Quinacrine fluorescence and Giemsa banding in trisomy 22
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Using quinacrine fluorescence and Giemsa banding techniques we have identified an extra chromosome 22 in three non-mongoloid children with similar phenotypes and 47 chromosomes. In one of the children, the long arm of the extra 22 was shorter than usual. This 22q—chrcmcscme was observed in 4 normal family members with 46 chromosomes. In a fourth child, with similar physical findings, the extra G chromosome was shown to be neither a normal 21 nor 22. It must have arisen from a rearrangement in a parental gamete since it was not present in either parent's karyotype.
No constellation of clinical findings, in association with an extra G chromosome, is sufficient evidence for the diagnosis of trisomy 22. The positive identification of the extra chromosome must be made using fluorescence and banding.
KeywordsFamily Member Clinical Finding Sufficient Evidence Similar Phenotype Normal Family
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