Letter to the Editor
Autism and ring chromosome 18 mosaicism To the Editor: Rocchi et al. (1984) reported in this journal on a slightly mentally retarded female (IQ 73 WISC) with 46,XX/46,XX7r(18)/45,XX,-18 mosaicism in lymphocytes and fibroblasts associated with relative microcephaly, flat occiput and discrete facial dysmorphism. The breakpoints in the ring chromosome 18 were interpreted as being at bands 18pl1.2 and 18q22, respectively. During recent years we have had the occasion to examine two other patients with ring chromosome 18 mosaicism. The first is a 2-year-old7 phenotypically normal boy with normal growth and weight parameters. He presented extreme autistic behaviour which became progressively evident after the age of 1 year. Evaluation at the present age showed a moderate to severe developmental retardation according to the PPAC (Primary Progress Assessment Chart of Social Development) and the BOS 2 (Bayley Developmental Scales 2-IQ 30). He was the third child of healthy, young parents with a negative family history. Chromosomal analysis on two different lymphocyte cultures revealed a 46,XY /46,XY,r( 18) (50%/50%) mosaicism. The ring chromosome 18 was small with breakpoints near the centromere at bands 18pl1.2 and 18q21. The second patient is a 37-year-old female, resident in an institute for the severely mentally retarded. She was severely autistic with almost no social contacts from an early age. Except for short
stature (148 cm) and brachycephaly, no other dysmorphic symptoms were present. Also in this patient, a 46,XX/46,XX,r (18) (75%/25%) mosaicism was found in two peripheral blood lymphocyte cultures and a fibroblast culture of a skin biopsy of the left forearm. The ring chromosome 18 was equally very small with identical breakpoints at 18~11.2and 18q21 bands. The present two patients have many characteristics in common: mosaicism for a very small ring chromosome 18 (breakpoints 18pl1.2 and 18q21), severe autistic behaviour and an almost normal phenotype. These observations add ring chromosome 18 mosaicism to the growing list of genetic conditions causing a severe, primary developmental problem with autism as a cardinal symptom. Jean-Pierre Fryns Alice Kleczkowska
Raference Rocchi M, Cigni I, Archidiacono N, Pecile V, Porcelli G, Filippi G. A young girl with ring (1 8) mosaicism: cytogenetic studies and PEP A mapping. Clin Genet 1984: 2 6 156-160. Correspondence: Centre for Human Genetics Herestraat 49 B-3000 Leuven Belgium
55
Autism and ring chromosome 18 mosaicism To the Editor: Rocchi et al. (1984) reported in this journal on a slightly mentally retarded female (IQ 73 WISC) with 46,XX/46,XX7r(18)/45,XX,-18 mosaicism in lymphocytes and fibroblasts associated with relative microcephaly, flat occiput and discrete facial dysmorphism. The breakpoints in the ring chromosome 18 were interpreted as being at bands 18pl1.2 and 18q22, respectively. During recent years we have had the occasion to examine two other patients with ring chromosome 18 mosaicism. The first is a 2-year-old7 phenotypically normal boy with normal growth and weight parameters. He presented extreme autistic behaviour which became progressively evident after the age of 1 year. Evaluation at the present age showed a moderate to severe developmental retardation according to the PPAC (Primary Progress Assessment Chart of Social Development) and the BOS 2 (Bayley Developmental Scales 2-IQ 30). He was the third child of healthy, young parents with a negative family history. Chromosomal analysis on two different lymphocyte cultures revealed a 46,XY /46,XY,r( 18) (50%/50%) mosaicism. The ring chromosome 18 was small with breakpoints near the centromere at bands 18pl1.2 and 18q21. The second patient is a 37-year-old female, resident in an institute for the severely mentally retarded. She was severely autistic with almost no social contacts from an early age. Except for short
stature (148 cm) and brachycephaly, no other dysmorphic symptoms were present. Also in this patient, a 46,XX/46,XX,r (18) (75%/25%) mosaicism was found in two peripheral blood lymphocyte cultures and a fibroblast culture of a skin biopsy of the left forearm. The ring chromosome 18 was equally very small with identical breakpoints at 18~11.2and 18q21 bands. The present two patients have many characteristics in common: mosaicism for a very small ring chromosome 18 (breakpoints 18pl1.2 and 18q21), severe autistic behaviour and an almost normal phenotype. These observations add ring chromosome 18 mosaicism to the growing list of genetic conditions causing a severe, primary developmental problem with autism as a cardinal symptom. Jean-Pierre Fryns Alice Kleczkowska
Raference Rocchi M, Cigni I, Archidiacono N, Pecile V, Porcelli G, Filippi G. A young girl with ring (1 8) mosaicism: cytogenetic studies and PEP A mapping. Clin Genet 1984: 2 6 156-160. Correspondence: Centre for Human Genetics Herestraat 49 B-3000 Leuven Belgium
55
