1p36 Deletion Syndrome (cont.)
Charles Patrick Davis, MD, PhD
Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
William C. Shiel Jr., MD, FACP, FACR
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
In this Article
- 1p36 deletion syndrome facts
- What is and what causes 1p36 deletion syndrome?
- What are the characteristics, signs, and symptoms of 1p36 deletion syndrome?
- What is the treatment for 1p36 deletion syndrome?
- What is the prognosis and life expectancy for 1p36 deletion syndrome?
- Find a local Doctor in your town
What is and what causes 1p36 deletion syndrome?
As humans, we all should share 23 chromosomes from each parent, for a total of 46. But what happens when some of the genetic material (genes made from DNA) in the chromosomes is missing? The outcome depends on the functions that the genetic material control. Unfortunately, in a relatively newly identified problem, 1p36 deletion syndrome, (first deletion noted in 1981 and in 1997, the clinical features first outlined), a small segment of missing DNA results in large problems for individuals missing the DNA and for their families.
The name of the problem is 1p36 deletion syndrome. This numeric name means that it affects chromosome # 1, the largest human chromosome. It precisely affects the area on the #1 chromosome that is on a short arm of the chromosome (p means the short arm above the centromere that joins the two parental copies of chromosome 1, and area 36 is where the missing DNA should be located). In recent years (about 2005-08), recent diagnostic tests known as fluorescent in situ hybridization (FISH) and microarray comparative genomic hybridization (array CGH) have been developed to definitively diagnose the 1p36 deletion syndrome. CGH may determine about how much DNA is missing.
What are the characteristics, signs, and symptoms of 1p36 deletion syndrome?
Unfortunately, for the affected individuals and family, missing DNA in this section is very influential on a person's overall development and is often unnoticed until the newborn or infant is noted to miss physical or developmental landmarks. These landmarks that are missed or severely delayed comprise the symptoms and signs of 1p36 deletion syndrome. Not all symptoms will be present in each individual because there is variation from person to person and, in general, most researchers think that the more DNA missing from 1p36, the more intense or apparent these symptoms will appear.
Many individuals will have a small head size that is short and wide (about 75%); many have noticeable facial features of deep-set eyes with straight-appearing eyebrows, a sunken–appearing face with a broad flat nose and an elongated area from nose to mouth, a pointed chin, low-set ears that are rotated backwards and are abnormally shaped. Some individuals are preliminarily diagnosed from their appearance described above; others may have less noticeable physical symptoms and require FISH or CGH tests for diagnosis.
To confirm or establish the diagnosis it is appropriate to test any individual suspected of having 1p36 deletion syndrome as follows:
- Conventional cytogenetic studies to detect large deletions (i.e., > 5 Mb) and more complex cytogenetic rearrangements (unbalanced chromosome translocations)
- FISH with at least two subtelomeric region-specific probes (Vysis 1p subtel probe, Vysis p58 probe; D1Z2 Oncor probe or CEB108/T7) to detect unbalanced translocations and to identify parental chromosome rearrangements
- Deletion/duplication analysis by CMA to detect smaller deletions (i.e., > 5 Mb) or interstitial deletions or complex rearrangements
There are other problems (symptoms) that many individuals with 1p36 deletion syndrome develop:
- About 90% have severe learning disabilities
- About 75% will have no ability to form words, the other approximate 25% will only develop a few words or phrases
- About 70% develop types of heart problems
- About 50% will develop seizures, behavior problems, and hearing problems
- Other problems such as weak muscle tone, breathing problems, eye problems, swallowing problems, genital malformations (usually minor in males), and metabolic problems have been reported
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