15q11.2 microdeletion

Alternate names

Chromosome 15q11.2 microdeletion; Chromosome 15q11.2 deletion; Del(15)(q11.2); 15q11.2 microdeletion syndrome; Monosomy 15q11.2; 15q11.2 BP1-BP2 microdeletion syndrome

Definition

15q11.2 microdeletion refers to a chromosome abnormality in which a tiny piece of genetic material on the long arm of chromosome 15 (at a location designated q11.2) is missing (deleted).

Cause

• A 15q11.2 microdeletion may occur randomly for the first time in an affected person (a de novo mutation), or it may be inherited from a parent with the microdeletion.
• A blood test to look at the parents' chromosomes is needed to find out how the microdeletion occurred.
• When a 15q11.2 microdeletion occurs as a de novo mutation, it is due to a random error - either during the formation of a parent's egg or sperm cell, or very soon after conception (fertilization of the egg).
• A parent with the microdeletion has a 50% chance with each pregnancy to pass on the microdeletion.
• The features of 15q11.2 microdeletion occur because the deleted region of the chromosome contains several genes that are important for normal growth and development.
• It is not yet clear why there is a large range of features and severity among people with a 15q11.2 microdeletion, or why some people are unaffected.

Inheritance

A 15q11.2 microdeletion may occur randomly for the first time in an affected person, or it may be inherited from a parent.

Signs and symptoms

The signs and symptoms in people with a 15q11.2 microdeletion can vary widely. Some people with the microdeletion don't have any apparent features, while others are more severely affected. When not all people with a genetic abnormality are affected, the condition is said to have reduced penetrance. When signs and symptoms vary among affected people, the condition is said to have variable expressivity.

The most commonly reported features in people with a 15q11.2 microdeletion include:

• Neurological dysfunction
• Developmental delay
• Language delay
• Motor delay
• ADD/ADHD
• Autism spectrum disorder.

Other signs and symptoms that have been reported include seizures; abnormally shaped ears; abnormalities of the palate (roof of the mouth); memory problems; behavioral problems; and mental illness. While some babies with a 15q11.2 microdeletion are born with a minor or serious birth defect, many babies are born completely healthy.

Treatment

Treatment depends on the signs and symptoms in each person.

NIH genetic and rare disease info

• NIH info on 15q11.2 microdeletion

15q11.2 microdeletion is a rare disease.