Accumulation patterns of endogenous β-aminobutyric acid during plant development and defence in Arabidopsis thaliana

We recently discovered that β-aminobutyric acid (BABA), a molecule known for its ability to prime defences in plants, is a natural plant metabolite. However, the role played by endogenous BABA in plants is currently unknown. In this study we investigated the systemic accumulation of BABA during pathogen infection, levels of BABA during plant growth and development and analysed mutants possibly involved in BABA transport or regulation. BABA was quantified by LC-MS using an improved method adapted from a previously published protocol. Systemic accumulation of BABA was determined by analysing non-infected leaves and roots after localised infections with Plectosphaerella cucumerina or Pseudomonas syringae pv. tomato (Pst) DC3000 avrRpt2. The levels of BABA were also quantified in different plant tissues and organs during normal plant growth, and in leaves during senescence. Mutants affecting amino acid transport (aap6, aap3, prot1 and gat1), γ-aminobutyric acid levels (pop2) and senescence/defence (cpr5-2) were analysed. BABA was found to accumulate only locally after bacterial or fungal infection, with no detectable increase in non-infected systemic plant parts. In leaves, BABA content increased during natural and induced senescence. Reproductive organs had the highest levels of BABA, and the mutant cpr5-2 produced constitutively high levels of BABA. Synthetic BABA is highly mobile in the receiving plant, whereas endogenous BABA appears to be produced and accumulated locally in a tissue-specific way. We discuss a possible role for BABA in age-related resistance and propose a comprehensive model for endogenous and synthetic BABA.

[New strategies in pediatric ophthalmic oncology]

Retinoblastoma represents 11% of all cancers during the first year of life. New drugs and focal treatments have been developed in order to avoid the side effects of systemic chemotherapy and external radiotherapy. New targeted and local administration strategies such as periocular chemotherapy (topotecan) or direct ophthalmic artery delivery (carboplatin), are already used today in selected resistant cases. Radiotherapy, presently indicated only as a second-line treatment, is also subject to new techniques, targeting tumors more closely to avoid involving healthy tissue and reduce the risk of radio-induced nonocular tumors. Stereotactic conformal radiotherapy and proton therapy may thus be included in the new range of treatment methods in retinoblastoma.

Diagnosis and current management of retinoblastoma

Retinoblastoma represents the prototypic model for inherited cancers. The RB1 gene was the first tumor suppressor gene to be identified. It represents the most frequent primary eye cancer in children under 15 years old, habitually occurring in infancy, even in utero, but can be observed in older children or young adults. Many other retinal lesions may also simulate retinoblastoma. The two major presenting signs are leukocoria and strabismus, but other ocular or general signs may be observed. A highly malignant tumor, retinoblastoma can nowadays be cured. The heritable form, however, carries a high risk of second nonocular tumors. Treatment in the early stages of disease holds a good prognosis for survival and salvage of visual function. In very late stages, however, the prognosis for ocular function and even survival is jeopardized.

[Centenary of the first radiotherapy treatment of retinoblastoma (Hilgartner, 1903)]

One hundred years ago, Hilgartner used external radiotherapy for the first time in the treatment of retinoblastoma. This first case was published in the Texas Medical Journal in 1903. Immediate results were reported to be excellent but the long-term outcome was not known. The first documented cure of retinoblastoma over a long period of time was a case initially treated by Verhoeff (Boston) in 1917, with histopathological findings provided 71 years later by Marcus et al. at the patient's death. Henry Louis Hilgartner was born in 1868 in Baltimore and died in 1937 at the age of 69. His revolutionary treatment developed from the discovery of X-rays in 1895 by Wilhelm Conrad Röntgen and the parallel discovery of radioactivity by Henri Bequerel and Marie and Pierre Curie. In the sociopolitical context of 1903, Emile Loubet was president of France and this same year saw the Wright brothers' first motorized flight with the first power-driven heavier-than-air machine. The development of radiotherapy in the treatment of retinoblastoma can be divided into three distinct periods: an initial period of trial and error lasting from 1903 to 1928; a second period from 1929 to 1948 covering the introduction of calibrated radon needles up to the advent of external radiotherapy, and a third period, from 1948 to the present day, which can be considered a time of technical improvement and innovation. One hundred years ago, radiotherapy made a triumphant entry on the scene of retinoblastoma management. With our present knowledge of its side effects, we are now trying to remove it.

Pulverulent cataract with variably associated microcornea and iris coloboma in a MAF mutation family

AIMS

To report the detailed clinical findings in a three generation pedigree with autosomal dominant cataract, microcornea, and coloboma resulting from mutation of the lens development gene, MAF.

METHODS

Five members of a three generation pedigree with progressive cataracts underwent detailed ophthalmic examination to characterise associated ocular phenotypic features.

RESULTS

The cataracts present in all affected individuals were cortical, and/or nuclear, pulverulent opacities. Corneal diameters of 10-10.25 mm were present in two family members. Axial lengths were in the normal range. Bilateral iris coloboma in the 6 o'clock position was present in one patient. Uveal melanoma was present in one patient, with uveal naevi in this and one other patient.

CONCLUSION

The bZIP transcription factor MAF is a key lens development gene that regulates the expression of the crystallins. Individuals with a mutation in MAF may have pulverulent cataract alone or cataract in association with microcornea or iris coloboma.

[New strategies in the management of retinoblastoma]

It was rare that a child survived retinoblastoma at the beginning of the twentieth century. Today the survival rate is in the order of 95% in reference centers, with new strategies improving prognosis step by step. Systematic enucleation used to be the starting point of any true and structured management, until the advent of radiotherapy made it possible not only to save lives but also to retain some useful vision. Early diagnosis has enabled focal therapies such as photocoagulation, cryocoagulation, and radioactive applicators to open up a new era of targeted tumor treatment. However, the onset of nonocular tumors secondary to radiotherapy, the resistance of certain tumors to irradiation, and unsightly cosmetic consequences all justify research into alternative therapeutic strategies. New types of chemotherapy have shown spectacular results and are currently under study: chemoreduction to make large tumors more manageable and enable less aggressive treatment of tumors located in delicate sites, thermochemotherapy using the effect of heat on plasma membrane permeability to antimitotics, and chemotherapy associated with cyclosporine to reduce the multidrug resistance of certain tumors. The aim is to avoid primary enucleation and external beam radiation as far as possible. The future may lie in local chemotherapy, hyperthermia, and dynamic phototherapy, accelerated proton beam radiotherapy also has promising prospects.

[Diagnosis and treatment of intraocular tumors in the child]

PURPOSE

To remind of the absolute necessity for early diagnosis in the presence of ocular signs in children giving rise to possible intraocular tumours.

METHOD

Based on our own experience of intraocular tumours in children, together with findings from the literature, diagnostic criteria and methods of treatment are presented.

RESULTS

Retinoblastoma is the predominant cause of intraocular tumours in children, representing over 80% of cases under the age of 15 years. Other diseases may give rise to the same initial signs, usually leukocoria, sometimes strabismus, more rarely other atypical signs. Elements taken into account for diagnosis include age, sex, laterality, heredity, size of the globe, clinical aspect of the tumours, presence of calcifications and vitreous seeding. Full fundus examination under general anaesthetic is usually necessary. Biological examination, ultrasonography, computerized tomography and MRI enable an accurate diagnosis to be made in the majority of doubtful cases. The management of retinoblastoma is adapted for each individual case from the wide range of treatments available. Enucleation, radioactive applicators (...), brachytherapy (...), cryo- and photocoagulation represent classical measures. Primary chemotherapy, combined with other treatments such as thermotherapy, has become the treatment of choice in those cases where external beam radiotherapy has been used up to now, or in some instances before enucleation. Enucleation is usually carried out for medullo-epitheliomas, but brachytherapy may offer an alternative.

CONCLUSION

Any unexplained ocular sign in children should be considered as a possible retinoblastoma, making an accurate and certain diagnosis imperative. Early treatment may save not only the life but also the vision of patients carrying this highly malignant lesion.

Further delineation of the facial 13q14 deletion syndrome in 13 retinoblastoma patients

Thirteen years ago, Motegi and colleagues (J Med Genet 1987;24:696-697) summarized the specific facial phenotype of six Japanese retinoblastoma patients with interstitial 13q14 deletions. Among a series of 228 propositi with retinoblastoma referred to the Lausanne Retinoblastoma Clinic for treatment and genetic counseling between 1986 and 1997, 13 (5.7%) were diagnosed with a cytogenetic de-novo 13q14 deletion. We confirm the presence of the reported facial phenotype in our population of Caucasian patients and describe additional clinical traits, thus extending the facial phenotype associated with the 13q14 deletion. Del(13q14) comprises, among others, cranial anomalies, frontal bossing, deeply grooved and long philtrum, depressed and broad nasal bridge, bulbous tip of the nose, thick lower lip, thin upper lip, broad cheeks, and large ears and lobules. Recognition of this particular facial appearance was instrumental in the genetic diagnosis of 13q deletions and in the presymptomatic diagnosis of retinoblastoma in a significant number of our cases. Identification of this phenotype in a retinoblastoma patient allows for efficient diagnosis of recurrence in his progeny and/or sibship, while its ignorance will compromise genetic counseling due to the possible difficulties in detecting large deletions by standard molecular mutation analysis. Recognition of this syndrome in newborns without known familial risk for retinoblastoma is even more important as it is a clear warning sign that indicates immediate ophthalmic examination.

A progressive autosomal recessive cataract locus maps to chromosome 9q13-q22

Cataracts are the leading cause of blindness in most countries. Although most hereditary cases appear to follow an autosomal dominant pattern of inheritance, autosomal recessive inheritance has been clearly documented and is probably underrecognized. We studied a large family-from a relatively isolated geographic region-whose members were affected by autosomal recessive adult-onset pulverulent cataracts. We mapped the disease locus to a 14-cM interval at a novel disease locus, 9q13-q22 (between markers D9S1123 and D9S257), with a LOD score of 4.7. The study of this progressive and age-related cataract phenotype may provide insight into the cause of the more common sporadic form of age-related cataracts.

First-line chemotherapy with local treatment can prevent external-beam irradiation and enucleation in low-stage intraocular retinoblastoma

PURPOSE

To evaluate the efficacy of first-line chemotherapy (CT) in preventing external-beam radiotherapy (EBR) and/or enucleation in patients with retinoblastoma (Rbl).

PATIENTS AND METHODS

Twenty-four patients with newly diagnosed unilateral or bilateral Rbl received CT associated with local treatment (LT). Two to five courses of etoposide and carboplatin were administered at 3- to 4-week intervals, depending on tumor response, and were completed each time by LT.

RESULTS

Tumor response was observed in all eyes. Twenty-one of 24 patients showed a complete response (CR) that persisted at a median follow-up (FU) of 31 months (range, 4 to 41 months). Among the three patients who relapsed, two were lost to FU and one died of progressive disease. CR was achieved by CT and LT alone in 15 (71.4%) of 21 patients with less advanced disease (groups I to III). Six other patients with advanced disease (groups IV and V) experienced treatment failure and needed salvage treatment by EBR and/or enucleation. The difference between the two patient groups with regard to disease stage was statistically significant (P <.0001). EBR could be avoided in 13 (68.4%) of 19 patients, who presented with groups I to III (15 eyes) and group V (one eye) disease, whereas enucleation could be avoided in only two (40%) of five.

CONCLUSION

CT combined with intensive LT is effective in patients with groups I to III Rbl, permitting the avoidance of EBR in the majority of these young children and, thus, reducing the risk of long-term sequelae. This is in contrast with the disappointing results for patients with groups IV and V Rbl, in whom EBR and/or enucleation was needed.

Rhegmatogenous retinal detachment after treatment of retinoblastoma

PURPOSE

To determine the rate of retinal detachment after treatment of retinoblastoma, to describe the clinical features and management, and to discuss possible pathogenic mechanisms.

METHODS

We retrospectively analyzed the charts of 80 patients (83 eyes) with retinoblastoma treated conservatively between 1963 and 1994, looking specifically for cases that developed a retinal detachment after treatment.

RESULTS

Five patients (5 eyes, stages IVa to Vb) developed a retinal detachment after treatment. Of these, four had undergone external radiotherapy and one had an episcleral cobalt plaque. Retinal detachment developed within three months after radiotherapy and relentlessly progressed in all four eyes over a period of five months to four years. In the eye that received the episcleral cobalt plaque, the detachment remained localized inferiorly. Even though no retinal break could be detected in four eyes, the clinical features were suggestive of a rhegmatogenous detachment: there was retinal thinning adjacent to the regressed tumors, and the evolution was much longer than that of an exudative retinal detachment. A scleral buckling procedure was performed in two eyes and the retina was successfully reattached. The retinal detachment was not operated on in the three other eyes: the hole was too posterior in one eye; retinal surgery was refused in the second eye; and the retinal detachment remained localized inferiorly in the third eye.

CONCLUSION

A retinal detachment developed in 6% of eyes after conservative treatment of retinoblastoma. The possibility of a rhegmatogenous origin should be considered even if no retinal break is detected. In the absence of tumor activity, a scleral buckling repair could be carefully considered if the retinal detachment threatens the macula, and if its evolution is not indicative of an exudative detachment.

[Leukokoria in a child: emergency and challenge]

PURPOSE

To heighten the awareness of the medical world to the importance of correct and rapid diagnosis in the presence of leukocoria in the child.

METHODS

Starting with the presenting symptom, the authors present the guide lines to follow in a practical manner in order to reach a diagnosis in the principal retinal diseases causing leukocoria.

RESULTS

A white pupil is due to retinoblastoma in almost half of all cases. Other possible causes, in order of frequency, are: persistent hyperplastic primary vitreous, Coats' disease, ocular toxocariasis, retinopathy of prematurity, retinal hamartomas. Diagnosis can usually readily be made by ophthalmoscopy, but may be problematic when the clinical presentation is atypical or in the presence of late complications. Age, sex, laterality, heredity, and in particular the presence or absence of calcifications and the size of the globe, are the main criteria for diagnosis. Ultrasonography plays a major role in this essential quest for correct diagnosis, quest which may ultimately lead to enucleation.

CONCLUSION

Leukocoria in the child is a danger signal demanding certain diagnosis within the shortest possible time.

[Diagnostic imaging of intraocular lesions in the child]

BACKGROUND

A certain diagnosis, as soon as possible, is indispensable in children with intraocular lesions, the presence of retinoblastoma always being a possibility.

PATIENTS

From our casuistic of 418 children since 1970 and from the literature, we currently adopt the following attitude. Where the media are clear, a drawing and fundus photographs are made. Echography is performed in all cases. Ultrasound biomicroscopic examination is carried out in all lesions where involvement of the anterior segment is suspected.

RESULTS

Where echography shows no calcifications, computed tomography (CT) is indicated. CT may also enable a possible lesion extension, particularly to the optic nerve, to be studied.

CONCLUSIONS

Magnetic resonance imaging (RMI) is the procedure of choice for evaluating secondary retinal detachment, massive extension of retinoblastoma and for detecting any early involvement of the pineal gland (pinealoblastoma), or any other associated lesion. In case of unilateral unifocal sporadic retinoblastoma, however, no CT or MRI is performed, except where there is a suspected extension into the optic nerve or the orbit. Echography remains the most economical, rapid and safest means of diagnosis even in difficult cases.

[Ocular phenotype in a child with chondrodysplasia punctata, rhizomelic form]

Chondrodysplasia calcificans punctata (CDP) is a rare congenital syndrome characterized by calcific stippling of the hyaline cartilage. CDP is classified into 4 types: the autosomal dominant Conradi-Hünermann type, the autosomal recessive rhizomelic type, the X-linked dominant form and the X-linked recessive form. We present a child affected with a rhizomelic CDP born from consanguinous parents. The ocular phenotype consisted of microphakia associated with a progressive bilateral "cataracta cortico-zonularis suturata". At 11 years of age, a phacoemulsification and intraocular lens implantation was performed in the left eye.

Prognostic factors associated with loss of heterozygosity at the RB1 locus in retinoblastoma

The nature of the tumorigenic mutation was analyzed in 30 retinoblastoma (Rb) tumors (16 non-hereditary and 14 hereditary) and categorized into loss of heterozygosity (LOH) or retention of heterozygosity (non-LOH) at the RB1 locus. These genotypic characteristics were compared with the clinicopathological phenotype for possible correlation. The overall frequency of LOH was roughly 55%, in both hereditary and non-hereditary Rb. The presence of LOH was preferentially associated with differentiated tumors and absence of choroidal invasion. LOH was found in 82% of females versus 33% of males. Finally, LOH-initiated tumors were associated with a significantly younger age at diagnosis in hereditary Rb. In conclusion, the preferential association of LOH with absence of choroidal invasion, tumoral differentiation, and younger age at diagnosis may establish LOH as a prognostic marker in Rb patients.

[Retinoblastoma: clinical and molecular diagnostic aspects]

Retinoblastoma, a tumor of the immature retina concerns babies and young infants in particular. They make up for 14% of malignomas in the first years of life. There are two types of retinoblastoma: In the first two alleles of the gene Rb1 must be inactivated sequentially in the same retinoblast cell until this may escape control. In this case the retinoblastoma is always unilateral and unifocal. This is explained by the lower frequency of two mutations in one retinoblast. The other type, however, is inherited: One allele Rb1 is inactivated in all cells of the organism by mutation. The probability that a second mutation arrives in different retinoblasts is thus high. In this case bilateral multifocal tumors develop. Characterization of the Rb1 gene has permitted identification or at least determination of a haplotype in persons at risk. This knowledge is decisive for early recognition of babies at risk and for genetic counselling.

[Medullo-epithelioma: presentation of 3 cases]

Three cases of medullo-epithelioma are reported from a study of almost 350 cases of retinoblastomas or pseudo-retinoblastomas. The cases concern one female and two male children of 1,5, 2,5 and 6 years of age respectively at the time of diagnosis. Suspected of carrying retinoblastoma, two of the children were enucleated. Histological examination revealed the presence of a benign medullo-epithelioma in one case and a malignant condition in the other. The third case was treated by brachytherapy which led to total destruction of the tumor. A new iridian focus opposite the original tumor appeared one year later and was in turn destroyed by cobalt applicator.

Sex mutation ratio in retinoblastoma and retinoma: relevance to genetic counseling

PURPOSE AND METHOD

The parental origin of initial somatic and germline mutations (M1) in the retinoblastoma gene (RB1) was explored in 36 retinoblastoma (Rb) and 5 retinoma patients, of which 16 were presumably non-hereditary and 25 were hereditary. By this approach the male:female mutation ratio was determined by the gender quotient of mutation origin.

RESULTS

The male to female mutation ratio in hereditary Rb was 19:2, which is consistent with a significant bias towards paternal origin of germline mutation. This ratio was of 5:2 in non-hereditary Rb which is not significant.

DISCUSSION

Together with the published data, these results support a preferential paternal mutagenesis in hereditary Rb, but appear to reject paternal genomic imprinting at the RB1 locus as previously proposed in non-hereditary Rb. Genetic counseling in sporadic Rb may be substantially improved by the identification of the parental origin of initial mutation.

[Uveal effusion syndrome: clinical and ultrastructural aspects]

Spontaneous serous detachment of the choroid and ciliary body, together with bullous serous detachment of the retina (uveal effusion syndrome) is a rare but well-defined syndrome frequently associated with nanophthalmos.

CASE REPORTS

Based on three cases whose one familial, clinical and ultrastructural characteristics of the syndrome are reviewed and the role of ultrasonic biomicroscopy (UBM) presented.

CONCLUSION

The severe and potentially blinding complications encountered after any surgery on these eyes make the recognition of the classical clinical signs and symptoms of the syndrome particularly important. In this context, UBM represents an interesting new tool in terms of diagnosis and pathophysiology understanding.

[Clinical applications of molecular diagnosis of retinoblastoma ain 15 families]

PURPOSE

In 40% retinoblastoma (Rb) results from a hereditary mutation of the Rb susceptibility gene (RB1). In this study, we tested the usefulness of intragenic DNA analysis for ophthalmologic follow-up in affected families.

METHODS

Molecular analysis was performed on 103 DNA samples of 15 Rb families. We used 7 intragenic polymorphic markers and one within the ESD gene for mutation linkage analysis.

FINDINGS

DNA analysis was informative in 88% of relatives at risk of developing Rb. Among them, the presence of a mutated RB1 allele was excluded in 46%, while 29% were unaffected carriers and 25% had inherited the Rb predisposition.

CONCLUSION

In the majority of familial Rb, the DNA analysis allows the identification of children carrying a RB1 mutation and who will need a close ophthalmologic follow-up under general anesthesia. When the mutated gene is absent, ophthalmological examination under narcosis is unnecessary. Finally, identification of asymptomatic carriers improve the accuracy of genetic counselling.

[New retinal tumors in hereditary retinoblastoma]

364 eyes from 230 patients with retinoblastoma diagnosed and treated at the Lausanne University Eye Clinic from 1964 to June 1994 were retrospectively analyzed with respect to the risk of developing new tumour foci following initial therapy. Among them, 119 eyes from 90 hereditary affected patients were included, consisting of 86 bilateral cases and 4 unilateral cases. The mean follow-up was 65.5 months (5.5 years). A total of 46 new retinal tumours were detected in 21 patients. These new tumours had a size less than 1 disc diameter in 75% and were peripherally located in 78% of the cases, with a statistically significant preference for the horizontal meridians. No new tumours developed in the macular area. 50% appeared in children younger than 1 year and 80% before 2 years of age. 50% of the eyes with recurrences developed new tumours before 7.5 months following diagnosis, and 75% before 14 months. All patients showing recurrences did so before the age of 4.5.

Radial asymmetry in the topography of retinoblastoma. Clues to the cell of origin

Retinoblastoma is a malignancy of the human developing retina. In situ as well as in vitro studies have attributed tumoral histogenesis either to a primitive retinoblast with neuronal and glial differentiation potentials, or to a photosensory progenitor cell. Here it is shown in vivo that the retinal topography of 457 retinoblastoma and retinoma foci is radially asymmetrical. Tumor density appears to mimic the horizontal visual streak characteristic of red/green cone cell distribution. Such a non-random distribution seems to invalidate the hypothesis of a primitive multipotential neuroblast as the unique source of retinoblastoma and may support the view that retinoblastoma evolves along the cone cell lineage.

[Unusual presentation of retinoblastoma]

Among the 185 retinoblastoma patients seen at the Lausanne Retinoblastoma Clinic from 1963-1993, 24 (14%) first presented with another sign than classical leukocoria (60.5%) or strabismus (21.5%). Most of these atypical signs were related to inflammatory complications of unrecognized retinoblastoma; they consisted of low vision (1.5%), hypopyon (2%), ocular redness and pain (1.5%), ocular redness and buphtalmia (1.5%), as well as photophobia and headaches (1.5%). The presence of unexplained chronic ocular signs during childhood should always raise the possibility of an underlying retinal malignancy.

Pseudo low penetrance in retinoblastoma. Fortuitous familial aggregation of sporadic cases caused by independently derived mutations in two large pedigrees

OBJECTIVE

The disparate occurrence of few cases of retinoblastoma in the same extended pedigree confronts us with the unsolved problem of a low-penetrant autosomal-dominant trait vs fortuitous familial aggregation of sporadic cases. Determination as to whether the disease arises from a common inherited mutation or sporadic mutations has important implications for genetic counseling. This is illustrated in this report of two presumed low-penetrant retinoblastoma pedigrees characterized by two distantly affected relatives connected through apparently healthy carriers.

DESIGN

We mathematically modeled the inheritance patterns and calculated the a priori relative probabilities of heredity with low penetrance vs chance occurrence of independent mutations for each pedigree. The derived odds clearly show that the disease, which occurred twice in each family, most likely resulted from unrelated mutations. To prove this, extensive DNA testing was conducted, including determination of intragenic RB1 DNA sequence polymorphisms and screening for mutation using the polymerase chain reaction coupled with single-strand conformation polymorphism analysis.

PATIENTS

All living key members from both pedigrees were included.

RESULTS

Consistent with our initial expectation, there was no common intragenic haplotype or common germ-line mutation that segregated with the disease phenotype in either of these two families.

CONCLUSIONS

We therefore conclude that collateral incidence of retinoblastoma in these two pedigrees occurred by chance and not according to autosomal-dominant inheritance with low penetrance. Furthermore, our data provide the first evidence, to our knowledge, that related individuals may have independent mutations involving an identical gene locus, giving rise to an artefactual inheritance pattern.

Hypofractionation in retinoblastoma: an increased risk of retinopathy

Forty-four eyes in 38 children were treated between 1963 and 1991 by external radiotherapy for retinoblastoma. Treatment modalities varied widely during this period; in addition to radiotherapy there was chemotherapy (16/44), photocoagulation (14/44), and laser therapy or cryotherapy (14/44). Treatment technique and dose fractionation also varied widely; lateral beam technique (39/44) versus anterior or anterior/lateral beam; doses per fraction ranged from 1 to 4.5 Gy, total doses from 30 to 61.5 Gy, and overall times from 22 to 49 days. Patients were followed at 3-month intervals, and actuarial survival at 10 years was 88%, with 62% local control. Ten eyes showed clinical evidence of retinopathy. A multivariate analysis of factors associated with increased risk of retinopathy was carried out using the Cox proportional hazards model and the mixture model of Farewell. The estimated latent time was 17 months (95% confidence interval, 14-20 months). The only factors found to be significantly associated with retinopathy were total dose multiplied by dose per fraction, or total dose normalized to the equivalent total dose in 2-Gy fractions as estimated from the LQ model, and these gave equivalent descriptions. There were trends (not significant) for increased risk of retinopathy when treatments included chemotherapy or photocoagulation, and for decreased risk (also not significant) when cryotherapy was used in conjunction with radiotherapy. No significance could be attached to any of the following: number of sites per eye, Reese-Ellsworth stage, and family history. We conclude that hypofractionation carries a significant risk for retinopathy in the treatment of retinoblastoma.

Retinoblastoma. Unusual warning and clinical signs

Three clinical cases have been chosen to illustrate the pitfalls that can be encountered when warning signs other than leukokoria or strabismus indicate possible retinoblastoma. The first case, a four-year-old boy, was admitted to hospital after an accident, presenting uveitis, glaucoma and a subluxated lens. He was suffering from unilateral retinoblastoma, already exteriorized and the cause of death some months later. The second case, and 11-month-old female child was seen on fundus examination to present a yellowish elevated calcified mass which turned out to be tuberous sclerosis. The third patient, a 43-year-old male, father of two children suffering from retinoblastoma, was found on routine examination to be carrying a partially-calcified retinal tumour. Subsequent haemorrhaging rendered enucleation necessary and microscopic examination confirmed the diagnosis of retinoma. The diagnosis of retinoblastoma should always be kept in mind whenever an intraocular mass is revealed or where there are unexplained atypical ocular signs.

Paternal selection favoring mutant alleles of the retinoblastoma susceptibility gene

Penetrance and segregation rates of mutant Rb-1 alleles were assessed in all 51 members of eight kindreds with hereditary retinoblastoma by concomitant ophthalmologic examination and determination of seven intragenic restriction fragment length polymorphisms (RFLPs). Penetrance was in the range reported in the literature except for one family in which it was only 42.8%. However, the odds of transmitting a mutant Rb-1 allele from one generation to the next were 25:9 in this population, much above the Mendelian 1:1 ratio (P less than 0.025). This preferential transmission was discovered through the use of molecular information. Further analysis revealed that this distortion was due to preferential inheritance among children of male carriers (18:4, P less than 0.005). No difference from a 1:1 segregation ratio could be detected among the children of female carriers (7:5). These findings were consistent with a review of relevant data in the literature.

[Retinoma and phtisis bulbi: benign expression of retinoblastoma]

Systematic investigation of families of children suffering from retinoblastoma reveals more and more cases of retinoma or phthisis bulbi, cases which used to be called "spontaneous regression". Between 1975 and 1991, we have in this way discovered 11 cases (7%) certain to be carrying retinoma or phthisis bulbi, and a further 5 cases where the same diagnosis is highly probable. Of the 11 certain cases, 5 are unilateral, 6 bilateral, and 8 present family history of the disease. Of the total number of 17 eyes, 16 present retinoma, 1 phthisis bulbi. On clinical examination, all (100%) showed characteristic lesions in the form of greyish homogenous elevated masses in the vitreous cavity. 11 presented calcifications (69%) and in 14 disturbance of the pigment epithelium occurred (87%). The average follow-up is 4 years. Of the 11 patients, 8 are of procreating age and have up to now 25 offsprings. Amongst these, 15 have retinoblastoma (60%), 2 retinoma and phthisis bulbi (8%). All except one of the retinoblastoma cases are bilateral. This study would appear to show that retinoma occurs with a higher frequency than that which is usually given. The figures show clearly that retinoblastoma and retinoma derive from the same genetic disturbances, possibly at different times during cell maturation, and consequently require the same investigation and follow-up.

Retinoma. Case studies

The new concept of retinoma, or retinocytoma, brings up the rare 'spontaneous regressions' long-reported in the literature. Systematic investigation of all relatives of children suffering from retinoblastoma is showing up more and more retinoma cases undetected until now. From 1975 to 1990 the authors have identified 11 retinoma cases amongst 103 retinoblastoma patients and their families. The average age of the retinoma patients is 23 years with a mean follow-up of four years. There are four bilateral cases, one of which with phthisis bulbi, three unilateral retinomas associated with retinoblastoma of the fellow-enucleated eye, and four unilateral cases. Of the 11 retinomas, seven patients have a family history of retinoblastoma. Of the seven patients of procreating age, 16 offspring, three abortions and two miscarriages are noted. Of the 16 offspring, 12 developed retinoblastoma, 11 of which bilaterally. One 21-year-old patient presented in the process of malignant transformation. A child, enucleated for retinoblastoma of one eye and showing lesions conforming to retinoma in the fellow eye at two years of age, suffered an osteosarcoma when nine years old. The authors' data show that retinoblastoma and retinoma follow the same genetic changes and consequently require the same investigation and follow-up. This study indicates a frequency of retinoma of 10% amongst retinoblastoma patients and their families which is higher than that usually quoted.

[Astigmatism in cataract surgery. Retrospective study of 1,304 cases]

We performed a retrospective computerized study of 1304 consecutive cataract extractions, of which 251 were intracapsular and 1053 extracapsular. The analysis of surgically induced astigmatism after a mean follow-up of 22.8 months involved 639 cases. Operations were performed by two experienced surgeons using a similar and standardized technique; however the location of the incision varied without selecting patients: 391 were corneal, 248 limbal. We found that corneal incision gives significantly more against-the-rule astigmatism (average -0.61 dptr) than limbal incision (average -0.32 dptr). The suture induced astigmatism has no determining effect on the final astigmatism (correlation coefficient = 0.011). Selective suture cutting is an interesting technique for an individual dosage of the amount of final astigmatism.

[Lausanne study of retinoblastoma, 1986-90: deletion of esterase D locus in a collective of 128 patients]

Activity and phenotype of red blood cell esterase D were systematically determined in a population of 128 retinoblastoma patients from 99 families and compared to 158 controls, in order to detect a chromosome 13q14 deletion. Among these patients 12 were healthy carriers and 116 affected carriers of a mutant allele of the retinoblastoma susceptibility gene (110 retinoblastoma, 5 retinoma, 1 phtisis bulbi). 4 patients were found to have decreased ESD levels in connection with 13q14 deletion which was confirmed by chromosome analysis. The data presented here suggest that ESD quantification has a high specificity and sensitivity for the detection of homogenous chromosome 13 deletions in retinoblastoma patients.

[Complications of cataract surgery. Retrospective study of 1,304 cases]

This retrospective study concerns complications arising from 1304 first operations for cataract carried out between 1982 and 1987 by two surgeons having followed the same training and using the same techniques. Loss of vitreous (2.5%) cystoid macular edema (1.9%), and retinal detachement (1.1%) are those complications occurring most frequently in this series. Other serious complications, in descending order, are trauma (0.7%), iris prolaps (0.5%), corneal dystrophy (0.4%), pupillary block (0.3%), expulsive hemorrhage (0.15%), loss of the nucleus in the vitreous (0.07%), panophthalmia (0.07%). Secondary cataract was noted in 31% of cases.

[Treatment of retinoblastoma and results. Lausanne 1963-1989]

97 cases of retinoblastoma were studied with particular attention to methods of treatment and results. The series includes 41 unilateral cases (42%) and 56 bilateral cases (58%), giving a total of 153 eyes. Of these, 19 (20%) were familial cases. Immediate enucleation was necessary in 88 of the 153 eyes; 61 eyes received conservative treatment; 4 eyes, including one bilateral case, showed spontaneous recovery (retinomas). Conservative treatment consisted of high-voltage external beam irradiation in 43 cases, cryo or photocoagulation in 12 cases, and radioactive applicators in 6 cases. The mortality-rate in cases with over 2-years follow up is of 11%. In 65% of treated cases the eye was saved, with 87% of these retaining useful or central vision. The most serious complications are radiation retinopathy (19%), cataract (16%) and exsudative retinal detachment (9%).

Constitutional karyotype in retinoblastoma. Case report and review of literature

High resolution karyotype was performed in 13 retinoblastoma patients. A mosaic pattern for del(13)(q14.1;q14.3) was found in a girl with sporadic bilateral retinoblastoma and midface dysmorphism. In addition, 162 cases of 13q aberrations were reviewed, including 140 retinoblastoma patients and 22 non-penetrance 13q14 deletions. Some epidemiological and genetic involvements are discussed.

[Retinoblastoma and pseudoretinoblastoma: diagnostic study]

Between 1963 and 1987 admitted Lausanne University Eye Hospital 140 infants with suspected retinoblastoma. Of these, 98 (70%) were subsequently confirmed cases, while 42 (30%) were found to be suffering from a benign disorder. Among these pseudoretinoblastomas, Coats' disease was found to be the most prevalent (21%) in this study. The examination procedure is discussed and the importance of genetic research is emphasized.

A "new" allele of esterase D in a retinoblastoma family

We describe a new rare allele for esterase D (EsD) occurring in a Portuguese family with retinoblastoma in two generations.