ABSTRACT
Adams-Oliver syndrome (AOS) is a rare congenital disease characterized by aplasia cutis congenita (ACC) and terminal transverse limb defects (TTLD). It shows significant genetic heterogeneity and can be transmitted by autosomal dominant or recessive inheritance. Recessive inheritance is associated with mutations of DOCK6 or EOGT; however, only few cases have been published so far. We present two families with EOGT-associated AOS. Due to pseudodominance in one family, the recognition of the recessive inheritance pattern was difficult. We identified two novel AOS-causing mutations (c.404G>A/p.Cys135Tyr and c.311+1G>T). The phenotype in the presented families was dominated by large ACC, whereas TTLD were mostly subtle or even absent and no major malformations occured. Our observations along with the previously published cases indicate that the two types of recessive AOS (EOGT- vs. DOCK6-associated) differ significanty regarding the frequency of neurologic or ocular deficits.
Subject(s)
Ectodermal Dysplasia/diagnosis , Ectodermal Dysplasia/genetics , Genetic Association Studies , Genetic Predisposition to Disease , Limb Deformities, Congenital/diagnosis , Limb Deformities, Congenital/genetics , Mutation , N-Acetylglucosaminyltransferases/genetics , Scalp Dermatoses/congenital , Child , Consanguinity , Exons , Genetic Association Studies/methods , Humans , Infant , Magnetic Resonance Imaging , Male , Pedigree , Phenotype , Scalp Dermatoses/diagnosis , Scalp Dermatoses/geneticsABSTRACT
Adams-Oliver syndrome (AOS) is a rare developmental disorder, characterized by scalp aplasia cutis congenita (ACC) and transverse terminal limb defects (TTLD). Autosomal dominant forms of AOS are linked to mutations in ARHGAP31, DLL4, NOTCH1 or RBPJ, while DOCK6 and EOGT underlie autosomal recessive inheritance. Data on the frequency and distribution of mutations in large cohorts are currently limited. The purpose of this study was therefore to comprehensively examine the genetic architecture of AOS in an extensive cohort. Molecular diagnostic screening of 194 AOS/ACC/TTLD probands/families was conducted using next-generation and/or capillary sequencing analyses. In total, we identified 63 (likely) pathogenic mutations, comprising 56 distinct and 22 novel mutations, providing a molecular diagnosis in 30% of patients. Taken together with previous reports, these findings bring the total number of reported disease variants to 63, with a diagnostic yield of 36% in familial cases. NOTCH1 is the major contributor, underlying 10% of AOS/ACC/TTLD cases, with DLL4 (6%), DOCK6 (6%), ARHGAP31 (3%), EOGT (3%), and RBPJ (2%) representing additional causality in this cohort. We confirm the relevance of genetic screening across the AOS/ACC/TTLD spectrum, highlighting preliminary but important genotype-phenotype correlations. This cohort offers potential for further gene identification to address missing heritability.
