Molecular biological diagnosis of congenital and acquired cholesteatoma onthe basis of differences in telomere length

Objective: To establish a molecular biological basis for differentiation of congenital and acquired cholesteatoma, Study Design: The time of onset was estimated for congenital cholesteatoma and for acquired cholesteatoma by c omparing the telomere length and the telomerase activity in the tissues of both diseases with the values of those parameters in normal external ear ca nal skin. Methods: The telomere length was determined by extracting DNA fro m each tissue and then applying the Southern blot technique to hybridize it with a P-32-labeled telomeric oligonucleotide (TAAGGG)(8) probe. The telom erase activity was analyzed by a modification of the polymerase chain react ion-based telomeric repeat amplification protocol. Results: The telomere le ngth in congenital cholesteatoma tissue was shorter than the length in norm al external ear canal skin from the same patient, whereas in acquired chole steatoma tissue the telomere length was almost the same as in the normal ex ternal ear canal skin. Some of the acquired cholesteatoma tissue specimens and normal external ear canal skin specimens were positive for telomerase a ctivity, but all of the specimens of congenital cholesteatoma tissue were n egative for telomerase activity. No correlation was found between the prese nce of telomerase activity and the telomere length. Conclusions: The presen t results indicate that congenital cholesteatoma manifests at an earlier ti me compared with acquired cholesteatoma, and the results can be thought to support the theory that congenital cholesteatoma originates from vestigial fetal tissue or aberrant tissue. In addition, the finding that telomerase a ctivity was weak in the congenital cholesteatoma tissue suggests the possib ility that vestigial fetal tissues and aberrant tissues are naturally elimi nated in normal subjects as a result of apoptosis.