2q37 deletion syndrome

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

2q37 deletion syndrome is a condition that can affect many parts of the body. Most babies with 2q37 deletion syndrome are born with weak muscle tone (hypotonia), which usually improves with age. Other neurological abnormalities that are common in affected individuals include mild to severe intellectual disability; delayed development of motor skills, such as sitting and walking; and behavioral problems. About 25 percent of people with this condition have autism spectrum disorder, a developmental condition that affects communication and social interaction.

Unusual physical features are also common in people with 2q37 deletion syndrome. About half of affected individuals have unusually short fingers and toes (brachydactyly), often with abnormally short fourth toes that may overlap the other toes. Additional features of this condition may include short stature, obesity, or sparse hair. Many people with 2q37 deletion syndrome have characteristic facial features that can include a prominent forehead, a low frontal hairline, thin eyelids, skin folds covering the inner corner of the eyes (epicanthal folds), outside corners of the eyes that point upward (upslanting palpebral fissures), a small nose, a small mouth with thin lips, a smooth space between the upper lip and nose (smooth philtrum), prominent cheekbones, a large chin, and minor ear abnormalities.

Other features of 2q37 deletion syndrome can include seizures and an inflammatory skin disorder called eczema. Some affected individuals have malformations of the brain, heart, gastrointestinal system, kidneys, or genitalia. A few people with 2q37 deletion syndrome develop a rare form of kidney cancer called Wilms tumor.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

2q37 deletion syndrome is caused by deletions of genetic material from a specific region in the long (q) arm of chromosome 2. The deletions occur near the end of the chromosome at a location designated 2q37. The size of the deletion varies among affected individuals, with most affected people missing 2 million to 9 million DNA building blocks (also written as 2 Mb to 9 Mb).

Researchers are working to identify all of the genes whose loss contributes to the features of 2q37 deletion syndrome. Many of these genes have not been well characterized. However, genes in this region appear to be critical for the normal development of many parts of the body.

Researchers have determined that loss of a particular gene on chromosome 2, called HDAC4, is likely to account for many of the syndrome's characteristic signs (such as intellectual disability and skeletal abnormalities). While the deleted segment in 2q37 deletion syndrome varies in size, it always contains the HDAC4 gene. Additionally, a few people with mutations in only the HDAC4 gene have many of the features of 2q37 deletion syndrome. It is unclear what role the other genes on 2q37 play in this disorder.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

Most cases of 2q37 deletion syndrome are not inherited. They result from a chromosomal deletion that occurs as a random event during the formation of reproductive cells (eggs or sperm) or in early fetal development. Affected people typically have no history of the disorder in their family.

Rarely, an affected individual inherits a copy of chromosome 2 with a deleted segment from an affected parent. In these cases, the parent is usually less severely affected than the child, for reasons that are unknown. When an affected child inherits a chromosomal deletion from a parent, it is inherited in an autosomal dominant pattern, which means one copy of the altered chromosome in each cell is sufficient to cause the disorder.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

2q37 deletion syndrome appears to be a rare condition, although its exact prevalence is unknown. At least 115 cases have been reported worldwide.

Which doctor should you see?

The suggested department for discussing 2q37 deletion 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 2q37 deletion 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.