UNILATERAL CLEFT-LIP WITH OR WITHOUT CLEFT-PALATE AND HANDEDNESS - ISTHERE AN ASSOCIATION

Objective: The purpose of this study was to investigate the possibilit y of a relationship between the side of occurrence of unilateral cleft ing of the lip and/or palate and handedness, also taking into account the type of the Initial cleft condition, a factor that has not been ad equately assessed in previous studies. Design: This was a retrospectiv e study. Setting: Division of Orthodontics, The Hospital for Sick Chil dren, Toronto, Canada, and Cleft Lip and Palate Program, Children's Ho spital, Winnipeg, Canada.Participants: Subjects were 289 patients (176 males and 113 females)9 years of age or older presenting with a histo ry of unilateral clefts of the lip with or without the palate. Of thes e patients, 217 were recruited from the patient pool of the Orthodonti c Clinic at the Hospital for Sick Children in Toronto. The remaining 7 2 were selected from the registry of the Cleft Lip and Palate Program of the Children's Hospital in Winnipeg. Any syndromic cases were exclu ded from the sample. Main Outcome Measures: Assessment of handedness w as performed by asking the patients to fill out a multi-item questionn aire in which patients were asked to identify which hand they would us e for different tasks. The side and type of the initial cleft conditio n were identified by reviewing each patient's hospital chart and by cr oss-referencing with clinical examination. Statistical evaluation of t he results was performed by using the chi-square test. Results: There was a significantly larger number of left-sided clefts (198) in the sa mple than right-sided clefts (91), (p < .001). The proportion of left- sided clefts among left-handers (84.6%) was higher than that among rig ht-handers (66.8%). However, the relationship between side of cleft an d handedness was not statistically significant (p = .185). Clefts of t he primary palate only seemed to occur on the left side 3.5 times more often than on the right, whereas the corresponding ratio of left:righ t manifestation for clefts of the primary and secondary palate was 1.8 :1. The difference was statistically significant (p < .05). Conclusion : The findings of this study confirm the affinity of unilateral clefts for the left side but suggest that there are differences between clef ts of the primary palate only and clefts of the primary and secondary palate. Also, non-right-handed patients show a greater predilection fo r having a cleft on the left side than do right-handed patients.