Neurobehavioral & Cognitive Disorders
Dementia in Parkinson disease
Aug. 16, 2024
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Toll Free (U.S. + Canada): 800-452-2400
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Support: service@medlink.com
Editor: editor@medlink.com
ISSN: 2831-9125
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Chromosomal aneuploidies refer to abnormalities in the total number of chromosomes carried by an individual. The normal number of chromosomes is 46 as established by Joe Hin Tjio in 1956. Because each chromosome carries a large number of genes, the addition or loss of even one chromosome disrupts the normal equilibrium of cells and, in most cases, is incompatible with life.
Broadly speaking, chromosomal abnormalities are associated with dysmorphic features, intellectual delay, seizures, and a shortened life span.
Although there have been isolated case reports and small-scale studies on the presence of movement abnormalities, especially tremor, in people with chromosomal aneuploidies, there is a lack of awareness among clinicians regarding the existence of such disorders. In this article, the authors reviewed data concerning these disorders with the goal of further educating physicians, neurologists, and movement disorder specialists about the extent of abnormal movements in patients with chromosomal aneuploidies. In doing so, the authors hope to increase clinicians’ diagnostic capability and, in turn, help improve the quality of life for these patients with the institution of appropriate management early in the disease course.
• The authors scanned the literature for chromosomal aneuploidies that are compatible with life and then systematically looked for the presence of abnormal movements in these people. | |
• Trisomy 13, 18, and 21 are the only autosomal aneuploidies reported to be compatible with life; trisomy 21 cases are the most common and, hence, most studied. | |
• Patients with trisomy 18 rarely survive beyond childhood, and those with trisomy 13 rarely survive beyond infancy. | |
• Other autosomal aneuploidies exist as mosaicisms, notably mosaic trisomy 15 and the Pallister Killian syndrome, none of which have a reported movement disorder. Overall, mosaic abnormalities with subtle features probably go undiagnosed. | |
• Compared to autosomal aneuploidies, sex chromosomal aneuploidies are more common, with milder phenotypes and longer life spans, many going undiagnosed owing to the lack of classic textbook signs and symptoms as mentioned above. After noting the preponderance of sex chromosomal abnormalities, the authors focused their search on these syndromes. | |
• The sex chromosomal aneuploidies found in the literature are syndromes of supernumerary X and Y chromosomes, with Turner syndrome (monosomy 45X0) being the only complete monosomy compatible with life. The authors did not review chromosomal rearrangement syndromes that resulted from the initial search. | |
• The authors then searched PubMed using combinations of the specific chromosomal abnormality (Down syndrome, Turner syndrome, Klinefelter syndrome, Jacob syndrome, 47 XXX, 48XXYY) with a specific movement disorder (tremor, myoclonus, dystonia, and chorea individually). | |
• A proposed hypothesis for the relative compatibility of sex chromosomal aneuploidies with life could be the physiological inactivation of one X chromosome in females and the relatively few genes carried by the Y chromosome (32). |
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MedLink®, LLC
3525 Del Mar Heights Rd, Ste 304
San Diego, CA 92130-2122
Toll Free (U.S. + Canada): 800-452-2400
US Number: +1-619-640-4660
Support: service@medlink.com
Editor: editor@medlink.com
ISSN: 2831-9125