Abnormal crossing of the optic fibres shown by evoked magnetic fields in patients with ocular albinism with a novel mutation in the OA1 gene.

AIM: To perform genealogical and clinical studies in Finnish families with X linked ocular albinism (OA1), including characterisation of the potential misrouting of optic fibres by evaluating visual evoked magnetic fields (VEFs), and to determine the mutation behind the disease. METHODS: Three families with OA1 were clinically examined. VEFs were measured in two affected males and in one female carrier to characterise the cortical activation pattern after monocular visual stimulation. The neuronal sources of the VEFs were modelled with equivalent current dipoles (ECDs) in a spherical head model. All coding exons of the OA1 gene were screened for mutations by single strand conformation analysis and direct polymerase chain reaction sequencing. RESULTS: Genealogical studies revealed that the three families were all related. The affected males had foveal hypoplasia with reduced visual acuity varying from 20/200 to 20/50, variable nystagmus, iris transillumination, and hypopigmentation of the retinal pigment epithelium. The ECD locations corresponding to the VEFs revealed abnormal crossing of the optic fibres in both affected males, but not in the carrier female. A novel point mutation, leading to a STOP codon, was identified in the fifth exon of the OA1 gene. CONCLUSIONS: The data indicate that the novel mutation 640C>T in the OA1 gene is the primary cause of the eye disease in the family studied. VEFs with ECD analysis was successfully used to demonstrate abnormal crossing of the optic fibres.

Phylogenetic relationships among higher Nemertean (Nemertea) Taxa inferred from 18S rDNA sequences.

We estimated the phylogenetic relationships of 15 nemertean (phylum Nemertea) species from the four subclasses Hoplo-, Hetero-, Palaeo-, and Bdellonemertea with 18S rDNA sequence data. Three outgroup taxa were used for rooting: Annelida, Platyhelminthes, and Mollusca. Parsimony and maximum-likelihood analyses supported the monophyletic status of the Heteronemertea and a taxon consisting of hoplonemerteans and Bdellonemertea, while indicating that Palaeonemertea is paraphyletic. The monophyletic status of the two nemertean classes Anopla and Enopla is not supported by the data. The unambiguous clades are well supported, as assessed by a randomization test (bootstrapping) and branch support values.

Autosomal recessive cornea plana. A clinical and genetic study of 78 cases in Finland.

PURPOSE: To review the literature of autosomal recessive cornea plana (RCP) and to perform a clinical and genetic study on this disorder in Finland. The 78 Finnish RCP patients represent the majority of RCP cases worldwide; outside Finland only 35 cases have been reported. METHODS: Families with RCP, particularly in northern Finland, have been followed up by the senior author since the 1950s and extensive genealogical studies have been made. RESULTS: The most typical symptoms are greatly reduced corneal refraction, 25-35 dioptres, causing strong hyperopia, slight microcornea, an extended limbus zone, a central, deep corneal opacity and a marked arcus senilis, seen even before the age of 20. We present a pedigree comprising 33 affected persons with cornea plana. We have mapped the two genes for the dominantly and the recessively inherited type of cornea plana to the same region on the long arm of chromosome 12, (12q21). CONCLUSIONS: In northern Finland RCP has a higher frequency than elsewhere, probably as a result of a strong founder effect in the population that arrived in these regions approx. 400 years ago. The strong accumulation of this rare disease in these isolated areas and the strong genealogical connections between different families with RCP, suggest that probably all the Finnish RCP cases are caused by the same mutation.

Autosomal dominant cornea plana: clinical findings in a Cuban family and a review of the literature.

Cornea plana may occur in connection with malformations of the eye or of other parts of the body. As an isolated ocular anomaly, it may be inherited in an autosomal recessive or in an autosomal dominant fashion. We have previously mapped genes for both forms of the disease to 12q21. We studied 36 members of three generations of a Black Cuban family with autosomal dominant cornea plana. Three affected males and 11 affected females were examined. Corneal refraction varied between 37.50 and 42.75 diopters. Horizontal corneal diameter ranged from 8.75 to 11.25 mm. The cornea was clear and the limbal zone only occasionally widened. A marked arcus senilis was present in six patients aged 30 to 58 years, but in none of their healthy relatives. The anterior chamber was shallow in those affected, varying in depth from 1.68 to 2.38 mm. One woman was blind from closed-angle glaucoma. The axial length was within normal limits in all patients.