Glucose-6-phosphate dehydrogenase aveiro: a de novo mutation associated with chronic nonspherocytic hemolytic anemia

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common X-linked enzyme abnormality. The clinical phenotype is variable but often predictable from the molecular lesion. Class I variants (the most severe forms of the disease) cluster within exon 10, in a region that, at the protein level, is believed to be involved in dimerization. Here we describe a de novo mutation (C269Y) of a new class I variant (G6PD Aveiro) that maps to exon 8. Mutant and normal alleles were found in both hematopoietic and buccal cells, indicating the presence of mosaicism. The available model of the protein predicts that this lesion lies in proximity to the dimer interface of the molecule. A possible mechanism to explain the severity of the defect is proposed. (Blood. 2000;95:1499-1501)

[The molecular basis of dominantly inherited beta-thalassemia]

In this study, we sought to clarity the molecular basis of a dominant inherited beta-thalassemia, found in heterozygosity in a northern Portuguese family with thalassemia intermedia. We characterized: i) the alpha-globin gene cluster structure; ii) the beta-globin gene cluster haplotype; and iii) the beta-thalassemia mutation. The alpha-globin gene cluster was structurally normal. The G-->T transversion at codon 121 of the beta-globin gene was found in the affected individuals in association with Orkin's haplotype V. This is an uncommon, though ubiquitous, mutation. Which has also been found, in association with different haplotypes, in several distant populations. It has only been observed in this three-generation family, in the Portuguese population. We suggest a mechanism to explain the genotype/phenotype correlation.

[Glucose-6-phosphate dehydrogenase deficiency in 2 girls]

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common erythrocyte enzymopathy, affecting over 400 million people worldwide. Portugal is a low prevalence country, but immigrants from endemic regions are common, particularly in the south of the country. In the present study, we report the laboratory findings observed in two black proband children with low G6PD enzyme activity (23 and 18%). The study also included their first-degree relatives. Both biochemical parameters (enzyme activity, electrophoretic mobility and cytochemical test) and genetic determinations (mutation and haplotype characterisation) were performed.

[Brain stem ischemia in a boy with resistance to C activated protein and elevated lipoprotein A]

INTRODUCTION

Activated protein C resistance is the most common hereditary coagulation abnormality. In the majority of cases it results from a point mutation Arg506-->Gln of the factor V gene, and characterized by a poor anticoagulant response to activated protein C.

CLINICAL CASE

We report the clinical case of a 6-year-old obese boy, who presented with acute hemiparesis. A cerebral MRI revealed an area of infarction in the left hemiprotuberance. Further investigation identified activated protein C resistance (heterozygosity for factor V Leiden) and elevation in lipoprotein (a). His mother also had factor V Leiden mutation. Prophylaxis with acetylsalicylic acid was instituted with favorable evolution.

CONCLUSIONS

This mutation, isolated, is usually asymptomatic, unless other risk factors coexist. Although venous thromboembolism seems to be the main clinical manifestation, recent reports consider that activated protein C resistance is also a risk factor for arterial thrombosis and stroke in children. We reinforce the need for systematic and thorough evaluation of etiology and risk factors in cases of stroke in children.

[Acting on clinical trials. Experience of organizations for the fight against AIDS]

This article analyses the action of organizations fighting against AIDS, from a sociological point of view, with regard to clinical trials conducted in France. It first refers to past work, and briefly describes how TRT5 was created (TRT5 is an interassociative group which defends the interests of persons suffering from HIV in clinical research). The organization of meetings, in 1993, between associative militants, methodologists and clinicians to discuss trial protocols with the support of the Agence Nationale de Recherches sur le Sida (ANRS) is an original experiment in France. Using a series of ethnographic observations made between 1994 and 1997, the article retraces the way in which, during these meetings, AIDS organizations took position on the methodology of controlled trials based on criteria of clinical effectiveness. It makes an analysis of the associative work done on this occasion on the information and consent sheets aimed at patients. Finally, it assesses the effect on associative mobilisation of current changes with regard to carrying out trials: the use of viral load as predictive markers of clinical effectiveness, and the wider access, outside trials, to molecules that are both more numerous and more effective.

Six previously undescribed pyruvate kinase mutations causing enzyme deficiency

Erythrocyte pyruvate kinase deficiency is the most common cause of hereditary nonspherocytic hemolytic anemia. We present 6 previously undescribed mutations of the PKLR gene associated with enzyme deficiency located at cDNA nt 476 G-->T (159Gly-->Val), 884 C-->T (295Ala-->Val), 943 G-->A (315Glu-->Lys), 1022 G-->A (341Gly-->Asp), 1511 G-->T (504Arg-->Leu), and 1528 C-->T (510Arg-->Ter). Two of these mutations are near the substrate binding site: the 315Glu-->Lys (943A) mutation may be involved in Mg2+ binding and 159Gly-->Val (476T) mutation has a possible effect on ADP binding. Four of six mutations produce deduced changes in the shape of the molecule. Two of these mutations, 504Arg-->Leu (1511T) and 510Arg-->Ter (1528T), are located at the interface of domains A and C. One of them (510Arg-->Ter) is a deletion of the C-terminal residues affecting the integrity of the protein. The 504Arg-->Leu mutation eliminates a stabilizing interaction between domains A and C. Changes in amino acid 341(nt 1022) from Gly to Asp cause local perturbations. The mutation 295Ala-->Val (884T) might affect the way pyruvate kinase interacts with other molecules. We review previously described mutations and conclude that there is not yet sufficient data to allow us to draw conclusions regarding genotype/phenotype relationship.

Clinical and haematological consequences of recurrent G6PD mutations and a single new mutation causing chronic nonspherocytic haemolytic anaemia

We have determined the causative mutation in 12 cases of glucose-6-phosphate dehydrogenase deficiency associated with chronic non-spherocytic haemolytic anaemia. In 11 of them the mutation we found had been previously reported in unrelated individuals. These mutations comprise seven different missense mutations and a 24 base pair deletion. G6PD Nara, previously found in a Japanese boy. Repeated findings of the same mutations suggests that a limited number of amino acid changes can produce the CNSHA phenotype and be compatible with normal development. The one new mutation we have found, G6PD Serres, is 1082 C-->T causing a 361 Ala-->Val substitution in the dimer interface where most other severe G6PD mutations are found. Now that several patients with the same mutation have been reported we can compare the resulting clinical phenotypes. For each mutation we find a reasonably consistent clinical picture, ranging from mild (G6PD Clinic) through moderate (G6PD Nashville) to severe (G6PD Beverly Hills and G6PD Nara).

Mutations in Emery-Dreifuss muscular dystrophy and their effects on emerin protein expression

Seventeen families with Emery-Dreifuss muscular dystrophy (EDMD) have been studied both by DNA sequencing and by emerin protein expression. Fourteen had mutations in the X-linked emerin gene, while three showed evidence of autosomal inheritance. Twelve of the 14 emerin mutations caused early termination of translation. An in-frame deletion of six amino acids from the C-terminal transmembrane helix caused almost complete absence of emerin from muscle with no localization to the nuclear membrane, although mRNA levels were normal. This shows that mutant emerin proteins are unstable if they are unable to integrate into a membrane. A 22 bp deletion in the promoter region was expected to result in reduced emerin production, but normal amounts of emerin of normal size were found in leucocytes and lymphoblastoid cell lines. This shows that DNA analysis is necessary to exclude emerin mutations in suspected X-linked EDMD. Emerin levels in female carriers often deviated from the expected 50% and this was due, in at least two families, to skewed emerin mRNA expression from the normal and mutated alleles. In one family with a novel deletion of the last three exons of the emerin gene, a carrier had a cardiomyopathy and very low emerin levels (<5% of normal) due to skewed X-inactivation. In the three autosomal cases of EDMD, emerin was normal on western blots of blood cells, which suggests that autosomal EDMD is not caused by indirect reduction of emerin levels.

Dominantly transmitted beta-thalassemia arising from the production of several aberrant mRNA species and one abnormal peptide

We describe a dominantly inherited beta-thalassemia intermedia phenotype observed in a five-generation Portuguese family. Carriers are characterized by moderate anemia, hypochromia, microcytosis, elevated hemoglobin (Hb)A2 and HbF levels, splenomegaly, hepatomegaly, and inclusion bodies in peripheral red blood cells after splenectomy. The molecular basis of this condition is a small deletion within the 5' consensus splicing sequence of the second intron of the beta-globin gene, IVS-II-4,5 (-AG). Reticulocyte RNA studies performed by reverse transcription-polymerase chain reaction (RT-PCR) and primer extension analysis showed three abnormally processed transcripts, which, upon sequencing, were shown to correspond to (1) skipping of exon 2, and (2) activation of two cryptic splice sites (between codons 59/60, and at IVS-II-47). In vitro translation studies of these patients' reticulocyte RNA have shown that at least one of these aberrant mRNA species is translated into an abnormally elongated peptide whose cytotoxic properties could, in part, be causing the atypical dominant mode of inheritance observed in this family. We suggest that this elongated beta chain is unable to combine with an alpha-globin chain to form a functional Hb molecule. Its degradation would, then, exhaust the proteolytic defense mechanism of the erythroid precursors, leading to inefficient proteolysis of the free alpha chains in excess.

Symmetrical enchondromatosis of the hands and feet in two sisters

We report two Portuguese sisters aged 9 and 12 years with symmetric well-circumscribed radiolucent cystic lesions on the long bone metaphysis of the hands and feet. The eldest also has soft tissue calcifications. They have no dysmorphic features and their growth is normal. Plasma values of parathyroid hormone (PTH), calcium, phosphorus, magnesium, and alkaline phosphatase are normal. Cerebral computed tomography (CT) scan shows no intracranial calcifications. A Raynaud phenomenon became evident during the last year in the eldest. The incisional biopsy of the left proximal metatarsial was performed through an area of typical radiographic appearance. The pathology specimen consisted of enchondroma tissue. The present cases are an extremely rare instance of this pathology, with symmetrical involvement of the hands and feet and a familial incidence.

Hysteroscopy and hysterography

Hysteroscopy and hysterography approach the uterine cavity in different ways and each has advantages and limitations. Hysteroscopy is more accurate for the diagnosis of abnormalities that project into the uterine cavity such as polyps, submucous myomas, endometrial hyperplasia, and endometrial adenocarcinoma. Contrast media used in hysterography enable the detection of lesions that penetrate the myometrium and congenital and acquired partitions of the uterine cavity. Diagnostic hysteroscopy, easily performed as an office procedure, should be the screening method of choice to search for uterine abnormalities except for the infertility patient who also requires a salpingogram. Hysterography should be considered as a complementary procedure only when the direct visual examination proves incomplete or inadequate. It is necessary for a thorough assessment of uterine malformations, adenomyosis, complex intrauterine adhesions, and uterine scars.

Novel promoter and splice junction defects add to the genetic, clinical or geographic heterogeneity of beta-thalassaemia in the Portuguese population

In order to delineate the spectrum and the relative abundance of beta-globin gene defects causing thalassaemia in the Portuguese population, a representative sample was analysed including 51 beta-thalassaemia carriers along with 26 patients representing different clinical phenotypes. Seven mutations were identified, four of which [codon 39 (C----T), 39%; intervening sequence (IVS) 1 nucleotide (nt) 1 (G----A), 26%; IVS 1 nt 110 (G----A), 17%; IVS 1 nt 6 (T----C), 15%] account for 97% of 93 beta-thalassaemia chromosomes. Two previously undescribed mutations, namely a C----T substitution at position--90 in the proximal CACCC box, and the deletion of nucleotides 4 and 5 (AG) in IVS2 were identified. The uncommon, though ubiquitous, G----T transversion at codon 121 was found once upon haplotype V. Direct prenatal diagnosis can be offered to 95% of couples at risk of bearing a thalassaemic child.

[Should one operate on bifocal tubal lesions in 1984? Apropos of 54 cases]

We have analysed 54 cases where the patients had two lesions in the tubes and were treated with microsurgery. The results of histological examinations show that chronic salpingitis in the major lesion. Infection was the aetiological cause in 76% of the cases. The results of microsurgical treatment are poor with a low rate of intra-uterine pregnancy: [19.4% (0.08-0.42) at 24-30 months for pregnancies that were continuing and for abortions, 11.7% (0.04-0.33) at 24-30 months using actuarial techniques for estimating pregnancies that were continuing]. There was a high risk of extra-uterine pregnancy [35% (0.18-0.58) at 24-30 months]. These results make us wonder whether microsurgery or in vitro fertilisation should be the treatment of preference in these cases where the tubes are affected in two areas.

[Longitudinal salpingotomy and fertility. Experimental study in the female rabbit]

A microsurgical technique of salpingotomy has been put forward for the treatment of ampullary distal lesions responsible for infertility. --An experimental research has been carried out before proposing any application on women. --The consequences on the fertility of a female rabbit of a longitudinal salpingotomy followed by a microsuture have been thoroughly studied. --21 female rabbits have been operated under microscope. --In every case the tubal permeability has been maintained and the rabbits became pregnant. --In some cases histological lesions in front of the suture area have been noticed, what aroused several possibilities as to their origin.

Contact hysteroscopy: another method of endoscopic examination of the uterine cavity

Recently there has been renewed interest in hysteroscopy which, since its discovery a century ago, has been in a state of uncertainty. Classical hysteroscopes all require the dilatation of the uterine cavity by the injection of a fluid under pressure. With contact hysteroscopy, the image is obtained by the applciation of the end of the apparatus against the uterine mucosa. This simplifies the equipment and opens up new possibilities. The results of more than 1,000 contact hysteroscopies done in the various circumstances of gynecology and the pathology of pregnancy are presented. The facility of this technique should contribute to the increased use of visual exploration of the uterine cavity, the advantages of which have already been shown.

[Vesico-uterine fistulae after Caesarean operation (author's transl)]

The vesico-uterine fistulae represent 4 per cent of all urogenital fistulae. They are rare and are found almost always after Caesarean operation. We have been able to find in the literature 110 vesico-uterine fistulae after Caesarean operation. They very rarely fail to be diagnosed if careful post-operative examination is made and the majority of them are discovered in the year following delivery. Urinary incontinence is the most common reason for consultation. More uncommon is amenorrhoea with menstruation through the bladder. Incontinent women are under constant threat of ascending urinary tract infection. Finally these women, whether they are incontinent or amenorrhoeic, are sterile. Their fertility remains diminished even after surgical cure of the fistula. The only treatment for those who complain of the condition is surgery. It should be undertaken after a careful gynaecological and urological assessment.

[Experimental study of the permeability of the fallopian tubes in the rabbit after division of the isthmus and microsurgical anastomosis (author's transl)]

The poor results of traditional reconstructive surgery of the Fallopian tubes have led the authors to try the possibilities of microsurgery in tubal sterility. The experimental animal chosen was the rabbit owing to its similarities with the Fallopian tube in women. After division of the isthumus, the tube was repermeabilised with a 10.0 single nylon thread under the operating microscope. A series of 11 rabbits were then coupled one mont after the operation. The pregnancy rate was 55%. This figure was much better than those obtained in the literature by non-microsurgical technics. One may hope to improve the results further by less traumatic surgery, better asepsis, and better control of fertility.

[Tubal repermeabilisation after sterilisation. Techniques and results (author's transl)]

Requests for repermeabilisation surgery, previously rare, are becoming more common. The indications for reparative surgery are analysed. Microsurgery is possible when the length of the remaining tube us adequate, more than 5 cm, and the ampulla undamaged. It is made difficult when the initial sterilisation procedure has destroyed too long a segment of the tube: electrocoagulation, resection of a long loop of tube. It is impossible when the ampulla and the adjacent portion of the tube have been damaged. Microsurgical techniques certainly improve the results of reparative surgery. After end-to-end anastomosis of the medial half of the tube, 60 to 75% of pregnancies going to term are obtained, and more than 90% secondary permeability. New methods for surgical sterilisation such as clips or rings should make it possible to achieve even better results in the future.

[Contact embryoscopy (author's transl)]

Prenatal diagnosis based on anatomic definition of the fetus in utero is an difficult task, in the first trimester of pregnancy. The authors have recently introduced a new method : contact embryoscopy which consist in applying the optic piece of a contact hysteroscope (diameter of six millemeters) to the intact and translucent ovular membranes by the cervix. They have performed fifty embryoscopy prior to termination of pregnancy at 8 to 12 weeks. In 41 cases, they have seen the hands of fetus with the fingers. If this technic fails, it is possible, later, to use Echography and fetoscopy. The side-effects are discussed. Contact embryoscopy would be particularly useful in the detection of malformations of the extremities, for instance : chondro-ectodermal dysplasia (Ellis Van Creveld Syndrome) or ectrodactily.