Identification of chromosomal region(s) influencing tooth root development in mouse

在人类中，下颌第二磨牙或第三磨牙的融合根被称为沟形根（GSR）。许多研究者报道了这种异常的形态特征，但其原因尚不清楚。据报道，C57 L/J小鼠是研究其原因的最有用的模型之一;已知GSR的发生率约为90- 100%。对C57 L/J小鼠GSR病因的经典遗传学研究表明，一种常染色体显性遗传的遗传因素影响小鼠GSR的发生，且涉及多个基因。最近，我们证明了micro-CT是一个非常有用的工具，以量化小鼠GSR作为一个数量性状。本研究的目的是确定C57 L/J小鼠中主要的候选染色体，并检测可能包括导致GSR的候选基因的区域。N2回交[（C57 L × AKR）F1 × AKR]小鼠是在本实验室通过交配获得的。利用MapManager QTXB 11进行QTL分析中的区间作图。选择6、7和8号染色体作为携带导致小鼠牙根异常的基因的候选者。在第6染色体上的D 6 Mit 230处发现了高显着连锁，在第8染色体上的D 7 Mit 105和D8 Mit 65附近发现了其他显着连锁。这些结果表明，负责小鼠根形成的主要基因位于这些区域。

In human, the fused root of the second molar or third molar in the lower jaw is known as gutter-shaped root (GSR). Many investigators have reported the morphological features of this anomaly, but its cause is not known. It has been reported that C57L/J mice are one of the most useful models for studying its cause ; the incidence rate of GSR is known to be about 90-100%. A classic genetic study on the cause of GSR in C57L/J mice was reported to suggest that a genetic factor with autosomal-dominant inheritance affected the development of mouse GSR, and that a few genes were involved. Recently, we demonstrated that micro-CT is a very useful tool to quantify mouse GSR as a quantitative trait. The purpose of this study was to identify the major candidate chromosome and to detect the region that would include the candidate gene causing GSR in the C57L/J mice. N2 backcross [(C57L X AKR)F1 X AKR] mice were obtained by mating the mice in our laboratory. Interval mapping that was one of the QTL analysis was performed with the used of MapManager QTXb11. Chromosome(s) 6, 7 and 8 were selected as candidate bearing the gene causing the tooth root anomaly in mouse. The high significant linkage was found at D6Mit230 on chromosome 6, and other significant linkages were found around D7Mit105 on chromosome and D8Mit65 on chromosome 8. These results suggest that the major gene(s) responsible for mouse root formation are located in these regions.