A case of a supernumerary metacentric small chromosome, diagnosed at birth, is described. The cytogenetic findings support its identification as i(18p). The clinical development from birth to 12 months is reported, with particular attention given to the psychomotor retardation and to the immunological aspect.

BACKGROUND Turner syndrome is caused by numeric and structural abnormalities of the X chromosome. An increased frequency of autoimmunity as well as an elevated incidence of autoantibodies was observed in Turner patients. The aim of this study was to conduct a retrospective analysis of the incidence of autoimmunity in 66 Italian patients affected by Turner syndrome. METHODS Sixty-six unselecte...

PURPOSE To determine the extent to which high myopia in a cohort of 51 U.K. families can be attributed to currently identified genetic loci. METHODS The families comprised 245 subjects with phenotypic information and DNA available, of whom 170 were classified as affected. Subjects were genotyped for microsatellite markers spanning approximately 40cM regions on 18p (MYP2), 12q (MYP3) and 17q, ...

A de novo supernumerary marker chromosome (SMC) was identified in a 13-month-old girl who presented with microcephaly and mild mental retardation. On further characterization by oligo-nucleotide array-comparative genomic hybridization [array-CGH], the SMC was confirmed to be 18p.