15q11.2 microdeletion syndrome

What it is

From: Orphanet

15q11.2 microdeletion syndrome is a rare partial autosomal monosomy with a variable phenotypic expression and reduced penetrance associated with an increased susceptibility to neuropsychiatric or neurodevelopmental disorders including delayed psychomotor development, speech delay, autism spectrum disorder, attention deficit-hyperactivity disorder, obsessive-compulsive disorder, epilepsy or seizures. It may also include mild non-specific dysmorphic features (such as dysplastic ears, broad forehead, hypertelorism), cleft palate, neurological and neuroimaging abnormalities (such as ataxia and muscular hypotonia).

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Abnormal facial shape · Frequent (79-30%)

An abnormal morphology (form) of the face or its components.

Abnormal palate morphology · Frequent (79-30%)

Any abnormality of the palate, i.e., of roof of the mouth.

Abnormal pinna morphology · Frequent (79-30%)

An abnormality of the pinna, which is also referred to as the auricle or external ear.

Attention deficit hyperactivity disorder · Frequent (79-30%)

Attention deficit hyperactivity disorder (ADHD) manifests at age 2-3 years or by first grade at the latest. The main symptoms are distractibility, impulsivity, hyperactivity, and often trouble organizing tasks and projects, difficulty going to sleep, and social problems from being aggressive, loud, or impatient.

Atypical behavior · Frequent (79-30%)

Atypical behavior is an abnormality in a person's actions that can be controlled or modulated by the will of the individual. While abnormal behaviors can be difficult to control, they are distinct from other abnormal actions that cannot be affected by the individual's will.

Brain imaging abnormality · Frequent (79-30%)

An anomaly of metabolism or structure of the brain identified by imaging.

Delayed speech and language development · Frequent (79-30%)

A degree of language development that is significantly below the norm for a child of a specified age.

Dyslexia · Frequent (79-30%)

A learning disorder characterized primarily by difficulties in learning to read and spell. Dyslectic children also exhibit a tendency to read words from right to left and to confuse letters such as b and d whose orientation is important for their identification. Children with dyslexia appear to be impaired in phonemic skills (the ability to associate visual symbols with the sounds they represent).

Global developmental delay · Frequent (79-30%)

A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.

Intellectual disability · Frequent (79-30%)

The term intellectual disability or intellectual developmental disorder is used to describe significantly sub-average intellectual and adaptive functioning based on clinical assessment and as measured by individually administered, appropriately normed, standardized and validated tests of intellectual functioning and adaptive behavior, with onset during the developmental period from infancy through adolescence.

Memory impairment · Frequent (79-30%)

An impairment of memory as manifested by a reduced ability to remember things such as dates and names, and increased forgetfulness.

Motor delay · Frequent (79-30%)

A type of Developmental delay characterized by a delay in acquiring motor skills.

Thick cerebral cortex · Frequent (79-30%)

Abnormal heart morphology · Occasional (29-5%)

Any structural anomaly of the heart.

Other findings in the same source

From: Orphanet

Additional reported features include Ataxia (Occasional (29-5%)); Autism (Occasional (29-5%)); Autistic behavior (Occasional (29-5%)); Broad forehead (Occasional (29-5%)); Microcephaly (Occasional (29-5%)); Postural instability (Occasional (29-5%)); Schizophrenia (Occasional (29-5%)); Seizure (Occasional (29-5%)); Self-injurious behavior (Occasional (29-5%)); Short attention span (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: Orphanet

Infancy; Neonatal

Inheritance in the source

From: Orphanet

Not applicable

Frequency and the population described

From: Orphanet

Reported case(s): 200.0; Worldwide. This is a published case count, not prevalence. Point prevalence: <1 / 1 000 000; Worldwide; Class only.

Which doctor should you see?

The suggested department for discussing 15q11.2 microdeletion syndrome is Clinical Genetics, with a clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with clinical geneticist referral.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Does the exact genetic or chromosome finding explain the observed features?
• Would a genetic counsellor help the family understand the result?
• Which organ-specific assessments are appropriate for this particular diagnosis?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for 15q11.2 microdeletion syndrome. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.