A NEW DELETION OF 18Q23 WITH FEW TYPICAL FEATURES OF THE 18Q- SYNDROME

We report on a patient with a deletion of 18q23. At both 2 and 4 years of age, she displayed few of the facial features or other clinical fe atures associated with the 18q- syndrome. Fluorescent in situ hybridis ation and microsatellite marker and RFLP analysis were performed to ch aracterise the extent of the deletion, and a terminal deletion of 18q2 3 was confirmed. The deleted region includes the gene for myelin basic protein, suggesting that hemizygosity of this gene does not invariabl y lead to mental and developmental delay. The clinical presentation of this patient suggests that either she is not deleted for the genes in volved in the 18q- clinical phenotype or this patient represents one e nd of the spectrum of the clinical variability seen with 18q terminal deletions.