Age-related mitochondrial DNA mutations in the human larynx

Objective: To determine whether age-related mitochondrial DNA mutations occ ur in the human larynx. Study Design: Genetic study of cadaveric larynx spe cimens. Methods: Vocal fold mucosa, thyroarytenoid muscle, and cricoaryteno id joint tissue were harvested from 13 fresh postmortem larynges (age range , 2 d-82 y), DNA was extracted from each sample, and the polymerase chain r eaction (PCR) was used to amplify a target DNA sequence resulting from the common age-associated, 4977-base-pair (bp) mitochondrial DNA deletion. PCR products were visualized by agarose gel electrophoresis, Automated sequenci ng determined the sequence of identified PCR products. Subjects: Thirteen c adaveric larynges were obtained through the University of Kentucky Medical Center (Lexington, KY). Specimens from patients with a history of head and neck cancer, previous laryngeal trauma, or surgery were excluded. Results: Strongly positive bands were identified in samples from three individuals. Weaker bands were seen in samples from four other samples. No band was note d from the two pediatric larynges, Different band patterns were seen among the three different tissue sites in the larynges with positive PCR products , but no consistent pattern was seen. Sequencing of the identified PCR prod ucts from selected samples confirmed that they were products of the age-ass ociated, 4977-bp mitochondrial DNA deletion. Conclusions: An age-associated mitochondrial DNA deletion was detected in several postmortem human laryng es, Its presence seemed to increase in appearance with age. In the larynges in which the deletion occurred, there were individual regional differences in the occurrence of the deletion, but no consistent pattern was noted acr oss all individuals who carried the deletion.