犬歯転座患者の第一度近親者における歯列異常

Dental anomalies in first-degree relatives of transposed canine probands.

抄録

本研究の目的は、上顎犬歯第一小臼歯転座患者およびその第一度近親者のサンプルにおける遺伝性歯科異常の遺伝パターンと有病率を、口蓋変位犬歯家族のサンプルと調査・比較することであった。連続した上顎犬歯第一小臼歯転位症患者35人と第一度近親者111人を、連続した口蓋変位犬歯患者35人と第一度近親者115人とマッチングさせた。これらは口蓋犬歯転位と切歯・小臼歯低歯症を評価した．また、口蓋垂歯列矯正者の出生時の親の年齢も記録された。その結果、(i)口蓋変位犬歯および切歯前歯低歯症の全有病率は親族間で差がない、(ii)両側口蓋変位犬歯患者の第一度近親者は、片側口蓋変位犬歯患者より口蓋変位犬歯および切歯前歯低歯症の保有率が高いことが判明した。(iii) 上顎犬歯第一小臼歯転位症患者の母親の出生時年齢は、口蓋犬歯転位症患者のそれよりも有意に高いことがわかった。この結果は、上顎犬歯第一小臼歯転位症と口蓋犬歯転位症が異なる遺伝子の存在である可能性は低く、また、歯の発達に環境またはエピジェネティックな影響を及ぼすことを示唆している。

The aim of this study was to investigate and compare the inheritance pattern and prevalence of inheritable dental anomalies in a sample of patients with maxillary canine-first premolar transposition and their first-degree relatives with a sample of palatally displaced canine families. Thirty-five consecutive maxillary canine-first premolar transposition probands and 111 first-degree relatives were matched to 35 consecutive palatally displaced canine probands and 115 first-degree relatives. These were assessed for palatally displaced canines and incisor-premolar hypodontia. Parental age at birth of the proband was also noted. The results revealed that (i) there is no difference in the overall prevalence of palatally displaced canine or incisor-premolar hypodontia between the groups of relatives; (ii) first-degree relatives of bilateral palatally displaced canine probands have a higher prevalence of palatally displaced canine and incisor-premolar hypodontia than those with unilateral palatally displaced canine; and (iii) maternal age at birth of the maxillary canine-first premolar transposition probands was significantly higher than that of the palatally displaced canine probands. The results suggest that maxillary canine-first premolar transposition and palatally displaced canine are unlikely to be different genetic entities and also indicate environmental or epigenetic influences on dental development.