XYY syndrome is also called Jacob's syndrome and 47,XYY syndrome.  It is a chromosomal disorder caused by the presence of an extra Y chromosome in men. Learn about XYY syndrome treatment from experts at Meri Sehat.

XYY Syndrome

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Iqra Mazhar

Overview

XYY Syndrome (also known as Jacob&#39;s syndrome, YY Syndrome, and Superman syndrome) is a rare chromosomal disorder that affects males. In this disorder, male babies receive an extra Y chromosome in their cells, creating a configuration of XYY<a href="#accordion">[1]</a>.

Normally, males have an X and a Y chromosome, whereas, in this disorder, males have 1 X chromosome and 2 Y chromosomes. Individuals with XYY syndrome have a tall height along with learning disabilities and behavioral issues, such as explosive temper and impulsivity<a href="#accordion">[2]</a>. These individuals usually have a normal IQ, but it may be 10 to 15 points lower compared to their siblings.&nbsp;

Individuals with Jacob&#39;s syndrome often have difficulty learning especially in the first few years of school and they may need additional tutoring or speech therapy.&nbsp;

However, males with Jacob&#39;s syndrome have normal sexual development and do not have any fertility issues and they live healthy and normal lives<a href="#accordion">[2]</a>.

<div>&nbsp;</div>

XYY syndrome is a relatively rare condition as it affects every 1 out of 1000 males<a href="#accordion">[3]</a>. Each day in the United States, 5 -10 children with XYY or Jacob&#39;s syndrome are born<a href="#accordion">[4]</a>.&nbsp;

This disorder can go largely unnoticed due to absence of any troubling sign or symptom for which treatment could be sought. Therefore, many cases of XYY syndrome either remain undiagnosed or are misdiagnosed.&nbsp;

Since the diagnosis is often delayed, the average age of diagnosing Jacob&#39;s syndrome is 17 years<a href="#accordion">[3]</a>. It is estimated that around 85% of males with 47 chromosomes and XYY syndrome remain undiagnosed<a href="#accordion">[3]</a>.

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Signs And Symptoms

The clinical presentation of XYY syndrome isn&#39;t very specific. Most of the time this condition remains undiagnosed due to subtle signs and symptoms. Following clinical picture is seen in individuals with Superman syndrome<a href="#accordion">[1][2][4][5]</a>:&nbsp;

&nbsp;

<ul>
	<li>Tall height &ndash; up to 6 feet and 3 inches on average</li>
	<li>Severe cystic acne during teenage years</li>
	<li>Increase in belly fat</li>
	<li>Large head (macrocephaly)</li>
	<li>Large teeth (macrodontia)</li>
	<li>Large testis</li>
	<li>Flat feet also known as pes planus</li>
	<li>Fifth finger is usually curved inward</li>
	<li>Eyes are widely spaced</li>
	<li>Abnormal curvature of the spine (scoliosis)</li>
	<li>Muscle weakness or decrease in muscle tone (hypotonia)</li>
	<li>Intelligence &ndash; 10-15 points lower than their siblings&rsquo; IQ&nbsp;</li>
	<li>Developmental delays</li>
	<li>Learning disabilities&nbsp;</li>
	<li>Speech delays</li>
	<li>Language problems&nbsp;</li>
	<li>Difficulty in reading (dyslexia)</li>
</ul>

&nbsp;

Some cases of Jacob&#39;s syndrome are associated with behavioral problems, such as hyperactivity, defiant actions, impulsive response, antisocial behavior, and an explosive temper. They are more likely to develop attention deficit hyperactivity disorder (<a href="https://www.merisehat.pk/disease/attention-deficit-hyperactivity-disorder-adhd" target="_blank">ADHD</a>)<a href="#accordion">[2]</a>.

Additionally, individuals with XYY syndrome are also at a slightly increased risk of developing autism spectrum disorder. <a href="https://www.merisehat.pk/disease/autism" target="_blank">Autism </a>is a neurological and developmental disorder<a href="#accordion">[4]</a>. They are also at risk of developing <a href="https://www.merisehat.pk/disease/asthma" target="_blank">asthma </a>and seizures<a href="#accordion">[5]</a>.

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Causes

Males who have XYY syndrome have an extra copy of the Y chromosome in almost all of their cells in the body.&nbsp;Normally, people have 46 chromosomes in each cell which are then made into 23 pairs. One chromosome from each pair is inherited from the mother and the other from the father. The 22 pairs of chromosomes define the physical characteristics of an individual, such as their eye color and height, while the 23rd pair of chromosomes is referred to as the sex chromosomes that determine the sex at the time of birth.

If the baby has 2 X chromosomes &ndash; 1 from each parent &ndash; then it will be a female baby at birth. On the contrary, when a baby gets 1 X chromosome from the mother and one Y chromosome from the father, then the resulting XY configuration means it will be a male<a href="#accordion">[5]</a>. However, due to an error an extra Y chromosome joins the pair of XY chromosomes in males with XYY syndrome. That is, they have a total of 47 chromosomes at the time of conception.&nbsp;

The 2 Y chromosomes are the reason why these individuals have a tall height. However, the production of the male hormone, testosterone, remains unaffected as a result of which sexual development is normal and no fertility issues are reported in this disorder in the majority of the cases.

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Diagnosis

Screening is a way to diagnose the condition at a very early stage that is before the disease becomes evident clinically.&nbsp;Prenatal testing is a way to diagnose any chromosomal abnormality in the child even before the child is born.

Chorionic villus sampling and amniocentesis are two prenatal tests that are performed on the pregnant female by taking a sample of the fluid surrounding the fetus in the womb to detect chromosomal disorders, such as Jacob&#39;s syndrome or XYY syndrome. These tests are quite helpful since most cases of Jacob&#39;s syndrome remain undiagnosed due to subtle symptoms<a href="#accordion">[1]</a>.

&nbsp;

Once the child is born, doctors diagnose XYY syndrome by taking a blood sample from the child and testing it for the presence of an extra chromosome. The following tests are performed for this purpose<a href="#accordion">[1]</a>:

&nbsp;

<ul>
	<li>Karyotype Test: This test looks for all the chromosomes in the cells.</li>
</ul>

&nbsp;

<ul>
	<li>Chromosomal Microarray Test: This test detects any missing or extra chromosomes within the cell.</li>
</ul>

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Treatment

There is no cure for Jacob&#39;s syndrome since the error lies in the chromosome configuration. However, XYY syndrome treatment is targeted to manage the symptoms of these individuals. The following help manage XYY syndrome<a href="#accordion">[2]</a>:

&nbsp;

<ul>
	<li>Speech Therapy And&nbsp;Learning Assistance</li>
</ul>

Since these individuals have difficulty with learning and reading along with speech problems, speech therapies, and learning assistance should be provided to counter these issues.&nbsp;

Additionally, these individuals usually respond well to interventions, such as tutoring and speech therapy, and within a few years, they can overcome these learning and speech difficulties.&nbsp;

&nbsp;

<ul>
	<li>Physical Therapy&nbsp;</li>
</ul>

Individuals with XYY syndrome have muscle weakness and they greatly benefit from physical therapy as it builds strength.&nbsp;

&nbsp;

<ul>
	<li>Prescription Medication For Cystic Acne</li>
</ul>

Since these individuals socially struggle due to their appearance, treatment for severe cystic acne would restore their self-esteem.&nbsp;

&nbsp;

<ul>
	<li>Treatment And Therapy For ADHD/ASD</li>
</ul>

Individuals with attention deficit hyperactivity disorder or autism spectrum disorder, need to be provided with required therapies to help them live a productive life.

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Individuals with Jacob&#39;s syndrome are at an increased risk of developing the following conditions<a href="#accordion">[3]</a>:

<ul>
	<li><a href="https://www.merisehat.pk/disease/asthma" target="_blank">Asthma</a></li>
	<li>Seizures&nbsp;</li>
	<li>Tremors</li>
	<li>Abnormalities in the genitourinary system&nbsp;</li>
	<li><a href="https://www.merisehat.pk/disease/infertility-in-men" target="_blank">Infertility&nbsp;</a></li>
	<li><a href="https://www.merisehat.pk/disease/autism" target="_blank">Autism </a>spectrum disorder&nbsp;</li>
	<li>Attention deficit hyperactivity disorder (ADHD)</li>
	<li>Learning disabilities&nbsp;</li>
	<li>Speech difficulties&nbsp;</li>
</ul>

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Male gender is one of the main risk factor in Jacob&#39;s syndrome. However, this condition is not inherited and individuals with Jacob&#39;s syndrome have babies with normal, i.e., 46 chromosome number<a href="#accordion">[6]</a>.

&nbsp;

Since XYY syndrome does not pass on from parents to children, a child born to a father with Jacob&#39;s syndrome will not inherit this disorder. Additionally, this condition is due to a random error during pregnancy; hence, there are no strategies known to prevent this condition<a href="#accordion">[6]</a>.

&nbsp;

A study was carried out on children who were prenatally (before birth) diagnosed with XYY Syndrome and whose parents were counseled regarding their condition. A follow up was done on these patients after multidisciplinary counseling was received by the parents. It included 13 boys aged between 9 months and 7 years.&nbsp;

The results revealed that 9 out of 13 parents were not worried about the future of their child, 2 parents had some concerns about their child, while 2 parents were afraid about their child&#39;s future. Almost all the parents were satisfied with the treatment and did not feel the need to take an opinion from another doctor. Around half of these parents studied about their child&#39;s condition on the internet. Furthermore, 9 of these parents were interested in genetic research that would bring advancement and development in the treatment of children with 47, XYY chromosomes<a href="#accordion">[7]</a>.

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Key Points

<ul>
	<li>XYY syndrome or Jacob&#39;s syndrome is a rare chromosomal disorder affecting males.</li>
	<li>In this disorder, males have 47 chromosomes instead of the usual 46 chromosomes with 2 Y chromosomes.</li>
	<li>It affects 1 in every 1000 males.</li>
	<li>Around 85% of these individuals are not diagnosed due to the absence of specific clinical features.</li>
	<li>Men with XYY syndrome are taller than average, have a large head, and have wide spaced eyes along with other physical features.&nbsp;</li>
	<li>They have normal testosterone levels and do not have fertility issues.</li>
	<li>There may be learning disabilities and speech difficulties.&nbsp;</li>
	<li>Psychological issues, such as <a href="https://www.merisehat.pk/disease/attention-deficit-hyperactivity-disorder-adhd" target="_blank">ADHD </a>and ASD, can be comorbidities.&nbsp;</li>
	<li>Jacob syndrome is diagnosed through blood tests that are able to detect the extra Y chromosome.&nbsp;</li>
	<li>Treatment is based on symptoms.&nbsp;</li>
</ul>

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[1] What Are YY Chromosomes?. WebMD.

[2] XYY Syndrome - NORD (National Organization for Rare Disorders).

[3] Sood B, Clemente Fuentes RW. Jacobs Syndrome. [Updated 2022 Sep 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-.

[4] Conditions G. 47,XYY syndrome: MedlinePlus Genetics.

[5] XYY Syndrome (for Parents) - Nemours KidsHealth.

[6] Cassata C. What Is XYY Syndrome? Symptoms, Causes, Diagnosis, Treatment, and Prevention | EverydayHealth.

[7] Lalatta F, Folliero E, Cavallari U et al. Early manifestations in a cohort of children prenatally diagnosed with 47,XYY. Role of multidisciplinary counseling for parental guidance and prevention of aggressive behavior. Ital J Pediatr. 2012;38(1):52. doi:10.1186/1824-7288-38-52