Eur J Pediatr (2008) 167:655–659 DOI 10.1007/s00431-007-0568-y
ORIGINAL PAPER
An unexpected finding in a child with neurological problems: mosaic ring chromosome 18 Altuğ Koç & Derya Kan & Kadri Karaer & Mehmet A. Ergün & Meral Yirmibeş Karaoğuz & Kıvılcım Gücüyener & Sophie Hinreiner & Thomas Liehr & E. Ferda Perçin
Received: 25 March 2007 / Revised: 27 June 2007 / Accepted: 28 June 2007 / Published online: 1 August 2007 # Springer-Verlag 2007
Abstract Major neurological disorders may accompany rare chromosomal abnormalities. As an example of this rare condition, we present a case with microcephaly, mental retardation, developmental delay, hyperactivity, stereotypic movements, seizures and dysmorphic facial appearance in whom a mosaic ring chromosome 18 was found [45,XX,18/46,XX,r(18)/46,XX,dicr(18)]. Although ring chromosome 18 phenotype has been known for a long time, this is the third reported patient with a dicentric ring chromosome 18 mosaicism. The presented case will contribute to the identification of the genotype-phenotype correlation in chromosome 18 anomalies. Keywords Ring chromosome 18 . Mosaicism . 18q deletion syndrome . 18p deletion syndrome . Microcephaly . Mental retardation . Trisomy 18
A. Koç : D. Kan : K. Karaer : M. A. Ergün : M. Y. Karaoğuz : E. F. Perçin (*) Department of Medical Genetics, Faculty of Medicine, Gazi University, Ankara, Turkey e-mail:
[email protected] K. Gücüyener Division of Neurology, Department of Paediatrics, Faculty of Medicine, Gazi University, Ankara, Turkey S. Hinreiner : T. Liehr Universitätsklinikum Jena, Institut für Humangenetik und Anthropologie, Jena, Germany
Introduction About 70 cases with ring chromosome 18 [r(18)] have been reported to date [1, 4–6, 8, 9, 11, 15, 16, 19, 20, 22]. Due to the formation process of the ring chromosome 18, which involves the breakage and reunion of the ends of the short and long arms of the chromosome, the phenotypic features of the r(18) patients are similar to the features of the 18q deletion syndrome, whereas a minority of them appear to be like the 18p deletion syndrome or a combination of these two syndromes [17]. The inherent instability of ring chromosomes may cause loss of the ring, double-sized rings or multiple copies of the ring [1, 18, 20], and doublesized (dicentric) rings derived from chromosome 18 have been reported in two cases [12, 13]. Phenotypes of patients with r(18) are usually characterized by microcephaly, mental retardation, short stature, obesity, micropenis, cryptorchidism, hypertelorism, epicanthic folds, micrognathia and small hands [12]. We report on a 6 1/2-year-old Turkish girl with 45,XX,18/46,XX,r(18)/46,XX,dicr(18) karyotype who has microcephaly, mental retardation, developmental delay, hyperactivity, stereotypic movements, and seizures.
Case report The patient was a 6 1/2-year-old girl referred to our clinic because of major neurologic findings: microcephaly, mental retardation, developmental delay, hyperactivity, stereotypic movements, and seizures. Her family and prenatal history were unremarkable. She was born at term, her height was 50 cm (50th centile), her weight was 3,100 g (25–50th centile), and her head circumference was 33 cm (25–50th centile). She sat at 12 months without support, walked at
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Eur J Pediatr (2008) 167:655–659
Fig. 1 Frontal view of the patient at the age of 6.5 years: microcephaly, micrognathia, hypertelorism, lateral hypoplasia of eyebrows, short nose with wide bridge, bulbous nasal tip, and small dysplastic ears
24 months, and spoke her first words by 1 year, but her verbal communication was limited to three words until 5 years. Her IQ score was 65 (WISC-R). On physical examination, her weight was 18.5 kg (10– 25th centile), her height was 107 cm (3–10th centile), and her head circumference was 47 cm (
