Tetrasomy 18p is a condition in which a patient has an additional isochromosome consisting of two copies of 18p. Virtually all patients with this condition demonstrate developmental delay, subtle dysmorphism and an abnormal muscle tone (especially spasticity). Many patients also have heart defects, abnormalities of the gastrointestinal tract or genital system but these manifestations are not obligatory. An association of developmental delay and spasticity may resemble cerebral palsy. The Korean girl described in this article who had microcephaly and some dysmorphic features did not have a cytogenetic examination until 9 months of age. The results of her electroencephalography (EEG) and brain MRI were not fully consistent with a proposed diagnosis of cerebral palsy. An examination of her karyotype showed an additional isochromosome 18p. In the United States’ patient the final diagnosis was done at the age of 42 because his EEG indicated potential structural abnormalities. An MRI in this patient showed diffuse cerebral volume loss which was basically consistent with his primary diagnosis of cerebral palsy. This man also had scoliosis and kyphosis. A cytogenetic examination revealed an additional isochromosome 18p. An association of a clinical picture of cerebral palsy with unusual manifestations such as microcephaly, skeletal defects or specific changes on brain MRI or EEG should be suspicious for some specific syndromes including the additional isochromosome 18p.
Mehkri Y. et al. “Tetrasomy 18p initially misdiagnosed as cerebral palsy in an adult patient”. “Cureus” 2021, v. 13, e20053.
Lim I. et al. “Pediatric tetrasomy 18p presenting as a spastic cerebral palsy: a case report”. “J. Genet. Med.” 2021, v. 18, 105-109.
Chromosome Disorder Outreach Inc. medical geneticist and medical advisor Dr. Iosif Lurie M.D. Ph.D examines newly published research studies to locate the most important and relevant for our members. Synopses of these articles are then posted to our website’s research pages. For more information on any article please contact firstname.lastname@example.org