Trisomy-18 syndrome caused by translocation or isochromosome formation. A case report with bibliography.

A girl with the clinical and pathological charac- teristics of Edwards' syndrome (Edwards et al, h: 1960) and with a karyotype showing only one morphologically recognizable chromosome 18 is reported.The 2nd and the additional 3rd chromo- some 18 were replaced by 2 metacentric chromo- somes of different size.Possible mechanisms of origin of the abnormal chromosomes are discussed.Case Report Clinical Findings.The proposita (Fig. 1) was the 3rd child of healthy Italian parents having no common ancestors and without any family history of malforma- tions.The mother indicated no previous abortions.The first 2 children are living and clinically well.The karyotypes of the parents were found to be normal.Birth of the proposita occurred spontaneously 2-i weeks before term following an uneventful pregnancy.The father was 31 years of age at that time, the mother 25 years.The placenta was said to be normal by the ob- stetrician, however amniotic fluid contained meconium.The baby became blue asphyxtic and was referred to our hospital.Birth weight was 2380 g, body length 45 cm, and head circumference 31-5 cm.The head had a prominent occiput with widely spaced sutures.There was a flat bridge of the nose.The proposita showed micrognathia, high arched palate, low set malformed ears, small eyes with a slight mongo- loid slant of the palpebral fissures, and peripheral paresis of the left facial nerve.The thorax was barrel shaped with widely spaced FIG. 1.The proposita at the age of 1+ months.