[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Conditions](https://durgical.com/en/conditions/) › 16p11.2 deletion syndrome

# 16p11.2 deletion syndrome

A small recurrent loss of chromosome 16 that raises the chance of speech delay, autism, obesity and a large head, with very variable effects.

Updated Nov 13, 2026

On this page

- The basics What it is
- Who gets it
- Causes
- Risk factors
- Pathophysiology
- Classification

- Clinical Symptoms and signs
- Red flags
- Diagnosis
- Complications
- Prognosis

- Treatment Treatment

- Study Test yourself

- Connections Connections

## What it is

A recurrent deletion of about 600 000 base pairs on the short arm of chromosome 16 (band p11.2), removing around 25 genes; it is one of the most common genomic causes of autism and developmental delay.

See it in 3D

- [Frontal lobe](https://durgical.com/en/anatomy/superior-frontal-gyrus/)
- [Hypothalamus](https://durgical.com/en/anatomy/hypothalamus/)
- [White matter](https://durgical.com/en/anatomy/white-matter-of-telencephalon/)

## Who gets it

About 3 in 10 000 people; found in roughly 1 in 100 people with autism spectrum disorder.

## Causes

- Deletion arising from unequal recombination between flanking repeated segments (nonallelic homologous recombination)
- Often de novo; also inherited from a mildly affected or unaffected parent (autosomal dominant with reduced penetrance)

## Risk factors

- A parent carrying the same deletion

## Pathophysiology

Repeated DNA segments on either side of the region misalign at meiosis, and recombination between them deletes the segment between. Losing one copy of several dosage-sensitive genes there affects brain development and energy balance; the duplication of the same segment has roughly mirror-image effects (small head, low weight).

## Classification

- Deletion (this condition)
- Reciprocal 16p11.2 duplication: microcephaly, low weight, developmental and psychiatric risks

## Symptoms and signs

- Delayed speech and language, more than motor delay
- Learning difficulty or intellectual disability (often mild)
- Autism spectrum disorder or attention problems
- Obesity starting in childhood, with increased appetite
- Large head size
- Seizures in some

## Red flags

- Seizures
- Rapid weight gain in childhood

## Diagnosis

**Clinical**
Suspected in a child with speech delay, autism or unexplained developmental delay, often with early obesity or macrocephaly.

**Tests**
Chromosomal microarray detects the deletion; testing both parents clarifies whether it is inherited and the recurrence risk.

**Imaging**
Brain MRI is usually normal or shows minor changes.

## Treatment

**Rehabilitation**
Early speech, occupational and educational support.

**Lifestyle**
Early attention to diet and activity to prevent obesity.

**Medical**
Treatment of seizures and of associated behavioural or psychiatric conditions.

**Follow-up**
Follow-up of growth, weight and development.

## Complications

- Obesity and its metabolic consequences
- Epilepsy

## Prognosis

Very variable: some carriers have no obvious problems, others have significant developmental or behavioural difficulties.

## Test yourself

Think of the answer, then tap the question to see it.

## Which test detects the 16p11.2 deletion?

Chromosomal microarray; a karyotype is too coarse to see it.

## Why can a parent carry the same deletion and be almost unaffected?

The deletion has incomplete penetrance and variable expressivity.

## What do the deletion and the reciprocal duplication of 16p11.2 tend to do to head size and weight?

The deletion tends to cause a large head and obesity; the duplication a small head and low weight.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/conditions/16p11-2-deletion-syndrome/)

## Connections

## Related conditions 1

- [Prader–Willi and Angelman syndromes (imprinting)](https://durgical.com/en/conditions/prader-willi-and-angelman-syndromes/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [16p11.2 deletion syndrome: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/16p112-deletion-syndrome/) (MedlinePlus, US National Library of Medicine, 2026).

[← All conditions](https://durgical.com/en/conditions/)

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

---
Source: https://durgical.com/en/conditions/16p11-2-deletion-syndrome/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/16p11-2-deletion-syndrome/