带有/不带裂口的裂口唇裂（Cl/p）是最常见的先天缺陷之一，在全球范围内大约1/700 Live出生。通过遗传和流行病学研究，在CL/P中已经确定了广泛的遗传和环境危险因素。CleftgenedB是与人类和小鼠中CL/P相关的基因的第一个综合数据库。CleftgenedB显示出在10个真核物种中注释的裂口基因（最初在人类或小鼠中鉴定出来），并且来自生物信息学分析的信息（例如网络，KEGG，GO，microRNA）。因此，裂口可以作为研究颅面发育和颅面先天缺陷的有用多物种资源。CleftgenedB将被更新并扩展到其他颅面出生缺陷。
嘴唇形成始于人类妊娠32天的胚胎，当表面外胚层在额叶过程的腹侧外侧双侧增厚以形成鼻腔座。上颌过程在内侧增长和推动，而内侧鼻腔过程的腹外侧生长将圆形鼻坑转化为人类妊娠35天的背尖裂。在人类和小鼠的胚胎日E12.5中，妊娠48天形成上唇。
Palate formation begins with two primordia, the primary and secondary palates, as early as the 6th week of gestation in humans and at E11.5 in mice. The intermaxillary segment, which is derived from the distal part of the medial nasal processes, starts outgrowing toward the oral cavity to form the primary palate at E12.5 in mice and at the 7th week of gestation in humans. Following initiation and growth of the maxillary process, the palatal shelves, which become the secondary palate, first grow vertically along the lateral sides of the tongue. Around week 7-9 of gestation in humans and E14.0 in mice, the palatal shelves elevate into a horizontal position above the dorsum of the tongue, following the growth of the jaws and descent of the tongue. The fusion between the primary and secondary palates is also completed by E16.5 in mice and by the 12th week of gestation in humans. The palatal shelves are indicated in red.
小鼠裂口唇（Cl）和/或裂口（CP）分为三组：仅唇唇（Clo;又称孤立的Cl），带left裂（Clp）（Clp）的left唇裂（CLP）和cleft裂（CPO; CPO; A.K.A.孤立的CP）。CLO进一步分为单侧和双侧CL，而CPO分为完整和部分CP。部分CP进一步分类为主要的pa（口感前区），次生口感（口感的多数部分），cleft裂软pa（pape的后部区域）和粘膜left裂（持久）（持久）（持久）mee或不完整的上颌骨过程的融合）。在人类中，带有/不带left裂（Cl/ p）的唇裂是最常用的术语来描述面部裂缝。Cl/P包括CLO和CLP。显示了带有指示表型的口服和额叶视图。