2q37 deletion syndrome

Alternate names

Chromosome 2q37 deletion syndrome; Albright hereditary osteodystrophy-like syndrome; Brachydactyly-Intellectual disability syndrome

Definition

2q37 deletion syndrome is a chromosome disease that can affect many parts of the body.2q37 deletion syndrome is caused by a deletion of genetic material from a specific region in the long (q) arm of chromosome 2.

Epidemiology

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

Cause

• 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

• 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.

Signs and symptoms

• Most babies with 2q37 deletion syndrome are born with low muscle tone (hypotonia), which usually improves with age.
• About 25% of those with this syndrome have autism, a developmental condition that affects communication and social interaction.
• The characteristic facial features include a prominent forehead, highly arched eyebrows, deep-set eyes, a flat nasal bridge, a thin upper lip, and minor ear abnormalities.

Other features can include:

• Short stature
• Obesity
• Scoliosis
• Tracheomalacia
• Unusually short fingers and toes (brachymetaphalangy), especially of the fingers 3-5
• Sparse hair
• Heart defects
• Seizures
• A skin disorder called eczema
• A few people with 2q37 deletion syndrome have a rare form of kidney cancer called Wilms tumor.
• Some individuals with 2q37 deletion syndrome can also have malformations of the brain, gastrointestinal system, kidneys, and/or genitalia.

Diagnosis

• Chromosome analysis confirms the diagnosis of 2q37 deletion syndrome in 80%-85% of affected individuals..

* In about 15%-20% of cases the small size of the deleted region can only be detected using deletion analysis (which relies on a variety of methods). 

• In some individuals, 2q37 microdeletion syndrome results from chromosome rearrangements involving 2q37 (e.g., chromosome 2 inversion, ring chromosome 2, or translocation between chromosome 2 and another chromosome).
• Mutation of HDAC4 has been proposed as causative for most of the features of the 2q37 microdeletion syndrome.
• Several affected individuals without microdeletions had inactivating mutation of HDAC4, a gene in the 2q37 deleted region, leading to the proposal that mutation of this gene may be causative for most of the features of the 2q37 microdeletion syndrome.

Treatment

• Multidisciplinary care by specialists in the following fields is often required: clinical genetics, speech pathology, occupational and physical therapy, child development, neurology, cardiology, gastroenterology, nutrition/feeding, ophthalmology, and audiology.
• Infants benefit from enrollment in an early-intervention program; most school-age children benefit from an individualized educational program (IEP)..

NIH genetic and rare disease info

• NIH info on 2q37 deletion syndrome

2q37 deletion syndrome is a rare disease.

2q37 deletion syndrome Resources
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