Mutations in the Epithelial Cadherin-p120-Catenin Complex Cause Mendelian Non-Syndromic Cleft Lip with or without Cleft Palate.

Non-syndromic cleft lip with or without cleft palate (NS-CL/P) is one of the most common human birth defects and is generally considered a complex trait. Despite numerous loci identified by genome-wide association studies, the effect sizes of common variants are relatively small, with much of the presumed genetic contribution remaining elusive. We report exome-sequencing results in 209 people from 72 multi-affected families with pedigree structures consistent with autosomal-dominant inheritance and variable penetrance. Herein, pathogenic variants are described in four genes encoding components of the p120-catenin complex (CTNND1, PLEKHA7, PLEKHA5) and an epithelial splicing regulator (ESRP2), in addition to the known CL/P-associated gene, CDH1, which encodes E-cadherin. The findings were also validated in a second cohort of 497 people with NS-CL/P, comprising small families and singletons with pathogenic variants in these genes identified in 14% of multi-affected families and 2% of the replication cohort of smaller families. Enriched expression of each gene/protein in human and mouse embryonic oro-palatal epithelia, demonstration of functional impact of CTNND1 and ESRP2 variants, and recapitulation of the CL/P spectrum in Ctnnd1 knockout mice support a causative role in CL/P pathogenesis. These data show that primary defects in regulators of epithelial cell adhesion are the most significant contributors to NS-CL/P identified to date and that inherited and de novo single gene variants explain a substantial proportion of NS-CL/P.

A human homeotic transformation resulting from mutations in PLCB4 and GNAI3 causes auriculocondylar syndrome.

Auriculocondylar syndrome (ACS) is a rare, autosomal-dominant craniofacial malformation syndrome characterized by variable micrognathia, temporomandibular joint ankylosis, cleft palate, and a characteristic "question-mark" ear malformation. Careful phenotypic characterization of severely affected probands in our cohort suggested the presence of a mandibular patterning defect resulting in a maxillary phenotype (i.e., homeotic transformation). We used exome sequencing of five probands and identified two novel (exclusive to the patient and/or family studied) missense mutations in PLCB4 and a shared mutation in GNAI3 in two unrelated probands. In confirmatory studies, three additional novel PLCB4 mutations were found in multigenerational ACS pedigrees. All mutations were confirmed by Sanger sequencing, were not present in more than 10,000 control chromosomes, and resulted in amino-acid substitutions located in highly conserved protein domains. Additionally, protein-structure modeling demonstrated that all ACS substitutions disrupt the catalytic sites of PLCB4 and GNAI3. We suggest that PLCB4 and GNAI3 are core signaling molecules of the endothelin-1-distal-less homeobox 5 and 6 (EDN1-DLX5/DLX6) pathway. Functional studies demonstrated a significant reduction in downstream DLX5 and DLX6 expression in ACS cases in assays using cultured osteoblasts from probands and controls. These results support the role of the previously implicated EDN1-DLX5/6 pathway in regulating mandibular specification in other species, which, when disrupted, results in a maxillary phenotype. This work defines the molecular basis of ACS as a homeotic transformation (mandible to maxilla) in humans.

Localization of the supraorbital, infraorbital, and mental foramina using palpable, bony landmarks.

The purpose of this study was to locate the infraorbital, supraorbital, and mental foramina by using palpable anatomical landmarks that are conducive to surgical use. Fourteen embalmed cadavers (27 sides) were dissected to expose the supraorbital, infraorbital, and mental foramina. Measurements were made from the lateral orbital rim at the zygomaticofrontal (ZF) suture to both the supraorbital and infraorbital foramina. The distance from the inferior orbital rim at the zygomaticomaxillary (ZM) suture to both foramina was also measured. The distance to the mental foramen was measured from the angle and the inferior border of the mandible. The supraorbital foramen was located 26.2 +/- 2.8 mm medial and 13.5 +/- 3.7 mm superior to the ZF suture. The infraorbital foramen was located 23.8 +/- 3.1 mm medial and 30.9 +/- 3.8 mm inferior to the ZF suture, on average. Vertical measurements made from the ZM suture to the supraorbital foramen averaged 34.4 +/- 3.6 mm and from the ZM suture to the infraorbital foramina averaged 7.6 +/- 2.2 mm. The mental foramen was 64.2 +/- 6.4 mm medial to the angle of the mandible and 12.9 +/- 1.6 mm superior to the inferior border of the mandible. This study provides data that may be useful in predicting the location of the supraorbital, infraorbital, and mental foramina using palpable landmarks. These data may be particularly helpful for surgery in patients with missing teeth or fractures of the maxillary bone. Clin. Anat., 2010. (c) 2009 Wiley-Liss, Inc.

Expansion of the spectrum of ITGB6-related disorders to adolescent alopecia, dentogingival abnormalities and intellectual disability.

Alopecia with mental retardation (APMR) is a very rare disorder. In this study, we report on a consanguineous Pakistani family (AP91) with mild-to-moderate intellectual disability, adolescent alopecia and dentogingival abnormalities. Using homozygosity mapping, linkage analysis and exome sequencing, we identified a novel rare missense variant c.898G>A (p.(Glu300Lys)) in ITGB6, which co-segregates with the phenotype within the family and is predicted to be deleterious. Structural modeling shows that Glu300 lies in the ß-propeller domain, and is surrounded by several residues that are important for heterodimerization with α integrin. Previous studies showed that ITGB6 variants can cause amelogenesis imperfecta in humans, but patients from family AP91 who are homozygous for the c.898G>A variant present with neurological and dermatological features, indicating a role for ITGB6 beyond enamel formation. Our study demonstrates that a rare deleterious variant within ITGB6 causes not only dentogingival anomalies but also intellectual disability and alopecia.