Although the aetiology of non-syndromic orofacial clefts (nsOFCs) is usually multifactorial, syndromic OFCs (syOFCs) are often caused by single mutations in known genes. Some syndromes, e.g., Van der Woude syndrome (VWS1; VWS2) and X-linked cleft palate with or without ankyloglossia (CPX), show only minor clinical signs in addition to OFC and are sometimes difficult to differentiate from nsOFCs. We recruited 34 Slovenian multi-case families with apparent nsOFCs (isolated OFCs or OFCs with minor additional facial signs). First, we examined IRF6, GRHL3, and TBX22 by Sanger or whole exome sequencing to identify VWS and CPX families. Next, we examined 72 additional nsOFC genes in the remaining families. Variant validation and co-segregation analysis were performed for each identified variant using Sanger sequencing, real-time quantitative PCR and microarray-based comparative genomic hybridization. We identified six disease-causing variants (three novel) in IRF6, GRHL3, and TBX22 in 21% of families with apparent nsOFCs, suggesting that our sequencing approach is useful for distinguishing syOFCs from nsOFCs. The novel variants, a frameshift variant in exon 7 of IRF6, a splice-altering variant in GRHL3, and a deletion of the coding exons of TBX22, indicate VWS1, VWS2, and CPX, respectively. We also identified five rare variants in nsOFC genes in families without VWS or CPX, but they could not be conclusively linked to nsOFC.

Mutations in the T-Box transcription factor gene TBX22 are found in X-linked Cleft Palate with or without Ankyloglossia syndrome (CPX syndrome). In addition to X-linked inheritance, ankyloglossia, present in the majority of CPX patients, is an important diagnostic marker, but it is frequently missed or unreported, as it is a "minor" feature. Other described anomalies include cleft lip, micro and/or hypodontia, and features of CHARGE syndrome. We conducted whole exome sequencing (WES) on 22 individuals from 17 "a priori" non-syndromic cleft lip and/or cleft palate (CL/P) families. We filtered the data for heterozygous pathogenic variants within a set of predefined candidate genes. Two canonical splice-site mutations were found in TBX22. Detailed re-phenotyping of the two probands and their families unravelled orofacial features previously not associated with the CPX phenotypic spectrum: choanal atresia, Pierre-Robin sequence, and overgrowths on the posterior edge of the hard palate, on each side of the palatal midline. This study emphasizes the importance of WES analysis in familial CLP cases, combined with deep (reverse) phenotyping in "a priori" non-syndromic clefts.

Ankyloglossia is a congenital oral anomaly characterized by the presence of a hypertrophic and short lingual frenulum. Mutations in the gene encoding the transcription factor TBX22 have been involved in isolated ankyloglossia and X-linked cleft palate. The knockout of Lgr5 in mice results in ankyloglossia. Here, we report a five-generation family including patients with severe ankyloglossia and missing lower central incisors. Two members of this family also exhibited congenital anorectal malformations. In this report, male-to-male transmission was in favor of an autosomal dominant inheritance, which allowed us to exclude the X-linked TBX22 gene. Linkage analysis using short tandem repeat markers located in the vicinity of LGR5 excluded this gene as a potential candidate. These results indicate genetic heterogeneity for ankyloglossia. Further investigations with additional families are required in order to identify novel candidate genes.

Ankyloglossia or tongue-tie is a congenital anomaly affecting the tongue, which is characterized by thick, short lingual frenulum. This condition causes many difficulties such as limited tongue protrusion, breastfeeding difficulties, speech impairment and lack of self-confidence. It is very rarely associated with any other congenital craniofacial disorders such as cleft lip, X-linked cleft palate, Van der Woude syndrome, Smith-Lemli-Opitz syndrome, Orofacial digital syndrome, Beckwith Weidman syndrome or Simpson-Golabi-Behmel syndrome. This article presents a rare case of ankyloglossia associated with cleft lip treated with diode laser in a 12-year-old Indian boy who had undergone surgical correction of associated cleft lip soon after birth. Correction of ankyloglossia at a young age would lead to enhanced phonetics, improved oral hygiene, and overall personality development.

The aetiology of nonsyndromic cleft lip with or without cleft palate (NSCLP) is complex and involves both genetic and environmental risk factors. Classical research has shown that growth and patterning of the developing palatal shelves depend on epithelial-mesenchymal interactions. Expression of several signalling molecules and transcription factors in the anterior palate during early palate development has been documented. TBX22 encodes a T-box containing transcription factor and mutations in this gene are responsible for X-linked cleft palate and ankyloglossia. In the present study, we analysed two TBX22 promoter rs7055763 and rs41307258 single-nucleotide polymorphisms (SNPs) in 173 patients with NSCLP and 176 normal controls of south Indian origin using Kbioscience KASPar chemistry, which is a competitive allele-specific PCR SNP genotyping system. As the SNPs are located on chromosome X, the association analysis was carried out separately in men and women. Significant associations of rs7055763 (P=0.034) and rs41307258 (P=0.022) with NSCLP were found only in women. Both polymorphisms increased the risk for NSCLP in the heterozygous and homozygous variant state, but this was not significant. Both SNPs were not associated with a risk for NSCLP in men. Pair-wise linkage disequilibrium between rs7055763 and rs41307258 was strong and significant (D'=0.97 and r2=0.77). Only three haplotypes were observed with an estimated frequency more than 5%. Haplotype AA, which carries both mutant alleles (rs7055763 A - rs41307258 A), was significantly associated with an increased risk of NSCLP in women, but not in men. Our study showed a significant role of TBX22 promoter polymorphisms (rs7055763 and rs41307258) in the pathogenesis of NSCLP and reinforces the previous findings of a strong link between X-linked genes and orofacial clefts.