| Objective1.Identifing the gene variation associated with non-syndromic cleft lip and palate in a Chinese family using Linked-Read technology.2.1 To investigate horizontal maxillary osteotomy stability after using bone grafts for the treatment of patients with unilateral cleft lip and palate.2.2 To present the clinical results and complications of a two-stage surgical approach using a modified external distraction system that consists of maxillary distraction and then maxillary fixation.Methods1.In this study,we analyzed a non-syndromic cleft lip and palate multiplex family,collected the epidemiological information,and mapped the pedigree.The genomic DNA were obtained from whole blood sample.Linked-Read sequencing was performed to achieve genome-wide variants.Based on hg38,Long Ranger software was used to map the variants,ANNOVAR was used to annotate the variants.The candidate genes variants were selected according to the location of the variants,allele frequencies,function,conservation,disease risk,as well as their association with craniofacial development and cleft lip and palate.2.1 Fifty-eight patients with maxillary hypoplasia were included,who required a maxillary advancement of 6 to 9 mm.The test group was comprised of 28 patients who underwent mandibular outer cortex bone grafting in the gaps created by a modified Le Fort I osteotomy.The control group was comprised of 30 patients who underwent a traditional Le Fort I osteotomy without bone grafts.2.2 We treated eleven patients with cleft lip and palate by two-stage maxillary distraction osteogenesis.Lateral cephalograms taken before the first operation,after distraction,two weeks after the second operation,and one year after treatment were used to examine maxillofacial morphology.Five patients were treated with transverse expansion at the same time.Computer tomography was taken before and after consolidation to analyze the effect of maxillary expansion.Velopharyngeal function was evaluated by a speech therapist.Results1.we identified two candidate variants for this non-syndromic cleft lip and palate multiplex family including a missense of AXIN2(c.2018G>A,p.S673F)and a deletion of 155 kilo-base region overlapping ADAM3A and ADAM5(chr8,39374555-39529710).2.1 In the test group,the mean maxillary horizontal advancement was 7.13±0.7mm(range:6.01-8.23 mm),and the mean postoperative horizontal relapse was 25.07±6.64%.In the CG,the mean maxillary horizontal advancement was 6.90±0.55mm(range:6.05-7.39 mm),and the mean postoperative horizontal relapse was 24.89+4.25%.There were no significant betweengroup differences in the mean horizontal relapses.2.2 The mean movements of the maxilla forwards and downwards at Point A were 13.9mm and 7.7mm at the completion of distraction and those at Point B were 5.3mm backwards and 8.5mm downwards.Clockwise rotation was observed in maxilla and mandible.Mouth opening was limited at this time.After the maxilla was fixed,compared with pre-operation,Point A moved 10.1mm anteriorly and 3.4mm inferiorly and Point B moved 2.4mm posteriorly and 4.7mm inferiorly.Limitation of mouth opening was relieved after maxillary fixation.The mean relapse of Point A one year postoperatively was 22.2%horizontally and 51.6%vertically.After expansion in 5 patients,the width of dental arch was significantly increased.The mean width between cusps of canines increased 6.4mm,and between mesial-buccal cusps of the first molars increased 6.2mm.Velopharyngeal function was unchanged by the operation.Conclusion 1.The two gene variants may be involved in the etiology of oral clefts.2.1 The use of mandibular outer cortex bone grafts in patients with unilateral cleft lip and palate did not increase postoperative stability when the maxillary advancement was 6 to 9 mm.2.2 We conclude that the method had advantages that included the short duration of wearing distractors and increased acceptance by patients.The modified external device advanced the midface sufficiently. |
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