Mandibular-pelvic-patellar syndrome is a novel PITX1-related disorder due to alteration of PITX1 transactivation ability.

PITX1 is a homeobox transcription factor essential for hindlimb morphogenesis. Two PITX1-related human disorders have been reported to date: PITX1 ectopic expression causes Liebenberg syndrome, characterized by malformation of upper limbs showing a "lower limb" appearance; PITX1 deletions or missense variation cause a syndromic picture including clubfoot, tibial hemimelia, and preaxial polydactyly. We report two novel PITX1 missense variants, altering PITX1 transactivation ability, in three individuals from two unrelated families showing a distinct recognizable autosomal dominant syndrome, including first branchial arch, pelvic, patellar, and male genital abnormalities. This syndrome shows striking similarities with the Pitx1-/- mouse model. A partial phenotypic overlap is also observed with Ischiocoxopodopatellar syndrome caused by TBX4 haploinsufficiency, and with the phenotypic spectrum caused by SOX9 anomalies, both genes being PITX1 downstream targets. Our study findings expand the spectrum of PITX1-related disorders and suggest a common pattern of developmental abnormalities in disorders of the PITX1-TBX4-SOX9 signaling pathway.

Blepharocheilodontic syndrome is a CDH1 pathway-related disorder due to mutations in CDH1 and CTNND1.

PURPOSE: Blepharocheilodontic (BCD) syndrome is a rare autosomal dominant condition characterized by eyelid malformations, cleft lip/palate, and ectodermal dysplasia. The molecular basis of BCD syndrome remains unknown. METHODS: We recruited 11 patients from 8 families and performed exome sequencing for 5 families with de novo BCD syndrome cases and targeted Sanger sequencing in the 3 remaining families. RESULTS: We identified five CDH1 heterozygous missense mutations and three CTNND1 heterozygous truncating mutations leading to loss-of-function or haploinsufficiency. Establishment of detailed genotype-phenotype correlations was not possible because of the size of the cohort; however, the phenotype seems to appear more severe in case of CDH1 mutations. Functional analysis of CDH1 mutations confirmed their deleterious impact and suggested accelerated E-cadherin degradation. CONCLUSION: Mutations in CDH1 encoding the E-cadherin were previously reported in hereditary diffuse gastric cancer as well as in nonsyndromic cleft lip/palate. Mutations in CTNND1 have never been reported before. The encoded protein, p120ctn, prevents E-cadherin endocytosis and stabilizes its localization at the cell surface. Conditional deletion of Cdh1 and Ctnnd1 in various animal models induces features reminiscent of BCD syndrome and underlines critical role of the E-cadherin-p120ctn interaction in eyelid, craniofacial, and tooth development. Our data assert BCD syndrome as a CDH1 pathway-related disorder due to mutations in CDH1 and CTNND1 and widen the phenotypic spectrum of E-cadherin anomalies.Genet Med advance online publication 09 March 2017.

Acro-dermato-ungual-lacrimal-tooth-like syndrome: report of a family with variable expression.

We report the case of a young boy with fine hair, mild nail dysplasia, blocked nasolacrimal ducts, absence of central incisors, bilateral oligodactyly of feet and anal stenosis. His father showed the same spectrum of anomalies with mild expression. He had mild nail dysplasia, blocked nasolacrimal ducts, inferior dental cysts with consequent premature tooth loss, frequent dental decays consequent to enamel abnormality and cutaneous syndactyly of the second and third right toe. The acro-dermato-ungual-lacrimal-tooth syndrome was suspected and molecular analysis of the P63 gene was performed, but no mutation was found. Although P63 gene analysis was negative, we think that both cases show clinical overlap with the acro-dermato-ungual-lacrimal-tooth syndrome and confirm the wide expression of this condition, even in the same family.