Epidemiology of Cleft Lip and Palate [chapter]

Mairaj K. Ahmed, Anthony H. Bui, Emanuela Taioli
2017 Designing Strategies for Cleft Lip and Palate Care  
Orofacial cleft (OFC) anomalies are amongst the most common congenital anomalies and the most common craniofacial anomalies. Despite their poorly characterized etiologies, cases of OFC are usually grouped by epidemiological studies as cleft lip, with or without cleft palate (CL/P), and cleft palate alone (CPO). Incidence of CL/P and CPO differs according to gender and ancestry and may vary widely across studies. Cases of OFC are characterized as either "syndromic" or "nonsyndromic," with
more » ... romic," with further classification of nonsyndromic cases into isolated cases and cases that present with additional malformations. The genetic bases for many syndromic cases of OFC have been previously elucidated. Genetic associations have been described for nonsyndromic OFC as well. Importantly, etiology of OFC is known to involve interaction between genetic and environmental factors, including maternal nutrition and exposure to teratogenic agents. Furthermore, evidence points toward epigenetic as well as genetic factors influencing OFC etiology. Recent studies have begun to explore the association between CL/P and cancer. These studies report higher incidence of cancer among patients with CL/P and their family members as well as identification of common genetic markers mediating this increased risk, although much remains unknown about this link. palate alone (CPO) even though the etiology of each may be unique. Whether or not CL/P and CPO have distinct etiology and should be combined in investigations is under debate. It is often found in epidemiological studies that CL/P and CPO is considered underneath the umbrella of either "syndromic" or "nonsyndromic." Furthermore, "nonsyndromic" CL/P and CPO cases can be subgrouped into those that are isolated or those that have additional malformations that do not form a recognizable syndrome. Relatively, the etiology of nonsyndromic cases of CL/P and CPO is lesser known compared to those found identified with a syndrome. Due to the poorly characterized etiology of CL/P and CPO, in general, there is still debate for the best method of grouping CL/P and CPO in epidemiological studies, but the most common current classifications are used to help determine associations and thus help the clinician with their diagnosis and subsequent treatment. The genetic basis for many syndromic cases of CL/P and CPO are well-described. Evidence for genetic factors underlying nonsyndromic CL/P and CPO has begun to materialize as well. While less well-described, it is also known that epigenetic modifications can play a role in the development of CL/P and CPO. Recently, the association between OFC and cancer has been explored, with evidence suggesting existence of a link between the presence of OFC in patients and risk of cancer in these patients and/or their families.
doi:10.5772/67165 fatcat:gddyhg2d7zcwvaiz6lxpaeieta