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ABSTRACT
The clinical and laboratory data of four pediatric patients and one adult patient with inverted duplication (inv dup) (15) are reported. The most evident findings were dysmorphic features with frontal bossing; genital abnormalities, such as macropenis or hypospadias; mental retardation; autistic behavior; and seizures. two additional adults with inv dup (15) from other institutions were also diagnosed in our laboratory. Seizures and mental retardation were the reasons for their referral. The clinical picture of inv dup (15) seems to be quite variable since the phenotype can also be normal. However, karyotyping and fluorescent in-situ hybridization, focused in particular on chromosome 15, appear to be indicated in patients with dysmorphic phenotypes, such as the one present in our patients, and in subjects with early-onset seizures and psychomotor retardation with autistic features. (J Child Neurol 2000;15:380-385).
Chromosomal abnormalities are not infrequently associated with various types of epileptic seizures. Examples are Angelman's syndrome, caused by a lack of maternal imprinting on chromosome 15, in which seizures occur in 90/ of patients,1 and Down syndrome, in which the prevalence of seizures is 17%.(2) Conversely, seizures are rare and the electroencephalogram (EEG) is usually normal in Prader-Willi syndrome.
Extrastructurally abnormal chromosomes, supernumerary marker chromosomes, or marker chromosomes are found in karyotyping for prenatal diagnosis in about 8 of 10,000 examinations.3 The use of fluorescent in-situ hybridization has demonstrated that extrastructurally abnormal chromosomes frequently originate in the pericentromeric region of chromosome 15.(4) In a recent study, Hou and Wang stressed that the phenotypic diversities existing in children with inverted duplication (inv dup) (15) depended on the size or genetic composition of the markers, degree of mosaicism, parental origin, and familial occurrence.5 However, in other studies there was an inconsistent relationship between marker size, gene dosage, and severity of phenotype.6,7 Angelman's and Prader-Willi syndromes have clinical phenotypes that can be clearly indicative for diagnosis. In about 75% of cases, a deletion in the 15q11-13 critical region, which is maternal in Angelman's syndrome and paternal in Prader-Willi syndrome, can be demonstrated. Also in inv dup (15), parent-of-origin studies revealed that inv dup (15) was maternal in origin.7 We describe the clinical picture of inv dup (15) and EEG findings in the condition. They are considered different from those present...