The 6th Global Rare Chromosome Disorder Awareness Week is underway! The goal of this event is to educate the public about rare chromosome & gene disorders and celebrate the accomplishments of those living with these conditions. Be sure to check out posts related to #SelfieSunday, #MotivatingMonday, #TellingTuesday, #WarriorWednesday, #ThankfulThursday, and #FundayFriday via social media!
There are two basic groups of chromosome changes that cause chromosome disorders: numerical abnormalities and structural abnormalities.1
Numerical abnormalities: When a person is missing a chromosome or has one or more extra chromosomes. For example, tetrasomy X syndrome, also known as XXXX syndrome, is caused when a female has four copies of the X chromosome as opposed to the typical two copies. Those with this diagnosis have mild physical, speech, and learning delays, slow growth, and increased risk of ovarian dysfunction. Less than 50 women with the condition have been described in the medical literature.2
Structural abnormalities: When the structure of a chromosome is altered by deletions, duplications, translocations, inversions, or rings. For example, 15q11.2 BP1-BP2 deletion syndrome is caused when a piece of chromosome 15 is missing (deleted). Individuals with the deletion may have motor and speech delay, intellectual disability, learning difficulties, ADHD, and/or autism among other features. As of 2017, there were at least 200 individuals known to have 15q11.2 BP1-BP2 deletion syndrome, though the actual number of individuals with this condition is likely much higher.3 Check out our #TellingTuesday post on social media to learn more!
Single gene disorders
Small chromosome changes that affect only a single gene are known as single gene disorders. 1 For example, if a genetic change causes the GRIN2B gene to not work properly, an individual will have GRIN2B-related syndrome. Individuals with this condition may have developmental delay, intellectual disability, low muscle tones, epilepsy, and behavioral problems. Fewer than 100 affected individuals have been reported in the literature.4 Check out Nathan’s family story to learn more!
Diagnosis and Prognosis
Early diagnosis with genetic testing is beneficial for individuals affected with these rare disorders. A genetic diagnosis may provide information about prognosis, medical management, and other underlying health risks. Because many of these conditions are considered rare, the long-term effects of the disorder may be hard to predict. In addition, there are many factors besides a person's chromosome disorder that affect how they develop, such as the person’s unique mixture of genes and the environmental influences within which they are raised. Therefore, is important to remember that every child is unique and will grow and develop at his or her own pace.
Currently, there are no “cures” for the vast majority of chromosome or single gene disorders. Many treatments may be available, however. The Orphan Drug Act (ODA), which was enacted in 1983, encourages more development of medications for rare disorders. ODA is now in its 36th year! Prior to its enactment, only 34 therapies for rare disorders existed. Now there are over 770 therapies on the market! However, there is still work to be done as ~95% of rare disorders are still without an FDA-approved treatment.5Support and Education
Unique, the National Organization for Rare Disorders (NORD), and Chromosome Disorder Outreach Inc. are wonderful organizations dedicated to educating, supporting, and progressing the field of rare chromosome and single gene disorders.
Join us on Friday, June 21 by wearing stripes to symbolize chromosomes banding together!
National Human Genome Research Institute: https://www.genome.gov/about-genomics