The revised ghent nosology; reclassifying isolated ectopia lentis.

Inherited ectopia lentis (EL) is most commonly caused by Marfan syndrome (MFS), a multisystemic disorder caused by mutations in FBN1. Historically the diagnosis for patients with EL who have no systemic features of MFS is isolated EL (IEL). However, the Ghent nosology for MFS was updated in 2010 and made some important alterations. In particular, patients with EL and a FBN1 mutation are now categorically diagnosed with MFS, if their mutation has previously been described with aortic dilation/dissection. This carries significant systemic implications, as many patients previously diagnosed with IEL are now reclassified. We provide a review of all published cases of IEL caused by FBN1 mutations over the last 20 years to assess what impact the new Ghent nosology has on these. Indeed, 57/123 probands (46.3%) are now classified as MFS according to the revised Ghent nosology and 37/96 mutations (38.5%) reported to cause isolated EL have also been found in patients with aortic dilation/dissection. These findings suggest that EL caused by mutations in FBN1 is actually part of a spectrum of fibrillinopathies with MFS, and the term 'IEL' should be avoided in such cases.

A phenotypic screen of Marfan syndrome iPSC-derived vascular smooth muscle cells uncovers GSK3ß as a new target.

Marfan syndrome (MFS) is a rare connective tissue disorder caused by mutations in FBN1. Patients with MFS notably suffer from aortic aneurysm and dissection. Despite considerable effort, animal models have proven to be poorly predictive for therapeutic intervention in human aortic disease. Patient-derived induced pluripotent stem cells can be differentiated into vascular smooth muscle cells (VSMCs) and recapitulate major features of MFS. We have screened 1,022 small molecules in our in vitro model, exploiting the highly proteolytic nature of MFS VSMCs, and identified 36 effective compounds. Further analysis identified GSK3ß as a recurring target in the compound screen. GSK3ß inhibition/knockdown did not ameliorate the proliferation defect in MFS-VSMCs but improved MFS-VSMC proteolysis and apoptosis and partially rescued fibrillin-1 deposition. To conclude, we have identified GSK3ß as a novel target for MFS, forming the foundation for future work in MFS and other aortic diseases.

Spectrum of mutations in USH2A in British patients with Usher syndrome type II.

Usher syndrome (USH) is a combination of a progressive pigmentary retinopathy, indistinguishable from retinitis pigmentosa, and some degree of sensorineural hearing loss. USH can be subdivided in Usher type I (USHI), type II (USHII) and type III (USHIII), all of which are inherited as autosomal recessive traits. The three subtypes are genetically heterogeneous, with six loci so far identified for USHI, three for USHII and only one for USHIII. Mutations in a novel gene, USH2A, encoding the protein usherin, have recently been shown to be associated with USHII. The gene encodes a protein with partial sequence homology to both laminin epidermal growth factor and fibronectin motifs. We analysed 35 British and one Pakistani Usher type II families with at least one affected member, for sequence changes in the 20 translated exons of the USH2A gene, using heteroduplex analysis and sequencing. Probable disease-causing mutations in USH2A were identified in 15 of 36 (41.7%) Usher II families. The most frequently encountered mutation (11/15 families or 11/18 mutated alleles) was del2299G in exon 13, resulting in a frameshift and premature stop codon. Other mutations include insertions and point mutations, of which two are previously unreported. Five different polymorphisms were also detected. Our results indicate that mutations in this gene are responsible for disease in a large proportion of British Usher type II patients. Moreover, if screening for mutations in USH2A is considered, it is sensible to screen for the del2299G mutation first.