Retinitis punctata albescens associated with the Arg135Trp mutation in the rhodopsin gene

PURPOSE

To screen for mutations in the rhodopsin, peripherin/RDS, and ROM1 genes in a family affected with retinitis punctata albescens. Because clinical heterogeneity was observed in this family, with some members affected with retinitis punctata albescens and one member affected with features typical of retinitis pigmentosa, we analyzed the apolipoprotein E gene to elucidate this unusual intrafamilial heterogeneity.

METHODS

The coding sequences of these genes were analyzed with a combination of single-strand conformation polymorphism and direct sequence analysis. Haplotypes of the apolipoprotein E gene were analyzed by polymerase chain reaction and enzymatic digestion.

RESULTS

The Arg135Trp mutation in the rhodopsin gene was observed in all affected members of this family, but no mutation was detected in the peripherin/RDS or ROM1 genes. The e4 allele of the apolipoprotein E gene apparently cosegregated with the albescens phenotype in this family.

CONCLUSIONS

The albescent phenotype in retinal dystrophy appears to not be caused exclusively by a peripherin/RDS gene mutation, and we suggest that the apolipoprotein E gene may play a role in the albescent phenotype.

Evidence for a fourth locus in Usher syndrome type I

Usher syndrome type I (US1) is an autosomal recessive condition in which three different genes have been already localised (USH1A, USH1B, and USH1C on chromosomes 14q32, 11q13, and 11p15 respectively). The genetic heterogeneity of US1 has been confirmed in a previous study by linkage analysis of 20 French pedigrees. Here, we report the genetic exclusion of the three previously reported loci in two large multiplex families of Moroccan and Pakistani origin, suggesting the existence of at least a fourth locus in Usher syndrome type I.

No evidence of genetic heterogeneity in dominant optic atrophy

Autosomal dominant optic atrophy (OPA, MIM 165500) is an eye disease causing a variable reduction of visual acuity with an insidious onset in the first six years of life. It is associated with a central scotoma and an acquired blue-yellow dyschromatopsia. A gene for dominant optic atrophy (OPA1) has recently been mapped to chromosome 3q in three large Danish pedigrees. Here, we confirm the mapping of OPA1 to chromosome 3q28-qter by showing close linkage of the disease locus to three recently reported microsatellite DNA markers in the interval defined by loci D3S1314 and D3S1265 in four French families (Zmax = 5.13 at theta = 0 for probe AFM 308yf1 at locus D3S1601). Multipoint analysis supports the mapping of the disease gene to the genetic interval defined by loci D3S1314 and D3S1265. The present study provides three new markers closely linked to the disease gene for future genetic studies in OPA.

Nicotine-induced exocytotic norepinephrine release in guinea-pig heart, human atrium and bovine adrenal chromaffin cells: modulation by single components of ischaemia

The influence of single components of myocardial ischaemia, such as anoxia, substrate withdrawal, hyperkalemia and extracellular acidosis, on nicotine-induced norepinephrine (NE) release was investigated in the isolated perfused guinea-pig heart, in incubated human atrial tissue and in cultured bovine adrenal chromaffin cells (BCC). In normoxia, nicotine (1-1000 mumol/l) evoked a concentration-dependent release of NE (determined by high pressure liquid chromatography and electrochemical detection) from guinea-pig heart and human atrium. In contrast to selective anoxia (Po2 < 5 mmHg) or glucose withdrawal, respectively, anoxia in combination with glucose withdrawal (5-40 min) markedly potentiated nicotine-induced NE release both in guinea-pig heart and human atrium. The sensitization of cardiac sympathetic nerve endings to nicotine was characterized by a lower threshold concentration and an approximate two-fold increase of maximum NE release, peaking after 10 min of anoxia and glucose withdrawal. Cyanide intoxication (1 mmol/l) combined with glucose withdrawal resulted in a similar increase of nicotine-induced sympathetic transmitter release both in guinea-pig heart and human atrium. In contrast, the nicotine-induced (10 mumol/l) NE overflow was only slightly potentiated by 10 min of global ischaemia in guinea-pig heart. Both hyperkalemia ([K+] 16 mmol/l) and acidosis (pH 6.8-6.0) distinctly attenuated the stimulatory effect of nicotine in guinea-pig heart and human atrium under normoxic conditions. Consistent with an exocytotic release mechanism, NE release was dependent on the presence of extracellular calcium under all conditions tested. Furthermore, NE overflow from guinea-pig heart was accompanied by a release of the exocytosis marker neuropeptide Y (NPY; determined by radioimmunoassay). In BCC, nicotine (1-10 mumol/l) evoked a release of NE and NPY and a transient rise of [Ca2+]i (determined with fura-2) during normoxia which were both dependent on the presence of extracellular calcium. Both hyperkalemia and acidosis markedly reduced the exocytotic release of sympathetic transmitters and the corresponding [Ca2+]i-transients. These data demonstrate that nicotine-induced cardiac exocytotic NE release is markedly potentiated during short-term anoxia in combination with glucose withdrawal. In contrast, a brief period of ischaemia causes only a slight sensitization of cardiac sympathetic nerve endings to nicotine. This discrepancy may be due to an attentuation of nicotine-evoked NE release by hyperkalemia and by acidosis. The protective effect of these factors against anoxia-induced sensitization to nicotine appears to be related to the inhibition of nicotine-evoked [Ca2+]i-transients.

A gene for Leber's congenital amaurosis maps to chromosome 17p

Leber's congenital amaurosis (LCA) is an autosomal recessive disease responsible for congenital blindness. It is the most early and severe form of inherited retinopathy and accounts for 5% of all inherited retinal dystrophies. Here we report the first mapping of a gene for LCA to the distal short arm of chromosome 17 by linkage analysis in 15 multiplex families (Zmax = 5.14 at theta = 0.15 for probe AFM070xg5 at the D17S1353 locus). When our sample was split into two groups according to the ethnic origin of the patients we were able to confirm the presence of a gene for LCA on chromosome 17p by both homozygosity mapping and linkage analysis in five families of Maghrebian origin (LCA1, Zmax = 7.21 at theta = 0.01 at the D17S1353 locus), while negative results were found in 10 families of French ancestry. Haplotype analyses supported the placement of LCA1 between loci D17S796 and D17S786 (maximum likelihood estimate for location of the disease gene over the D17S1353 locus). The genetic heterogeneity of LCA will complicate the prenatal detection of this frequent cause of congenital blindness.

Exclusion of the cone-specific alpha-subunit of the transducin gene in Stargardt's disease

Stargardt's disease is an autosomal recessive infantile macular degeneration of unknown origin whose gene has been recently mapped to chromosome 1p21-p13 by linkage analysis in eight multiplex families. Since the cone-specific alpha-subunit of the transducin gene (GNAT2) has been mapped to chromosome 1p13, we tested GNAT2 as the disease-causing gene in our series. Using a novel intragenic polymorphism, we show here that GNAT2 is most probably located centromeric to the genetic interval encompassing the disease gene (D1S424-D1S236, location score = 3.54). In addition, single-strand conformation polymorphism and sequence analyses of the eight exons of the GNAT2 gene was performed in our probands. No evidence of a deleterious base substitution was observed in any affected individual. Taken together, these results support the exclusion of GNAT2 as the causal disease gene of Stargardt's disease. come. The pathogenesis is unknown and the treatment is limited to ultraviolet ray protection with dark glasses. Stargardt's disease has been recently mapped to chromosome 1p21-p13 in the genetic interval defined by loci D1S424 and D1S236. In addition, our previous study has suggested that Stargardt's disease is genetically homogeneous (Kaplan et al. 1993). With respect to the physical mapping of the proteins specific to the retinal pigmentary epithelium or to cones we noted that the cone-specific alpha-subunit of the transducin gene (GNAT2) has been mapped to chromosome 1p13 (Wilkie et al. 1992). The human GNAT2 is 9967 bp in length and consists of eight exons with seven introns (Morris and Fong 1993). In the present study, we examined this gene as the candidate gene in eighteen unrelated patients affected with Stargardt's disease.

A gene for late-onset fundus flavimaculatus with macular dystrophy maps to chromosome 1p13

Fundus flavimaculatus with macular dystrophy is an autosomal recessive disease responsible for a progressive loss of visual acuity in adulthood, with pigmentary changes of the macula, perimacular flecks, and atrophy of the retinal pigmentary epithelium. Since this condition shares several clinical features with Stargardt disease, which has been mapped to chromosome 1p21-p13, we tested the disease for linkage to chromosome 1p. We report here the mapping of the disease locus to chromosome 1p13-p21, in the genetic interval defined by loci D1S435 and D1S415, in four multiplex families (maximum lod score 4.79 at recombination fraction 0 for probe AFM217zb2 at locus D1S435). Thus, despite differences in the age at onset, clinical course, and severity, fundus flavimaculatus with macular dystrophy and Stargardt disease are probably allelic disorders. This result supports the view that allelic mutations produce a continuum of macular dystrophies, with onset in early childhood to late adulthood.

Telepathology: frozen section diagnosis at a distance

Telepathology may be used to provide a frozen section service to hospitals without a department or institute of pathology. We have developed a telepathology system using the commercially available Integrated Services Digital Network (ISDN). The main software and hardware elements of our system are: Apple Macintosh workstations, a program for simultaneous transfer of image, voice and data, and a data bank for storage of patients' data and microscopic images. A picture instrument manager (PIM) makes remote control of microscopes or other instruments possible. The system connects the Department of Pathology of the University of Basel with the Regional Hospital of Samedan, 250 km away, and the Regional Hospital of Burgdorf, 100 km away. During a period of 20 months, frozen sections with the hospitals in Samedan and Burgdorf were performed in 53 patients. Between 54 and 58 s were required for the transfer of a diagnostic 8-bit grey level image containing 341 +/- 26.1 (standard error) kbytes (n = 13) or a diagnostic 24-bit colour image containing 165 +/- 16.9 kbytes (n = 40). Frozen section diagnosis was completed in 20-40 min. True-positive diagnoses of malignant tumours were achieved in 85.7% of cases (sensitivity = 0.857). No false-positive diagnosis was made. In 3 of the 53 cases telepathological diagnosis was not possible for technical reasons.

Intercomparison of spectral-UV-radiation measurement systems

The results of what is to our knowledge the first intercomparison of seven independent spectroradiometers measuring solar UV irradiances are presented. The intercomparison was carried out in the GSF-Forschungszentrum für Umwelt und Gesundheit, Neuherberg (near Munich, Germany), on 13 July 1990. The spectroradiometric measurements were supplemented by other meteorological, optical, and chemical measurements at the same time. As this day was cloudless, the data can be compared with the measurements taken by Bener in Switzerland in the 1960's and with the results of radiative transfer models. The measured irradiances at noon differed by factors of up to 100. These large differences demonstrate the great difficulties with this type of measurement. Some instrument systems, however, ranged within tolerances of ±10%, thus allowing us to make recommendations for the spectroradiometry of solar UV irradiances.

Use of Norplant implants in a New York City clinic population

Two-hundred-eight women attending family planning clinics in New York City who received the Norplant contraceptive system during the first sixteen months of Norplant implants insertions were evaluated. Within this clinic population, Norplant implants were a popular contraceptive choice and were removed from 64 of the 208 recipients. Reasons for removal included bleeding, weight gain, and headache, and were consistent with those found in the clinical trials. Prior satisfaction with oral contraceptives did not predict success or failure with Norplant implants. The rate of follow-up visits to the family planning clinics was low. However, evidence exists that these women did not lose contact with the medical center and continued to receive health care.

Estimation and test for linkage between markers: a comparison of lod score and χ (2) test in a linkage study of maritime pine (Pinus pinaster Ait.)

The first step in the construction of a linkage map involves the estimation and test for linkage between all possible pairs of markers. The lod score method is used in many linkage studies for the latter purpose. In contrast with classical statistical tests, this method does not rely on the choice of a first-type error level. We thus provide a comparison between the lod score and a χ (2) test on linkage data from a gymnosperm, the maritime pine. The lod score appears to be a very conservative test with the usual thresholds. Its severity depends on the type of data used.

An estimation of the genome length of maritime pine (Pinus pinaster Ait.)

The genome length, in units of Morgans or centimorgans, is a fundamental feature of a species. It can be calculated from a complete linkage map. However, the genome size can be estimated with partial linkage data. Using linkage data obtained by the analysis of a two-dimensional electrophoresis of the proteins contained in an haploid organ, the megagametophyte, we suggest an estimation and a confidence interval of the genome length of a gymnosperm, the maritime pine (Pinus pinaster Ait.). The results indicate an important gap between the physical and the genetic maps.

Genetic heterogeneity of Usher syndrome type 1 in French families

Usher syndrome type 1 (US1) is an autosomal recessive disease characterized by profound congenital hearing impairment with unintelligible speech, early retinitis pigmentosa, and constant vestibular dysfunction. Three localizations have been described in US1: USH1A, 14q32; USH1B, 11q13.5; and USH1C, 11p15. Studying a series of 33 affected individuals belonging to 20 US1 pedigrees of French ancestry, we found that none of the three localizations accounted for all US1 families in our series (Zmax = 1.48 at theta = 0.10; Zmax = 1.45 at theta = 0.10; and Zmax = 0.36 at theta = 0.20 for probes MLJ14, Zd5, and Mfd58, respectively, at loci D14S13, D11S527, and D11S419, respectively). However, when our sample was split into two groups according to the geographic origin of the probands' grandparents, we were able to confirm the presence of a gene for US1 on chromosome 14q32 (USH1A) in 9 families originating from the Poitou region in Western France (Department of Deux-Sèvres; Zmax = 4.46 at theta = 0 for probe MLJ14 at the D14S13 locus, Morton likelihood ratio test, P < 0.01). Moreover, we refined the genetic mapping of USH1A by showing that the disease gene maps to the D14S13 locus, within the genetic interval defined by loci D14S78 and D14S250 (location score in log base 10 = 4.90). Consistent with this, nonsignificant lod score values for linkage to either USH1B or USH1C were found in this group.(ABSTRACT TRUNCATED AT 250 WORDS)

Complete spontaneous thrombosis of a giant intracranial aneurysm

In a 23-year-old woman CT demonstrated a patent giant intracranial aneurysm. MRI, CT and angiography one month later demonstrated complete spontaneous thrombosis of the aneurysm. The diagnosis was confirmed surgically and pathologically. This case demonstrates that a normal angiogram can be associated with a thrombosed giant aneurysm, and that this diagnosis should be considered in cases of angiographically-occult cerebral vascular malformations.

Stargardt's disease is not allelic to the genes for neuronal ceroid lipofuscinoses

Stargardt's disease is an autosomal recessive condition characterised by a rapid and bilateral loss of central vision at around 7 to 12 years, with typical changes in the macular and perimacular region. It is one of the most frequent causes of macular degeneration in childhood and accounts for 7% of all retinal dystrophies. Considering that inclusions of lipofuscin-like substances are observed in retinal pigmentary cells of patients with Stargardt's disease on the one hand, and that the early symptoms of neuronal ceroid lipofuscinosis (CLN3) are suggestive of Stargardt's disease on the other hand (age of loss of visual acuity, appearance of the fundus), we decided to test allelism of Stargardt's disease with the infantile (CLN1) and juvenile forms of neuronal ceroid lipofuscinosis (CLN3), which map to chromosomes 1p32 and 16p12-p11 respectively. Using highly informative microsatellite DNA markers in eight multiplex families, we were able to exclude Stargardt's disease from the vicinity of the CLN1 and CLN3 loci. These results strongly reject the hypothesis of allelism of Stargardt's disease with the neuronal forms of ceroid lipofuscinosis.

A gene for Stargardt's disease (fundus flavimaculatus) maps to the short arm of chromosome 1

Stargardt's disease (fundus flavimaculatus) is one of the most frequent causes of macular degeneration in childhood and accounts for 7% of all retinal dystrophies. It is an autosomal recessive condition characterized by a bilateral loss of central vision occurring at age 7-12 years. Genetic linkage analysis of eight families has assigned the disease locus to chromosome 1p21-p13. Multipoint linkage analysis and haplotype analysis has allowed us to establish the best estimate for location of the gene over the locus D1S435 (maximum lod score of 12.66). Our results are consistent with the genetic homogeneity of this condition.

Telepathology with an integrated services digital network--a new tool for image transfer in surgical pathology: a preliminary report

We describe a low-cost telepathology system working via a commercial integrated services digital network (ISDN) and consisting of modular software and hardware elements. The main elements are Apple Macintosh workstations; a software program for the simultaneous transfer of pictures, voice, and data; and procedures for image processing and general administration of all the information generated. Additionally, the system allows remote control of any peripheral instruments by a "picture-instrument manager." The transfer rate is currently 64 kbit/s; it will be extended to 128 kbit/s (ISDN basic rate) in the near future and to 2 Mbit/s (ISDN primary rate) in the next 2 years. The system was tested by the regional hospital in Samedan, Switzerland, and the Department of Pathology, University of Basel, Basel, Switzerland, a distance of 250 km, by offering a remote frozen section service to the regional hospital in 16 cases. Fifty-four to 58 seconds were needed for the transfer of a diagnostic 8-bit grey-level image containing 341 (median value) +/- 26.1 (standard error) kbytes (n = 13) or a diagnostic 24-bit color image containing 165 (median value) +/- 16.9 (standard error) kbytes (n = 3). The time required for a diagnostic session was between 25 and 35 minutes.