6761 6761 *Figure 50.1 (a) Unilateral 6762 6762 cleft lip. (b) Bilateral cleft 6763 6763 lip. (c) Isolated cleft palate.* 6764 6764 6765 6765 (a) 6766 6766 6767 6767 6768 6768 ![A diagram illustrates the mouth's anatomy, labeling the lips, alveolar ridge, hard palate, and soft palate regions.](https://cdn.orris.care/cdss_images/5e25fc162dab036c67b8cedefa5ba0371638abf007ae316a1913360046ef98df.png) 6769 6769 6770 6770 (b) 6771 6771 6772 6772 6773 6773

Class	Description
I	Soft palate only
II	Hard and soft palate to the incisive foramen
III	Complete unilateral of soft, hard, lip and alveolar ridge
IV	Complete bilateral of soft, hard and/or lip and alveolar ridge

6774 6774 6775 6775 *Figure 50.2 (a) The LAHSHAL code. (b) The Veau classification system.* 6776 6776 6777 6777 adopted: even when the same system is being used, clinicians 6778 6778 may interpret the findings inconsistently. 6779 6779 6780 6780 In the UK, national audit data are collected for outcomes in 6781 6781 unilateral cleft lip and palate (UCLP), thus allowing intercentre 6782 6782 comparison. Cleft lip and/or palate is more common in males, 6783 6783 whereas isolated cleft palate is more common in females. In 6784 6784 UCLP the condition affects the left side in 60% of cases. 6785 6785 6786 6786 6787 6787 ## Summary box 50.1 6788 6788 6789 6789 6790 6790 ## Overview of cleft lip and palate 6791 6791 6792 6792 • Cleft lip and/or palate has two main phenotypes 6793 6793 • Cleft palate is more common in females and cleft lip and/or palate is more common in males 6794 6794 • The incidence/prevalence demonstrates geographical variation 6795 6795 • There are simple classification systems that describe phenotype 6796 6796 6797 6797 6798 6798 ## Aetiology 6799 6799 6800 6800 Non-syndromic cleft lip and/or palate may present as new 6801 6801 diagnosis within a family or with a clear family history. A 6802 6802 family history of cleft lip and palate in which a first-degree 6803 6803 relative is affected increases the risk of subsequent cleft cases 6804 6804 in the family, supporting the theory that there are underlying 6805 6805 genetic mutations contributing to the aetiology. Isolated cleft 6806 6806 palate is more commonly associated with a syndrome than 6807 6807 cleft lip and palate and isolated cleft lip. Over 150 named 6808 6808 syndromes are associated with cleft lip and palate, although 6809 6809 Stickler (ophthalmic and musculoskeletal abnormalities), 6810 6810 DiGeorge (cardiac/thymic anomalies), Down, Apert and 6811 6811 Treacher Collins syndromes are most frequently encountered. 6812 6812 [... Output truncated due to length. 1525 tokens/4753 characters removed ...]