2q37 deletion syndrome

Chromosomes are the structures that hold our DNA. Our DNA contains the instructions, called genes, which tell our bodies how to develop and function. Humans have 23 pairs of chromosomes, so 46 in total. One of each pair is inherited from our mother and the other from our father. Click here to view an illustration of a chromosome and DNA.^[1]

Chromosomes vary in size. Each chromosome has a constriction point, called the point, called the centromere, which divides it into two sections. The shorter arm is called the p arm, and the longer arm is called the q arm.^[1] To read more about chromosomes, click here.

A deletion involves losing part of a chromosome and is sometimes known as a partial monosomy. Deletions can occur in any part of any chromosome, and there can be one or two breaks in the chromosome. When there is just one break in the chromosome, the deletion is called a terminal deletion because the end (or terminus) of the chromosome is missing. When the missing piece is closer towards the end of the chromosome, it is called a distal deletion.^[2]

A deletion on 2q37 means that a segment on the long arm (q arm) of chromosome 2 at position 37 is missing or deleted. This is also called a terminal deletion and/or distal deletion.

2q37 deletion syndrome is a chromosome disease that can affect many parts of the body. About 100 cases have been reported worldwide. This condition is characterized by short stature, weak muscle tone (hypotonia) in infancy, mild to severe intellectual disability and developmental delay, autistic behavior, obesity, characteristic facial features, and other physical abnormalities, such as short bones of the hand and of 3-5 fingers, and abnormal lateral curvature of the spine (scoliosis). Other findings include seizures (20%-35%), congenital heart disease, brain abnormalities (hydrocephalus, dilated ventricles), umbilical/inguinal hernia, tracheomalacia, gastrointestinal abnormalities, and kidney malformations. 2q37 deletion syndrome is caused by a deletion of the genetic material from a specific region in the long (q) arm of chromosome 2. Most cases are not inherited.^[3] Treatment depends on the symptoms and may require several specialists.^[4]

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.^[3] 

Other features can include:^[4][3]

• 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.^[3]

Unique is a source of information and support to families and people with rare chromosome disorders. On their website, they have a pamphlet that provides additional information on the signs and symptoms of 2q37 deletion syndrome.

2q37 deletion syndrome is caused by a deletion of genetic material from a specific region in the long (q) arm of chromosome 2. The deletion occurs near the end of the chromosome (terminal deletion) at a location designated 2q37. The size of the deletion may vary from person to person with 2q37 deletion syndrome. The signs and symptoms of this syndrome are probably related to the loss of multiple genes in this region, especially pertaining to the loss of the HDAC4 gene.^[3] Mutations of the HDAC4 gene result in similar symptoms as the 2q37 deletion syndrome.^[4] 

Most individuals with the 2q37 deletion syndrome have a de novo chromosome deletion and their parents have normal chromosomes. In about 5% of published cases, patients have inherited the deletion from a parent who has a balanced translocation. People with a balanced translocation do not have any losses or gains of genetic material and, in general, don't have symptoms.^[4]

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.^[3]

Rarely, affected individuals inherit a copy of chromosome 2 with a deleted segment from an unaffected parent. In these cases, one of the parents carries a chromosomal rearrangement between chromosome 2 and another chromosome. This rearrangement is called a balanced translocation. No genetic material is gained or lost in a balanced translocation, so these chromosomal changes usually do not cause any health problems. However, translocations can become unbalanced as they are passed to the next generation. Children who inherit an unbalanced translocation can have a chromosomal rearrangement with extra or missing genetic material. Some individuals with 2q37 deletion syndrome inherit an unbalanced translocation that deletes genetic material near the end of the long arm of chromosome 2, which results in birth defects and other health problems characteristic of this disorder.^[3]

To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself. Online directories are provided by the American College of Medical Genetics and the National Society of Genetic Counselors. If you need additional help, contact a GARD Information Specialist. You can also learn more about genetic consultations from Genetics Home Reference.