Craniofrontonasal syndrome (CFNS) is an X-linked craniofacial disorder with an unusual manifestation pattern, in which affected females show multiple skeletal malformations, whereas the genetic defect causes no or only mild abnormalities in male carriers. Recently, we have mapped a gene for CFNS in the pericentromeric region of the X chromosome that contains the EFNB1 gene, which encodes the ephrin-B1 ligand for Eph receptors. Since Efnb1 mutant mice display a spectrum of malformations and an unusual inheritance reminiscent of CFNS, we analyzed the EFNB1 gene in three families with CFNS. In one family, a deletion of exons 2-5 was identified in an obligate carrier male, his mildly affected brother, and in the affected females. In the two other families, missense mutations in EFNB1 were detected that lead to amino acid exchanges P54L and T111I. Both mutations are located in multimerization and receptor-interaction motifs found within the ephrin-B1 extracellular domain. In all cases, mutations were found consistently in obligate male carriers, clinically affected males, and affected heterozygous females. We conclude that mutations in EFNB1 cause CFNS.

ORIGINAL RESEARCH ARTICLEPurpose: Mowat-Wilson syndrome (MWS) is a rare intellectual disability/multiple congenital anomalies syndrome caused by heterozygous mutation of the ZEB2 gene. It is generally underestimated because its rarity and phenotypic variability sometimes make it difficult to recognize. Here, we aimed to better delineate the phenotype, natural history, and genotype-phenotype correlations of MWS. Methods:In a collaborative study, we analyzed clinical data for 87 patients with molecularly confirmed diagnosis. We described the prevalence of all clinical aspects, including attainment of neurodevelopmental milestones, and compared the data with the various types of underlying ZEB2 pathogenic variations.Results: All anthropometric, somatic, and behavioral features reported here outline a variable but highly consistent phenotype. By presenting the most comprehensive evaluation of MWS to date, we define its clinical evolution occurring with age and derive suggestions for patient management. Furthermore, we observe that its severity correlates with the kind of ZEB2 variation involved, ranging from ZEB2 locus deletions, associated with severe phenotypes, to rare nonmissense intragenic mutations predicted to preserve some ZEB2 protein functionality, accompanying milder clinical presentations. Conclusion:Knowledge of the phenotypic spectrum of MWS and its correlation with the genotype will improve its detection rate and the prediction of its features, thus improving patient care.

Marinesco-Sjögren syndrome is a rare autosomal recessive multisystem disorder featuring cerebellar ataxia, early-onset cataracts, chronic myopathy, variable intellectual disability and delayed motor development. More recently, mutations in the SIL1 gene, which encodes an endoplasmic reticulum resident co-chaperone, were identified as the main cause of Marinesco-Sjögren syndrome. Here we describe the results of SIL1 mutation analysis in 62 patients presenting with early-onset ataxia, cataracts and myopathy or combinations of at least two of these. We obtained a mutation detection rate of 60% (15/25) among patients with the characteristic Marinesco-Sjögren syndrome triad (ataxia, cataracts, myopathy) whereas the detection rate in the group of patients with more variable phenotypic presentation was below 3% (1/37). We report 16 unrelated families with a total of 19 different SIL1 mutations. Among these mutations are 15 previously unreported changes, including single- and multi-exon deletions. Based on data from our screening cohort and data compiled from the literature we found that SIL1 mutations are invariably associated with the combination of a cerebellar syndrome and chronic myopathy. Cataracts were observed in all patients beyond the age of 7 years, but might be missing in infants. Six patients with SIL1 mutations had no intellectual disability, extending the known wide range of cognitive capabilities in Marinesco-Sjögren syndrome to include normal intelligence. Modestly constant features were somatic growth retardation, skeletal abnormalities and pyramidal tract signs. Examination of mutant SIL1 expression in cultured patient lymphoblasts suggested that SIL1 mutations result in severely reduced SIL1 protein levels irrespective of the type and position of mutations. Our data broaden the SIL1 mutation spectrum and confirm that SIL1 is the major Marinesco-Sjögren syndrome gene. SIL1 patients usually present with the characteristic triad but cataracts might be missing in young children. As cognitive impairment is not obligatory, patients without intellectual disability but a Marinesco-Sjögren syndrome-compatible phenotype should receive SIL1 mutation analysis. Despite allelic heterogeneity and many families with private mutations, the phenotype related to SIL1 mutations is relatively homogenous. Based on SIL1 expression studies we speculate that this may arise from a uniform effect of different mutations on protein expression.

The Shprintzen-Goldberg syndrome (SGS) is a disorder of unknown cause comprising craniosynostosis, a marfanoid habitus and skeletal, neurological, cardiovascular, and connective-tissue anomalies. There are no pathognomonic signs of SGS and diagnosis depends on recognition of a characteristic combination of anomalies. Here, we describe 14 persons with SGS and compare their clinical findings with those of 23 previously reported individuals, including two families with more than one affected individual. Our analysis suggests that there is a characteristic facial appearance, with more than two thirds of all individuals having hypertelorism, down-slanting palpebral fissures, a high-arched palate, micrognathia, and apparently low-set and posteriorly rotated ears. Other commonly reported manifestations include hypotonia in at least the neonatal period, developmental delay, and inguinal or umbilical hernia. The degree of reported intellectual impairment ranges from mild to severe. The most common skeletal manifestations in SGS were arachnodactyly, pectus deformity, camptodactyly, scoliosis, and joint hypermobility. None of the skeletal signs alone is specific for SGS. Our study includes 14 mainly German individuals with SGS evaluated over a period of 10 years. Given that only 23 other persons with SGS have been reported to date worldwide, we suggest that SGS may be more common than previously assumed.

Purpose Mowat-Wilson syndrome (MWS) is a genetic disease characterized by distinctive facial features, moderate to severe intellectual disability and congenital malformations including Hirschsprung disease, genital and eye anomalies and congenital heart defects, caused by haploinsufficiency of the ZEB2 gene. To date, no characteristic pattern of brain dysmorphology in MWS has been defined. Methods Through brain MRI analysis, we delineate a neuroimaging phenotype in 54 MWS patients with a proven ZEB2 defect, compare it with the features identified in a thorough review of published cases, and evaluate genotype-phenotype correlations. Results 96% of patients had abnormal MRI. The most common features were anomalies of corpus callosum (79.6% of cases), hippocampal abnormalities (77.8%), enlargement of cerebral ventricles (68.5%), white matter abnormalities (reduction of thickness 40.7%, localized signal alterations 22.2%). Other consistent findings were large basal ganglia, cortical and cerebellar malformations. Most features were underrepresented in the literature. We also found ZEB2 variations leading to synthesis of a defective protein to be favourable for psychomotor development and some epilepsy features, but also associated with corpus callosum agenesis. Conclusion This study delineates the spectrum of brain anomalies in MWS and at the same time adds new insights in elucidating the role of ZEB2 in neurodevelopment.