Fig 2: Ctnnd1 knockouts in Xenopus give rise to altered morphogenesis of the muscles and heart. (A) Immunofluorescent staining for collagen 2 (col2, magenta), muscle/pax2 (white) and nuclei (DAPI, blue); (a, anterior; p, posterior; d, dorsal; v, ventral). (A) (a, e) A lateral view of col2-positive branchial cartilages in UIC (a) and p120 CRISPR mutant (e) reveals the hypoplasia of mutant cartilages; however, cell morphology appears normal in p120 CRISPR mutants (h) (d and h, white arrowheads). (A) (b, c, f and g) Pax2-expressing muscles revealed a defect in the fibril organization of the rectus abdominus muscle in the p120 CRISPR tadpoles (f, white arrowhead) compared with the UIC muscles (b, white arrowhead); note insets in (c, g). (B) Ventral views of hearts of stage 46 tadpoles. Immunofluorescent staining for p120-catenin (green), E-cadherin (red) and DNA (blue). (B) (i–m) Controls; (n–r) p120 CRISPR mutant tadpoles. Morphologic defects are evident in the size of the heart and directionality of the loops (compare control heart (i) to mutant heart (n), yellow-dashed outlines). (B) (k, p) p120-catenin is strongly expressed in the heart of UIC tadpoles (k) but is lost in p120 CRISPR tadpoles (p). (B) (l, q) Note the absence of E-cadherin in the control and mutant hearts. Scale bars = 100 µm.

Fig 3: Pedigrees and identification of CTNND1 variants. (A) Pedigrees of individuals with identified variants. Family identifications, in brackets [A-I], and patient identification numbers correlate with Table 1. Filled boxes indicate affected individuals demonstrating collective phenotypes described in our cohort. A blank box with a vertical black line indicates an asymptomatic carrier (clinically unaffected). A box with an oblique line indicates a deceased individual. Lightly shaded boxes indicate individuals affected with one or more of the conditions described. (B) Schematic representation of the human p120-catenin protein structure and its domains. The variants described in our cohort are shown above the protein with a dark gray arrow. The light gray arrow with the (p.Arg315Cys) variant indicates the other CTNND1 mutation found in Patient 3 which was inherited from the unaffected father [A]. Arrows in blue, pink and brown represent the variants and their locations reported in Ghoumid et al. (2), Kievit et al. (1) and Cox et al. (3), respectively.

Fig 4: Clinical presentation of individuals with a CTNND1 mutation. Facial photos (frontal and profile) show craniofacial features of patients. Note the narrow up-slanting palpebral fissures in Patients 3, 4 and 7–13; the hooded eyelids in Patients 3, 4 and 8–13; telecanthus in Patients 3, 4 and 9–13; the high arched eyebrows in Patients 1, 2, 6–8 and 11–13 and the thin lateral eyebrows in Patients 1 and 5–11. Patients 1 and 4 had missing eyelashes medially from the inner canthus; Patients 1, 2, 5 and 7 have distichiasis (double row of lashes), and mild ectropion of the lower eyelids was seen in Patients 1, 5 and 6. As evident, no patient shows signs of hair sparsity. Most patients had wide nasal bridges with broad nasal tips, while Patients 1, 2, 8 and 11 were also diagnosed with congenital choanal atresia. Patients 1, 2, 7–9, 11 and 12 showed thin upper lips, and while mid-face hypoplasia was observed, Patients 1, 3, 8, 11 and 13 also had mandibular prognathism. Scars from cleft lip operations are seen in Patients 7 and 9–13. Patient 3 was born with a sub-mucous cleft palate, a bifid uvula and VPI.

Fig 5: Model of CTNND1 function in systemic disease. (A) CTNND1 mutations are not only implicated in conditions that affect epithelial structures but also systemic conditions that originate from mesenchymal roles of p120-catenin. Structures in pink circles have been described in previous publications on CTNND1 (1,2); structures in blue circles have been implicated previously in CTNND1-related disorders (1,2) and in this study. Structures in yellow circles have been identified in this study. (B) BCD is primarily due to disturbances in E-cadherin/p120 interactions. The inclusion of other organ systems described here highlights the involvement of other known molecular functions of p120, such as its role in the WNT signalling pathway and its interactions with Rho-GTPases, demonstrating its mesenchymal roles in producing these systemic conditions.