“…Furthermore, transmission of a deleted chromosome from parent to child appears to be a rare occurrence. Three previous interstitial deletions of the proximal long arm of chromosome 21 are presented in Table 1 with the two patients from this report and with three additional cases that show loss of the proximal long arm of chromosome 21 secondary to a rearrangement, without significant trisomy for another chromosome segment (Rivera et al 1983, Fried et al 1978, Wahrman et al 1976). Other patients with deletion of proximal 21q have been reported , Holbek et al 1974, Al-Awadi et al 1986, Laurent et al 1973, Obry et al 1980; however, these are omitted from the table because they have a significant duplication in addition to the deficiency of 2 1 q.…”