Jacob's syndrome

Info by:Jorge Herrera

What is Jacob's syndrome

Jacobs syndrome is a chromosomal genetic disorder when a male has an extra Y chromosome. Instead of normal XY for male, it becomes XYY. Jacob's syndrome occurs when a male inherits two Y chromosomes from his father instead of one. This means that Jacobs syndrome, or a subtype of Jacobs syndrome, affects less than 200,000 people in the US population.


It approx affects 1 in 1,000 or .001% of the world's population.It only affects males.

What type of inheritance is responsible for creating Jacobsyndrome?This is a nondisjunction disorder where the male has an extra Y chromosome.

More info

Misfolded proteins are affected by Jacob's syndrome. But in normal functioning of misfolded proteins they provide a common framework that may contribute to the elucidation of the cell pathology and guide intervention and treatment strategies of many genetic and age-dependent diseases.

Another person affected by Jacob's syndrome

Stacy Greenleaf has a son named Connor. She said ,“My son Connor has XYY Syndrome. He was diagnosed at 5 1/2 months right after coming into our home. He had characteristics of a child with Downs Syndrome, when I first saw Connor that was what I was sure he had."


Symptoms include:

1)Immaturity- acting in a childish way : having or showing a lack of emotional maturity

2)Learning difficulties- difficulty with learning or schooling.

3)Arthritis-painful inflammation and stiffness of the joints.

4)Camptodactyly- a flexion deformity of the finger where the finger is bent and unable to straighten.

5)Swollen joints-the buildup of fluid in the soft tissue surrounding the joint.It can cause pain or stiffness

6)Joint stiffness- Pain and discomfort in a joint, causing difficulty in movement. Can result frommedical conditions such as arthritis or from injury, especially when there is protective spasm of thesurrounding muscles.

7)Impaired joint mobility-Impaired joint mobility refers to a weakened or inability to move the joints through a full range of motion.

8)Inflamed pericardium- the membrane around the heart is inflamed

9)Chest pain- discomfort or pain that you feel anywhere along the front of your body between your neck and upper abdomen.







The XYY Syndrome cannot be cured, but treatments can help reduce symptoms and the effects caused by it, especially if it is discovered and diagnosed early. Patients can work with health care providers to address any symptoms they may have, such as speech disabilities, hormonal imbalances, and learning problems. As a man gets older, he may want to work with a reproductive specialist to address any infertility concerns.

The following treatment options may be used to address some of the most common effects of XYY Syndrome:


  • Testosterone replacement therapy. Males who do not produce adequate testosterone may need hormone replacement therapy as they grow older. Hormone therapy can help teenage boys undergo normal puberty. It can also help older men improve their sexual drive and energy levels, or increase bone strength and improve muscle mass. This therapy is typically given as an injection, but some patients may be able to use a rub-on gel.
  • Fertility treatment. Men with XYY Syndrome may have low sperm counts and difficulty conceiving a child. Testosterone replacement therapy will not increase fertility, but it can help increase sexual drive. Men wishing to have a child may need to see a fertility specialist to discuss options, such as intracytoplasmic sperm injections (ICSI). During this procedure, sperm is removed from a man’s testicle and then injected directly into a woman’s egg before it is planted back inside of her.


Gynecomastia. Men with excess breast tissue as a result of XYY Syndrome may want plastic surgery to remove the breast tissue.

Alternative Therapies

  1. Speech therapy. Patients with XYY Syndrome may experience speech or motor skill disabilities as a result of the condition. Healthcare professionals can help treat these and provide plans for future improvements.
  2. Physical or occupational therapy. Some younger patients with XYY Syndrome experience delayed motor skill development or difficulty with muscle strength. Physical therapists and occupational therapists can help patients overcome these limitations.
  3. Educational therapy. Some patients with XYY Syndrome experience learning disabilities. Talk with your child’s teacher, principal, and special education coordinators to arrange a schedule that is best suited to your child’s needs. Outside tutors and educational instruction may be necessary.

How is it diagnosed?

How Is XYY Syndrome Diagnosed?

XYY Syndrome may remain undiscovered and undiagnosed until a male reaches adulthood. That’s when fertility problems, such decreased sperm counts, alert doctors to a possible undiagnosed condition.

Two tests may be used to diagnose XYY Syndrome:

  • Hormone testing. Your doctor may request a Sex Hormone-Binding Globulin (SHBG) test to check your testosterone levels. They may request a total testosterone test, too. Both tests analyze blood or urine samples to determine if a man’s testosterone levels are low, a possible indication that he has a problem. If the testosterone levels are low, your doctor may request additional tests to determine the cause.
  • Chromosome analysis. Genetic disorders, such as XYY Syndrome, can be diagnosed with a chromosome analysis. If your doctor is unable to find an explanation for symptoms that may indicate XYY Syndrome, you may be requested to undergo a chromosome analysis to check for XYY Syndrome.