Tuesday, December 13, 2016

A Rare Genetic Deletion

Hello all, some of you know my younger sister has a rare genetic deletion. Today I will be explaining exactly what that is. She actually has an even more specific form of this, however here is a general explanation.

2q37 Deletion Syndrome is a rare genetic deletion. Those who have this deletion have lost genetic material in one of the two chromosome 2s. Since chromosome can break anywhere, the effects of this deletion can vary widely. The deletion is also called, the Albright Hereditary Osteodystrophy-like Syndrome and Brachydactyly-mental retardation syndrome. The deletion is extremely rare and seems to be more common in girls. While the syndrome can be inherited from parents, most cases are not hereditary. However individuals with a deletion carry a 50% chance of passing it on to their offspring. What are the characteristics and challenges of those with 2q37 deletion syndrome?

It is interesting to see the common traits and challenges in babies and children. Babies have low muscle tone which leads to a variety of challenges including feeding difficulties, which is often how the deletion is discovered. Babies are also prone to more general health concerns than are those without the Deletion. Children with a 2q37 Deletion will experience developmental delays and continue to have low muscle tone and loose joints. There are characteristic changes in the facial appearance, hands, and feet of these children. Namely weak musculature, weak or extremely flexible hands, narrow nasal passages, learning disabilities, the tendency to gradually put on too much weight, seizures, eczema, asthma, and frequent chest/ear infections are also common.

Feeding is a major concern during infancy and even toddlerhood. As children grow older the difficulties decrease, however the feeding issues for babies can be life threatening if not realized. Low muscle tone affects the baby’s ability to latch on to a breast or a regular bottle to suck. Thus feeding can take long periods of time and special nipples and devices as well as special milks and formulas must be used to ensure the child receives nutrition. In addition, babies with 2q37 deletion will often not cry to be fed, and so parents and doctors must be extra vigilant in making sure that the baby is getting the necessary feeding and gaining weight. It is common for families to have their own scale and keep close track of the weight lost and gained. Additionally, some babies and toddlers as well as children have Gastro-oesophageal reflux (acid reflux). This is when the milk or food from the stomach comes back up the esophagus bringing up stomach acid with it. Some babies may also be late to move to solids. Most of these issues will disappear by childhood however some children will continue to have acid reflux.

Those with a 2q37 will have developmental delays, however the intensity varies drastically. Generally children function around half of their age. They will lack a sense of balance and can fatigue easily. Due to this, running is often hard and when running children often hold out arms to maintain balance. Many have very lax joints. Physical Therapy and Occupational Therapy, such as swimming and horse therapy, are common and very helpful. Fine motor skills usually develop late or slowly over time, and they may never be quite like that of the average person. Thus physical developments do continually progress forward, simply at a slower pace.

Learning delays are also prevalent in those with 2q37 deletions. These delays, like the developmental delays, vary widely. Some people have only mild learning delays. An example from Unique tells of a mildly delayed 3 ½ year old can recognize some letters and is beginning to spell her name. A moderate delay is the most common and children with a moderate delay can generally learn at around half their age. Being moderately delayed means children and adults may need repetition and lots of sensory breaks to learn something, yet they can indeed learn a lot. Specific learning strengths and weaknesses are scattered from person to person. Music is a useful tool in learning. According to Unique, about half of reading age children can read. A child with a severe case may never learn to walk or speak.

Understanding for those with a 2q37 deletion usually comes ahead of the ability to express themselves. Children and adults can communicate in a variety of ways other than words including but not limited to: eye contact, facial expressions, gestures, vocal noises, pushing, patting, pulling, humming, laughing, and crying. Speech and communication is generally delayed however most children do learn to speak. Some children speak as fluently as any child. The average first words are spoken around two to three years old. Many children are fluent speakers by five or six. On the other hand Unique reports a twelve year old who communicates, “mostly by vocal noises and by pulling” (Unique 2q37 deletion syndrome pg. 15). Some families use picture exchange and electronic systems to aid with communication.

What kind of behavior accompanies these physical and mental delays? Those with 2q37 deletion syndrome are generally cheery, humorous, affectionate, sociable, and happy (Unique 2q37 deletion pg.17) . While their disposition in generally cheerful, they sometimes have difficulty being understood by other children. In addition they often lack social boundaries that come naturally to other children and can become obsessive with friendships. The same bad behaviors that all children have from time to time are prevalent in kids with 2q37 deletion syndrome, however they are more intense and sometimes last longer. People with a 2q37 deletion will often develop odd obsessions, which might not make sense to outsiders but are very important to the individual. Furthermore, they will participate in consistently repetitive behaviors, “This was often speech, either repeating heard sounds and phrases again and again or more often asking the same questions (Is the sun going up or down? What are we doing tomorrow? Where are we going?) repeatedly until deliberately stalled. Younger children were more likely to repeat a simple action, like opening and closing doors; turning light switches on and off; taking shoes on and off; banging. A few children appeared to repeat an action for comfort, such as rocking” (Unique 2q37 Deletion pg. 19).

Some of the above listed behaviors are also characteristic of people with autism. Many children and adults with a 2q37 deletion have autistic traits while about 25% actually also have autism (Genetics Home Reference 2q37 Deletion Syndrome pg. 1). The reason for these similarities and often overlap is, “Chromosome 2 has a group of genes called “homeobox” or HOX genes that control growth and development” (Kelly pg. 100). These genes are vital in creating the brain stem and cerebellum. Since this chromosome is disrupted in children with autism as well as children with this syndrome in which part of that chromosome is actually deleted.

A 2q37 deletion syndrome is so rare there are only approximately 100 reported cases worldwide. Because of this, many parents and families feel alone as the deletion is so rare there is not a lot of outside support and many doctors are not ready with available information on the Deletion. While development both physical and mental is delayed, sometimes significantly, individuals usually continue to progress forward throughout their lives. Babies, children, and adults with 2q37 deletion syndrome face simple as well as severe challenges, but their characteristically thin upper lips, narrow eyes, and arched eyebrows usually form into gleeful smiles and cheerful dispositions.

Sources:

“2q37 deletion syndrome.” Unique Understanding Chromosome Disorders, version 1,
2013, pp. 1-32, www.rarechromo.org/html/DisorderGuideConfirm.asp?ch=Chromosome%20%202&fn=2q37%20deletion%20syndrome%20FTNW.pdf&folder=information

“2q37 deletion syndrome.” Genetics Home Reference, April 2009, pp. 1-2. U.S. National Library of Medicine, ghr.nlm.nih.gov/condition/2q37-deletion-syndrome.

Aldred M et al. “Molecular Analysis of 20 Patients with 2q37.3 Monosomy Definition of Minimum Deletion Intervals for Key Phenotypes.” Journal of Medical Genetics, 41.6, June 2004, pp. 433-439. PMC. doi: 10.1136/jmg.2003.017202

Kelly, Evelyn B., “Autism/ Autism Spectrum Disorders.” Encyclopedia of Human Genetics and Disease, vol. 1, ABC-CLIO, LLC, 2013, pp. 100, Gale Virtual Reference Library, go.galegroup.com.lsproxy.austincc.edu/ps/i.do?p=GVRL&sw=w&u=txshracd2487&v=2.1&it=r&id=GALE%7CCX2723700039&asid=88511bf2415faf14f21181453348252c. Accessed 5 Dec, 2016