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June 4, 1982


Author Affiliations

Duarte, Calif
From the Division of Cytogenetics and Cytology, City of Hope National Medical Center, Duarte, Calif.; Member, editorial board, The Journal.

JAMA. 1982;247(21):2949-2950. doi:10.1001/jama.1982.03320460049018

Diagnosis of genetic diseases has become more readily available and precise since the 1960s. Reproducible methods for growing cells, even from a blood sample, and preparation of chromosomes permitting easy karyotyping brought cytogenetics within the access of most clinicians.

Development of electrophoretic techniques capable of resolving structural and enzymatic proteins and detecting their variations increased the diagnostic power of genetics from the gross chromosomal level to the single-gene level. Until now, it was the protein coded by the relevant gene that was analyzed, rather than the gene itself. Thus, the molecule of hemoglobin S is identified in sickle cell disease and not the gene. In Tay-Sachs disease, N-acetylhexosaminidases A and B are ascertained, their absence resulting in blocking of the metabolism of sphingolipids. Absence or variation of the protein is interpreted as absence or modification (mutation) of the gene coding for the protein.

Restriction Enzyme Gene Analysis  Now, the possibilities