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15q13.3 Microdeletion Syndrome

Last updated April 29, 2018

Approved by: Maulik P. Purohit MD, MPH

15q13.3 Microdeletion Syndrome is a genetic disorder caused by a deletion of several genes on chromosome 15. When a syndrome is caused by the deletion of several genes, it is also known as a microdeletion syndrome or a contiguous gene deletion syndrome.


What are the other Names for this Condition? (Also known as/Synonyms)

  • Chromosome 15q13.3 Deletion Syndrome
  • Chromosome 15q13.3 Microdeletion Syndrome
  • Microdeletion 15q13.3 Syndrome

What is 15q13.3 Microdeletion Syndrome? (Definition/Background Information)

  • 15q13.3 Microdeletion Syndrome is a genetic disorder caused by a deletion of several genes on chromosome 15. When a syndrome is caused by the deletion of several genes, it is also known as a microdeletion syndrome or a contiguous gene deletion syndrome
  • Individuals with 15q13.3 Microdeletion Syndrome may have very different signs and symptoms from other affected individuals (even within the same family), or no symptoms at all
  • Features of the condition may include mild to moderate intellectual disabilities, learning delays, or normal intelligence; autism spectrum disorders; epilepsy (recurrent seizures); and mental illness (such as schizophrenia or bipolar disorder)
  • Various dysmorphic (abnormally formed) features have been reported, but there are no consistent physical features among individuals who have the condition
  • 15q13.3 Microdeletion Syndrome is caused by a deletion on the long arm of chromosome 15 that spans at least 7 genes and usually includes the CHRNA7 gene. It can be inherited in an autosomal dominant manner with reduced penetrance, or can occur as a new (de novo) deletion
  • Treatment typically focuses on individual signs and symptoms when possible

(Source: 15q13.3 Microdeletion Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Who gets 15q13.3 Microdeletion Syndrome? (Age and Sex Distribution)

  • 15q13.3 Microdeletion Syndrome is a rare congenital disorder. The presentation of symptoms may occur at birth
  • Both males and females may be affected
  • Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for 15q13.3 Microdeletion Syndrome? (Predisposing Factors)

  • A positive family history may be an important risk factor, since 15q13.3 Microdeletion Syndrome can be inherited
  • Currently, no other risk factors have been clearly identified for the syndrome

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of 15q13.3 Microdeletion Syndrome? (Etiology)

  • 15q13.3 Microdeletion Syndrome is caused by a deletion on the long arm of chromosome 15 that spans at least 7 genes and usually includes the CHRNA7 gene
  • The condition can be inherited in an autosomal dominant manner with reduced penetrance, or can occur as a new (de novo) deletion

(Source: 15q13.3 Microdeletion Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Autosomal dominant: Autosomal dominant conditions are traits or disorders that are present when only one copy of the mutation is inherited on a non-sex chromosome. In these types of conditions, the individual has one normal copy and one mutant copy of the gene. The abnormal gene dominates, masking the effects of the correctly function gene. If an individual has an autosomal dominant condition, the chance of passing the abnormal gene on to their offspring is 50%. Children, who do not inherit the abnormal gene, will not develop the condition or pass it on to their offspring.

In autosomal dominant inheritance with reduced or incomplete penetrance, an individual may not develop symptoms even when he/she is carrying a gene mutation or deletion in each cell of his/her body

What are the Signs and Symptoms of 15q13.3 Microdeletion Syndrome?

The signs and symptoms of 15q13.3 Microdeletion Syndrome may include:

Very frequently present symptoms in 80-99% of the cases: Abnormal facial shape

Frequently present symptoms in 30-79% of the cases:

Occasionally present symptoms in 5-29% of the cases:

  • Abnormality of cardiovascular system morphology
  • Attention deficit hyperactivity disorder
  • Bipolar affective disorder
  • Clinodactyly of the 5th finger
  • Downslanted palpebral fissures
  • Epicanthus
  • Frontal bossing
  • Macrocephaly
  • Macrotia
  • Melanocytic nevus
  • Microcephaly
  • Muscular hypotonia
  • Prominent nasal tip
  • Protruding ear
  • Schizophrenia
  • Seizures
  • Short stature
  • Strabismus

In addition to the above, the following signs and symptoms may be present in some affected individuals:

  • Abnormality of the palpebral fissures
  • Abnormality of the pinna
  • Behavioral abnormality
  • Brachydactyly
  • Hypertelorism
  • Intellectual disability, mild
  • Intellectual disability, moderate
  • Intellectual disability, severe
  • Specific learning disability
  • Synophrys

(Source: 15q13.3 Microdeletion Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is 15q13.3 Microdeletion Syndrome Diagnosed?

15q13.3 Microdeletion Syndrome is diagnosed on the basis of the following information:

  • Complete physical examination
  • Thorough medical history evaluation
  • Assessment of signs and symptoms
  • Laboratory tests
  • Imaging studies
  • Biopsy studies, if necessary

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of 15q13.3 Microdeletion Syndrome?

The potential complications of 15q13.3 Microdeletion Syndrome may include:

  • Delay in reaching developmental milestones
  • Low self-esteem due to one’s appearance
  • Behavioral problems
  • Risk of falls and injury due to seizures

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is 15q13.3 Microdeletion Syndrome Treated?

There is no cure for 15q13.3 Microdeletion Syndrome, since it is a genetic condition. The treatment is usually given to manage the signs and symptoms and any complication that develops.

How can 15q13.3 Microdeletion Syndrome be Prevented?

15q13.3 Microdeletion Syndrome may not be preventable, since it is a genetic disorder, which may arise spontaneously or be inherited.

  • Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
  • If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
  • Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders
  • Regular medical screening at periodic intervals with tests and physical examinations are recommended

What is the Prognosis of 15q13.3 Microdeletion Syndrome? (Outcomes/Resolutions)

  • The prognosis of 15q13.3 Microdeletion Syndrome is dependent upon the severity of the signs and symptoms and associated complications, if any
  • Individuals with mild conditions have better prognosis than those with severe symptoms and complications
  • Typically, the prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for 15q13.3 Microdeletion Syndrome:

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/

What are some Useful Resources for Additional Information?


References and Information Sources used for the Article:


Helpful Peer-Reviewed Medical Articles:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: April 29, 2018
Last updated: April 29, 2018