Gene deletion and duplication effects on phenotype and gamma globulin levels.

In 1964, de Grouchy described the clinical picture associated with partial monosomy for No. 18 chromosome due to a deletion of part of the long arms (de Grouchy et al., 1964a, b).Subsequent case reports have confirmed a phenotypic similarity in individuals with this deletion.Edwards and associates (1960) described a new autosomal trisomy, that of chromosome 18.Since their report, there have been many similar cases described.However, there have also been several cases reported of partial trisomy for No. 18 chromo- some due to translocation of part of this chromosome on to another autosome.We are reporting a family in which there is both a monosomic and a trisomic condition for a portion of the long arms of No. 18 chromosome transmitted through three generations by balanced carriers.Climncal Findings Case III.1 (date of birth 30 April 1968).The pro- band of this family (Fig. 1) is a male infant who was admitted to Rhode Island Hospital at 2 months of age for investigation of failure to thrive.He was the product of a full-term pregnancy of a Gravida 1 Para 0 unmarried female who had taken two types of unknown abortifacients during the 6th to 9th week of gestation.Paternal identity was withheld.The infant was born by spontaneous breech delivery, weighing 3570 g. with a good Apgar rating at 5 minutes.On examination he was found to be a pale, scrawny, irritable infant with mild dehydration and poor sub- cutaneous fat.His weight was 3884 g., height 58 cm., and head circumference 38-5 cm.His head was scaphycephalic; he had a flattened nasal bridge with small nose, epicanthic folds, brushfield spots, thin lips with downtumed corners of the mouth, and a high arched palate.The ears were low set, soft, small, and flat, with minimal hypertrophy of the antitragus and absence of the bifurcation of the antihelix.There was mild retraction of the mid-face.His neck was short;