Mutation update: TGFBI pathogenic and likely pathogenic variants in corneal dystrophies.

Human transforming growth factor β-induced (TGFBI), is a gene responsible for various corneal dystrophies. TGFBI produces a protein called TGFBI, which is involved in cell adhesion and serves as a recognition sequence for integrins. An alteration in cell surface interactions could be the underlying cause for the progressive accumulation of extracellular deposits in different layers of the cornea with the resulting changes of refractive index and transparency. To this date, 69 different pathogenic or likely pathogenic variants in TGFBI have been identified in a heterozygous or homozygous state in various corneal dystrophies, including a novel variant reported here. All disease-associated variants were inherited as autosomal-dominant traits but one; this latter was inherited as an autosomal recessive trait. Most corneal dystrophy-associated variants are located at amino acids Arg124 and Arg555. To keep the list of corneal dystrophy-associated variant current, we generated a locus-specific database for TGFBI (http://databases.lovd.nl/shared/variants/TGFBI) containing all pathogenic and likely pathogenic variants reported so far. Non-disease-associated variants are described in specific databases, like gnomAD and ExAC but are not listed here. This article presents the most recent up-to-date list of disease-associated variants

Split hand malformation, hypospadias, microphthalmia, distinctive face and short stature in two brothers suggest a new syndrome

Split hand/foot malformation (SHFM) is a genetically heterogeneous limb malformation that may be isolated or associated with other malformations. More than 50 recognizable entities with SHFM have been described and at least 5 mapped genetic loci have been implicated. Two brothers with intrauterine growth retardation, short stature, distinctive face, microphthalmia, genital anomalies, and SHFM are described. Molecular analyses of TP63, HOXA13, and HOXD13 genes were normal. We propose this pattern to be a newly recognized SHFM syndrome. � 2005 Wiley-Liss, Inc

Gene therapy for retinitis pigmentosa caused by MFRP mutations: human phenotype and preliminary proof of concept

Autosomal recessive retinitis pigmentosa (RP), a heterogeneous group of degenerations of the retina, can be due to mutations in the MFRP (membrane-type frizzled-related protein) gene. A patient with RP with MFRP mutations, one of which is novel and the first splice site mutation reported, was characterized by noninvasive retinal and visual studies. The phenotype, albeit complex, suggested that this retinal degeneration may be a candidate for gene-based therapy. Proof-of-concept studies were performed in the rd6 Mfrp mutant mouse model. The fast-acting tyrosine-capsid mutant AAV8 (Y733F) vector containing the small chicken β-actin promoter driving the wild-type mouse Mfrp gene was used. Subretinal vector delivery on postnatal day 14 prevented retinal degeneration. Treatment rescued rod and cone photoreceptors, as assessed by electroretinography and retinal histology at 2 months of age. This AAV-mediated gene delivery also resulted in robust MFRP expression predominantly in its normal location within the retinal pigment epithelium apical membrane and its microvilli. The clinical features of MFRP-RP and our preliminary data indicating a response to gene therapy in the rd6 mouse suggest that this form of RP is a potential target for gene-based therapy

Genotype-phenotype correlations in Chinese patients with TGFBI gene-linked corneal dystrophy*

In this paper, we report the clinical and molecular features of the distinct TGFBI (human transforming growth factor β-induced, OMIM No. 601692) gene-linked corneal dystrophy. Altogether, five pedigrees and ten unrelated individuals diagnosed as corneal dystrophy were recruited. Peripheral venous DNA was extracted, and then amplified by polymerase chain reaction (PCR) and scanned for mutation by single-stranded conformation polymorphism (SSCP). Direct DNA sequencing was used to analyze the mutations of the TGFBI gene. In our study, thirty patients from five pedigrees and ten sporadic patients were diagnosed as four TGFBI gene-linked corneal dystrophies of granular corneal dystrophy type I (GGCD I), Avellino corneal dystrophy (ACD), lattice corneal dystrophy type I (LCD I), and lattice corneal dystrophy type IIIA (LCD IIIA), and in total, seven disease-causing mutations, namely R555W, A546D, A546T, and T538P mutations in exon 12, R124H and R124C mutations in exon 4, and P501T mutation in exon 11, were identified, while four polymorphisms of V327V, L472L, F540F, and 1665–1666insC were screened in exons 8, 11, and 12. The study ascertained the tight genotype-phenotype relationship and confirmed the clinical and genetic features of four TGFBI gene-linked corneal dystrophies