosomes, because they decide if you will be born male or female. Females have two X chromosomes, while males have one X and one Y chromosome. 

The Superman syndrome occurs when males receive an extra Y chromosome at conception, creating an XYY combination. ‌This results in a male baby born with the XYY syndrome, which is a random occurrence due to the sperm cell’s formation before conception occurs. ‌

Known as nondisjunction, this is an error in the sperm cell’s division. The resulting child will have an extra Y chromosome in every cell of his body. However, it’s not a hereditary trait — fathers with XYY chromosomes don’t pass on this syndrome to their sons.

The physical characteristics in a person with an extra Y chromosome have broad variations. It’s important to remember that not all boys born with XYY syndrome will demonstrate observable differences. How your physical body functions is a result of the instructions encoded in your genes. You have an inherently unique genetic makeup that creates your genotype.‌

Your genotype combines with environmental factors to determine your physical body structure and function known as the phenotype. The entire embodiment of a full set of chromosomes results in your karyotype.‌

Physical features associated with this syndrome may include:

• Large testes 
• ‌Large head 
• Increased distance between two body parts, typically the eyes
• Increased belly fat
• Large teeth
• Flat feet 
• Fifth fingers that curve inward
• Atypical side-to-side curvature of the spine 
• Tall stature ‌

It’s important to keep in mind that sometimes there’s an absence of any unusual phenotype traits, although above-average height is a common result. Studies reveal that men with the syndrome carry an extra copy of the SHOX gene, which is found on a sex chromosome. The SHOX gene is also responsible for skeleton development, particularly in the growth and maturation of the limbs.‌

A majority of men with XYY syndrome are fertile, with typical testosterone levels and sexual development. However, some boys may develop testicular failure that leads to fertility problems.

The XYY syndrome correlates with certain physical conditions and disabilities in males with the extra Y chromosome. Symptoms range from mild to severe, so the physical symptoms can go undetected:

• Asthma
• ‌Autism spectrum disorder
• Seizures 
• Hand tremors
• Involuntary movements
• Low muscle tone hypotonia
• Delayed development of motor skills (such as sitting and walking)
• Speech delay
• Difficulty with reading and writing
• Dental problems
• Autism spectrum disorder (mildly)
• Attention deficit disorder, ADHD
• Anxiety 
• Mood disorders
• Depression
• Infertility

‌It’s important to note that intellectual disabilities are not a typical sign. Individuals with XYY syndrome are also able to produce children with typical karyotypes.

Genetic testing for XYY syndrome can be conducted in prenatal tests or anytime throughout the boy’s life. Upon diagnosis, the syndrome can be managed through specialized education and therapies, such as when developmental delays in speech and mobility are apparent. Two commonly ordered tests are:

1. Karyotype test, which detects all the chromosomes in a cell
2. Chromosomal microarray test, which detects extra or missing chromosomes

There are also prenatal tests that can confirm a diagnosis of the XYY syndrome, such as an amniocentesis or chorionic villus sampling, which pregnant women can have to detect potential genetic problems with their unborn child. It’s speculated that a portion of the male population who have Jacob’s syndrome never receive diagnosis due to the lack of symptoms.

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Jacob’s syndrome – XXY

XYY-syndrome is a chromosomal disease that is characteristic only for men. The carrier of the syndrome has an additional Y-chromosome, the total chromosome set is 44 autosomes and three sex chromosomes. Outwardly, males with an extra Y chromosome usually do not have significant differences from normal ones, but they may have a number of features.

Find out with 99% accuracy about the risk of Jacob’s syndrome and other chromosomal abnormalities, as well as the sex of the fetus, from 9weeks of pregnancy, just donating blood from a vein. Learn more about the NIPT test.

Signs of Jacob’s Syndrome

The presence of a second Y-chromosome in most cases does not lead to any physical abnormalities. At the same time, many men with XYY syndrome have one or more features. They are of normal height at birth, but often grow faster during childhood. On average, as an adult, the carrier is higher than 75% of men of the same age. Some men with XYY syndrome have slight incoordination that can make them appear clumsy. Fertility is most often not impaired, usually such men are heterosexual and have normal sexual function. Nevertheless, cases of a significant decrease in fertility, up to infertility, are described. A small number of carriers also have elevated levels of sex hormones associated with spermatogenesis, which can lead to infertility due to impaired sperm production. It is not known how high the incidence of infertility in men with XYY syndrome is. IQ is within the normal range, but often slightly lower than that of siblings. Approximately half of the carriers have learning problems, in particular, there may be speech and reading disorders. There may be an increased risk of behavioral problems such as hyperactivity disorder, men with XYY syndrome are often impulsive and emotionally immature.

Prenatal diagnosis

1) Invasive tests (amniocentesis, chorionic biopsy) are mainly indicated for women who have an increased risk of having a baby with Jacob’s syndrome, for example, patients whose age is over 35 years or with poor results of non-invasive tests: ultrasound and tests. Invasive diagnostic methods are highly accurate, however, given the risk of complications, they are not suitable for mass conduction by all pregnant women, but are carried out only for special indications.

2) Non-invasive technologies so-called screenings. Screening is a comprehensive study of pregnant women for the presence of chromosomal abnormalities in the fetus. Several signs have been identified that indicate a high risk of the presence of the disease, which can be detected by ultrasound of the fetus (absence of the nasal bone, increased thickness of the collar space, insufficient length of the femur and humerus, and other features). In combination with ultrasound, there is a biochemical analysis of the mother’s blood for hormones such as free beta-hCG and PAPP-A. The obtained data on biochemical markers are analyzed in conjunction with the results of an ultrasound examination, and the result of the entire screening is a calculation of the risk of having a chromosomal abnormality in the fetus.

However, when using standard tests for Jacob’s syndrome, only 3% of women referred for invasive diagnosis actually confirm the presence of the disease. At the same time, false-negative results are not excluded, when screening shows a low risk, and the child is born with a chromosomal pathology.

Non-invasive examination method (NIPT test)

• 99% accuracy, which is much more accurate than classical diagnostics (ultrasound and biochemical screening)
• is completely safe, unlike invasive methods – to take material for analysis, you just need to take blood from a vein of a pregnant woman.
• in early pregnancy: the test can be performed as early as the 9th week of pregnancy.

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Extra X and Y chromosomes – NIPT Prenetics

Contents

Genetic information is contained in each cell in the form of formations located in the nucleus – chromosomes. At the same time, a person has a double (diploid) set, that is, the karyotype is represented by 23 pairs of chromosomes, and the chromosomes themselves are normally 46.

The normal chromosome formula can be written as 44+XX or 46(XX) for women and 44+XY or 46(XY) for men. 44 chromosomes or more correctly 22 pairs – autosomes – they are the same for both sexes, and the 23rd pair is called sex chromosomes, since they determine the sex of the unborn child.

If the 23rd pair is XX, then the gender is female, if XY, then male.

Changes in the total number of chromosomes, or normal karyotype, are called aneuploidies. Chromosomes may be larger or smaller than normal.

Types of aneuploidies

Autosomal

Changes in the number of autosomes occur in different pairs of chromosomes. Most often, trisomy occurs in the following pairs of chromosomes, that is, situations where instead of two chromosomes there are three. Trisomy 21 is Down syndrome, trisomy 18 is Edwards syndrome, and trisomy 13 is Patau syndrome. These types of chromosomal pathologies can be combined with the birth of a live fetus, but with multiple severe malformations, and trisomy 18 and 13 are characterized by very poor survival of such children, and trisomy 21, despite developmental malformations, allows a person to live a fairly long time. Information on the main trisomies is in the relevant articles on our website.

In general, there are much more aneuploidies in autosomes – they can also occur in other pairs of chromosomes, tetrasomies or combinations of trisomies in several pairs at the same time are much less common, but they are all fatal, and even at the earliest stages of pregnancy, spontaneous termination occurs.

Extra X and Y chromosomes in pair 23

Extra chromosomes in pair 23 or extra sex chromosomes form the characteristic clinical signs, however, according to the degree of their manifestations, additional sex chromosomes are accompanied by much milder defects. At the same time, albeit very rarely, tetra-, penta- and more chromosomes can occur, which leads to an increase in the severity of developmental defects.

The most common variants of additional Y and X chromosomes will be considered below.

XXY syndrome – Klinefelter’s syndrome

In addition to this classic variant, there are other more rare combinations with an increase in X and Y chromosomes.

This syndrome of aneuploidy for sex chromosomes is characterized by a violation of the development of the male body in the direction of its feminization, that is, with a predominance of female features. It is important that before the onset of puberty, in some cases, it may not be recognized at all, it can only be suspected by a number of indirect signs.

After the onset of puberty, the manifestations become characteristic – high growth, while the female type of figure with a wide pelvis and narrow shoulders. The voice can remain practically unchanged – it does not mutate, does not become masculine. Characteristic is the underdevelopment of the external genital organs and erectile dysfunction. At the same time, female-type hair growth is noted. There is a lower level of libido in such men, very often infertility occurs due to impaired development of spermatozoa. In the intellectual sphere, some lag is possible.

XYU syndrome — “superman” syndrome

Despite the name, such people do not have any superpowers, as well as excessive aggression and excessive potential in the intimate sphere.

The main features are shorter stature and earlier onset of puberty. Masculinization occurs earlier than among peers, excessive hair growth and earlier baldness are more common. In the intellectual sphere, there is a slight lag behind the population, but this is due to the fact that such children from early childhood have increased distractibility, lability of attention, restlessness, they learn the material more difficult, it is from school that the specified lag is observed. There may be some decrease in the ability to conceive. Although the vast majority of patients with XY syndrome are not detected clinically, but with various genetic tests, that is, “in passing”

Syndrome XXX – “superwoman” syndrome

Similar to the previous one, it can be an “accidental finding” during genetic studies, outwardly it has minimal manifestations.

Of the most pronounced – a slight decrease in the ability to bear, due to a higher percentage of spontaneous interruptions, minimal manifestations in the reproductive and intellectual spheres can be observed.

Additional Y and X chromosomes with minimal manifestations

In this case we are talking about the so-called “mosaicism”. This is a phenomenon when a certain part of the cells of the body contains some kind of aneuploidy, and the rest of the cells are described by a normal chromosome formula. This situation occurs if the chromosomal mutation did not occur during the fertilization of the egg, but in the early stages of zygote division. The later this happens, the smaller part of the cells has karyotype disorders and the less clinical manifestations. Very often, such mosaicism is found only in genetic studies.

Diagnosis of various types of aneuploidy.

The only reliable way of early intrauterine diagnosis of chromosomal abnormalities in the fetus is a genetic study. Confirmation of the diagnosis, suspected on the basis of the risks identified during screening, is carried out with an invasive sampling of material, which requires clearly justified indications for carrying out.

With the help of the non-invasive prenatal test Prenetix, it is possible to examine fetal DNA in the venous blood of the expectant mother from the 10th week of pregnancy. The reliability and specificity of the method allows us to classify Prenetix as an expert-level screening, which significantly increases the information content of traditional first trimester screening.