Guidelines for presymptomatic testing for Huntington's disease: past, present and future in France.

Huntington's disease was the first adult onset neurological disease for which presymptomatic genetic testing became possible. It served as a model for the approach which constituted a radical change in medical practice and provided an important framework for multi-step, multidisciplinary, counselling for at risk persons. We will review the historical context of guidelines and good clinical practices, the experiences of our team which covers more than 20 years of presymptomatic testing for Huntington's disease in France, and explore the impact of the new French legislation for the future of presymptomatic testing of diseases for which neither preventive measures nor curative treatments are yet available.

The involvement of the trans-generational effect in the high incidence of the hydatidiform mole in Africa.

INTRODUCTION: While the incidence of various chromosomal anomalies observed, including triploid partial moles is independent of the socio-economic level, higher incidences of complete hydatidiform mole "CHM" is generally associated with under developed areas. Moreover, studies have shown that some nutritional deficiencies are related to the abnormal development of oocytes and placenta. In Senegal and Morocco, the annual seasonal cycle contains one period with food shortages and the incidence of complete moles is significant. Accordingly, accurate statistical analyses have been performed in these two countries. METHODS: Each month during a one year period, we investigated the occurrence of normal conceptions, molar conceptions and the conception of the future patients in Senegal and Morocco. The comparisons of the conception dates for these three types of conception were analyzed using the Chi-squared test. RESULTS: 94% of the patients were conceived just prior to the period in the year with food shortages. Consequently, the development of the female embryos occurred under nutritional constraints, which negatively affect the recruitment of the vital factors required for the normal synthesis of DNA, proteins and placental differentiation. DISCUSSIONS: A nutritional deficiency in the mother at conception of their daughter (future patient) is implicated in the higher incidence of CHM in their daughters' filiation. These nutritional deficiencies during the first weeks of pregnancy will have repercussions on the normal development of the oocytes. Accordingly, these developmental impairments take place during the embryonic life of the future mothers of complete moles and not during the conception of the moles themselves.

[Critical approach to clinical trials: difficulties of such research in Lebanon]. / Approche critique des essais thérapeutiques : difficultés de ce type de recherche au Liban.

Clinical trials represent new steps in the progress of knowledge. Yet in spite of all the norms, guidelines and good clinical practices established since 1947, trials are still being published which seem to be, but in fact are not, well-conducted. Experts in planning and analyzing trial results have determined the factors that may affect clinical investigations at different phases. Among articles published over the last 30 years selected from Medline, one-third were biased. These biased articles were cited 2034 times. Clinical trials are designed to improve the treatment of particular diseases and to reduce mortality and morbidity. Nevertheless, other factors still appear to have an essential influence on the way clinical trials are conducted. It is surprising to see how often trials conclude that the drug of the pharmaceutical company initiating the study or funding it has the same efficiency, and sometimes is more efficient, than the drug it is being judged against. Perhaps, journals should objectively describe clinical trial protocols before publishing their results. Poor populations are still being abused by the pharmaceutical industry and more thought should be given to the notions of volunteers participating in trials and the compensation they receive. In Lebanon, the majority of these difficulties are encountered not only in multicenter international trials but are also seen in the lack of requirements for minimum safety measures and ethical standards when conducting national and regional trials. These insufficiencies raise important questions concerning their real objective.

The presymptomatic phase of Huntington disease.

Huntington disease is a neurodegenerative disorder transmitted as an autosomal dominant trait. It is the first neurological disease for which presymptomatic testing has been available for 20years in France. Follow-up of mutation carriers provided a better understanding of the presymptomatic phase of the disease and will change medical practice. Studying this phase led to the identification of clinical, imaging and plasma markers prior to motor onset, which will allow finding the optimal window for preventive treatment and follow-up of its efficacy.

Temsirolimus safety profile and management of toxic effects in patients with advanced renal cell carcinoma and poor prognostic features.

BACKGROUND: Temsirolimus, a novel inhibitor of mammalian target of rapamycin, has demonstrated prolonged overall survival and progression-free survival compared with interferon alfa (IFN) in patients with advanced renal cell carcinoma (RCC) and poor prognostic features. Adverse events (AEs) of any causality were previously reported, but AEs that were deemed temsirolimus related are of particular relevance for poor-risk patients and for defining mammalian target of rapamycin inhibitor-specific side-effects. PATIENTS AND METHODS: Patients with advanced RCC, no prior systemic therapy, and three or more of six poor-risk factors were randomly assigned to one of three groups: (i) IFN s.c. up to 18 MU thrice weekly, (ii) temsirolimus i.v. 25 mg weekly, or (iii) temsirolimus i.v. 15 mg weekly plus interferon s.c. 6 MU thrice weekly. RESULTS: Among 208 patients, the most common temsirolimus-related grades 3-4 AEs were anemia (13%), hyperglycemia (9%), and asthenia (8%). Grades 3-4 hypercholesterolemia (1%), hypertriglyceridemia (3%), and hypophosphatemia (4%) were also seen. Although pneumonitis occurred infrequently, vigilance for its development is needed. Guidelines for management of toxic effects are presented on the basis of available clinical experience. CONCLUSIONS: Temsirolimus-related grades 3-4 AEs were primarily metabolic in nature and easily controlled medically. In general, these did not negatively impact patient quality of life.

Homozygous mutation of the PHOX2B gene in congenital central hypoventilation syndrome (Ondine's Curse).

Homozygosity for a dominant allele is relatively rare and preferentially observed in communities with high inbreeding. According to the definition of true dominance, similar phenotypes should be observed in patients heterozygous and homozygous for a dominant mutation. However, the homozygous phenotype usually tends to be more severe than the heterozygous one. In these cases, the wild-type and mutant alleles are semi-dominant. Here we report a patient with a Congenital Central Hypoventilation Syndrome (CCHS) phenotype and homozygosity for a PHOX2B gene mutation leading to an alanine expansion shorter than the threshold hitherto observed in CCHS patients with a heterozygous mutation. This observation adds the concept of mutational threshold per se to the discussion about dominant and recessive alleles.

Revisiting metatropic dysplasia: presentation of a series of 19 novel patients and review of the literature.

Metatropic dysplasia (MD-OMIM: 156530 and 250600) is a rare chondrodysplasia characterized by short limbs with limitation and enlargement of joints and usually severe kyphoscoliosis, first described in 1893. Up until now, 81 other patients have been reported. The phenotypic variability of MD has led to a classification based on radiological anomalies dividing into three different types: a lethal autosomal recessive form, an autosomal recessive non-lethal form and a non-lethal autosomal dominant form with less severe radiographs manifestations and a better clinical outcome. Here, we report on clinical and radiological features of 19 novel MD patients. We describe new radiological features, including precocious calcification of hyoid and cricoid cartilage, irregular and squared-off calcaneal bones and severe hypoplasia of the anterior portion of first cervical vertebrae. In addition, the observation of an overlap between the autosomal recessive non-lethal form and the non-lethal autosomal dominant form, the rarity of sibship recurrences and the observation of vertical transmissions of MD in the literature argue in favor of an autosomal dominant mode of inheritance for all MD types. This hypothesis is reinforced by the use of the statistical single ascertainment method that rejects the hypothesis of an autosomal recessive mode of inheritance responsible for MD. Therefore, we propose that recurrence in sibs is due to gonadal mosaicism.

Epistatic interactions with a common hypomorphic RET allele in syndromic Hirschsprung disease.

Hirschsprung disease (HSCR) stands as a model for genetic dissection of complex diseases. In this model, a major gene, RET, is involved in most if not all cases of isolated (i.e., nonsyndromic) HSCR, in conjunction with other autosomal susceptibility loci under a multiplicative model. HSCR susceptibility alleles can harbor either heterozygous coding sequence mutations or, more frequently, a polymorphism within intron 1, leading to a hypomorphic RET allele. On the other hand, about 30% of HSCR are syndromic. Hitherto, the disease causing gene has been identified for eight Mendelian syndromes with HSCR: congenital central hypoventilation (CCHS), Mowat-Wilson (MWS), Bardet-Biedl (BBS), Shah-Waardenburg (WS4), cartilage-hair-hypoplasia (CHH), Smith-Lemli-Opitz (SLO), Goldberg-Sprintzsen (GSS), and hydrocephalus due to congenital stenosis of the aqueduct of sylvius (HSAS). According to the HSCR syndrome, the penetrance of HSCR trait varies from 5 to 70%. Trisomy 21 (T21) also predisposes to HSCR. We were able to collect a series of 393 patients affected by CCHS (n = 173), WS4 (n = 24), BBS (n = 51), MWS (n = 71), T21 (n = 46), and mental retardation (MR) with HSCR (n = 28). For each syndrome, we studied the RET locus in two subgroups of patients; i.e., with or without HSCR. We genotyped the RET locus in 393 patients among whom 195 had HSCR, and compared the distribution of alleles and genotypes within the two groups for each syndrome. RET acts as a modifier gene for the HSCR phenotype in patients with CCHS, BBS, and Down syndrome, but not in patients with MWS and WS4. The frequent, low penetrant, predisposing allele of the RET gene can be regarded as a risk factor for the HSCR phenotype in CCHS, BBS, and Down syndrome, while its role is not significant in MWS and WS4. These data highlight the pivotal role of the RET gene in both isolated and syndromic HSCR.

ReFacto and Advate: a single-dose, randomized, two-period crossover pharmacokinetics study in subjects with haemophilia A.

ReFacto is a recombinant B-domain-deleted, monoclonal antibody-purified, solvent-detergent-treated factor VIII (BDDrFVIII) with no albumin added to the final formulation. Although ReFacto has been shown to be bioequivalent to a plasma-derived FVIII product (Hemophil-M) in a randomized, crossover pharmacokinetic (PK) study, the comparability of ReFacto with the full-length (complete sequence) recombinant FVIII (FLrFVIII, Advate) product has not been previously examined in this manner. The primary objective of this study was to compare the PKs of ReFacto with those of Advate in patients with severe haemophilia A. This was a third-party unblinded, randomized, multicentre, two-period crossover PKs study of ReFacto and Advate in subjects with severe haemophilia A (FVIII:C < or =1%). Blood samples were collected over a 48-h period after i.v. administration of each of the FVIII products. FVIII:C was determined using the chromogenic substrate assay (CSA) in a central laboratory. The plasma FVIII:C PK parameters of ReFacto and Advate were determined using non-compartmental analysis. Bioequivalence was assessed on maximum plasma concentration (C(max)) and the area under the plasma concentration vs. time curves (AUCs) using an anova. The two products were judged to be equivalent if the 90% confidence limits of the ratio of the geometric mean values of C(max) and AUCs fell within the interval of 80-125%. Results from this PKs comparison of two different rFVIII products, using chromogenic substrate assay to measure FVIII:C, showed that ReFacto and Advate are bioequivalent to each other.

[Identification and management of HNPCC syndrome (hereditary non polyposis colon cancer), hereditary predisposition to colorectal and endometrial adenocarcinomas]. / Identification et prise en charge du syndrome HNPCC (hereditary non polyposis colon cancer). Prédisposition héréditaire aux cancers du côlon, du rectum et de l'utérus.

BACKGROUND: The HNPCC syndrome (hereditary nonpolyposis colon cancer) is an inherited condition defined by clinical and genealogical information, known as Amsterdam criteria. In about 70% of cases, HNPCC syndrome is caused by germline mutations in MMR genes, leading to microsatellite instability of tumor DNA (MSI phenotype). Patients affected by the disease are at high risk for colorectal and endometrial carcinomas, but also for small intestine, urothelial, ovary, stomach and biliary tract carcinomas. HNPCC syndrome is responsible for 5% of colorectal cancers. Identification and management of this disease are part of a multidisciplinary procedure. METHODS: Twelve experts have been mandated by the French Health Ministry to analyze and synthesize their consensus position, and the resulting document has been reviewed by an additional group of 4 independent experts. MAIN RECOMMENDATIONS: The lack of sensitivity of Amsterdam criteria in recognizing patients carrying a MMR germline mutation led to an enlargement of these criteria for the recruitment of possible HNPCC patients, and to a 2-steps strategy, asking first for a tumor characterization according to MSI phenotype, especially in case of early-onset sporadic cases. The identification of germline MMR mutations has no major consequence on the cancer treatments, but influences markedly the long-term follow-up and the management of at-risk relatives. Gene carriers will enter a follow-up program regarding their colorectal and endometrial cancer risks, but other organs being at low lifetime risk, no specific surveillance will be proposed.

Mutations of the RET gene in isolated and syndromic Hirschsprung's disease in human disclose major and modifier alleles at a single locus.

BACKGROUND: In Hirschsprung's disease (HSCR), a hypomorphic allele of a major gene, RET, accounts for most isolated (non-syndromic) cases, along with other autosomal susceptibility loci under a multiplicative model. However, some syndromic forms of HSCR are monogenic entities, for which the disease causing gene is known. OBJECTIVE: To determine whether RET could be considered a modifier gene for the enteric phenotype on the background of a monogenic trait. METHODS: The syndromic HSCR entities studied were congenital central hypoventilation (CCHS) and Mowat-Wilson syndrome (MWS), caused by PHOX2B and ZFHX1B gene mutations, respectively. The RET locus was genotyped in 143 CCHS patients, among whom 44 had HSCR, and in 30 MWS patients, among whom 20 had HSCR. The distribution of alleles, genotypes, and haplotypes was compared within the different groups. To test the interaction in vivo, heterozygous mice were bred for a null allele of Phox2b and Ret genes. RESULTS: RET was shown to act as a modifier gene for the HSCR phenotype in patients with CCHS but not with MWS. The intestine of double heterozygote mice was indistinguishable from their littermates. A loss of over 50% of each gene function seemed necessary in the mouse model for an enteric phenotype to occur. CONCLUSIONS: In CCHS patients, the weak predisposing haplotype of the RET gene can be regarded as a quantitative trait, being a risk factor for the HSCR phenotype, while in MWS, for which the HSCR penetrance is high, the role of the RET predisposing haplotype is not significant. It seems likely that there are both RET dependent and RET independent HSCR cases.

A postmarketing surveillance study of the safety and efficacy of ReFacto (St Louis-derived active substance) in patients with haemophilia A.

This clinical trial evaluated the safety and efficacy of ReFacto (St Louis-derived active substance) in patients with severe or moderately severe haemophilia A over a period of 6 months or 50 exposure days (EDs), whichever occurred first. Sixty patients, 58 previously treated and two previously untreated, were enrolled into this study. This was an open-label, multicentre, postmarketing surveillance study in which patients received prophylaxis or on-demand treatment as determined by their doctor. Surgical prophylaxis was evaluated in seven patients requiring elective surgery. Thirty-two patients aged <1 to 66 years (median 19.5) received prophylaxis and 28 patients, aged 1-71 years (median 33.5), received on-demand treatment. The majority of patients had severe haemophilia A (FVIII:C < 2%): 84.4% in the prophylaxis group and 85.7% in the on-demand group. Prophylaxis with ReFacto was associated with a median of 6.7 bleeds per year (range: 0-37). The investigator's assessment of final outcome for prophylactic treatment was excellent or effective for 93.1% of patients. ReFacto resolved 92.8% of bleeds with one or two infusions. The investigator's assessment was excellent or good for 98.2% of bleeds treated with ReFacto. Haemostasis was achieved for all seven surgical cases and ReFacto gave an excellent or good response for each. The nature and incidence of adverse events was as expected and no new safety concerns emerged. One previously treated patient (PTP) developed a high-titre inhibitor (maximum 75 BU) and one minimally treated patient (MTP) developed a low-titre inhibitor while on the study but eventually achieved high titres (maximum 30 BU) after immune tolerance therapy was initiated with a plasma-derived FVIII product. One previously untreated patient (PUP) developed a transient low-titre inhibitor (0.4 BU). Other serious adverse events (SAEs) were unrelated to study treatment. There were no allergic events. The results of this study are consistent with the previously published ReFacto pivotal studies.

[HNPCC syndrome (hereditary non polyposis colon cancer): identification and management]. / Le syndrome HNPCC (hereditary non polyposis colon cancer): identification et prise en charge.

BACKGROUND: The hereditary non-polyposis colon cancer (HNPCC) syndrome is an inherited condition defined by clinical and genealogical information, known as Amsterdam criteria. In about 70% of cases, HNPCC syndrome is caused by germline mutations in MMR genes, leading to microsatellite instability of tumor DNA (MSI phenotype). Patients affected by the disease are at high risk for colorectal and endometrial carcinomas, but also for other organs tumors. HNPCC syndrome is responsible for 5% of colorectal cancers. MAJOR ASPECTS: The lack of sensitivity of Amsterdam criteria in recognizing patients carrying a MMR germline mutation led to an enlargement of these criteria for the recruitment of possible HNPCC patients, and to a two-steps strategy, asking first for a tumor characterization according to MSI phenotype, especially in case of early-onset sporadic cases. FURTHER DEVELOPMENTS: The identification of germline MMR mutations has no major consequence on the cancer treatments, but influences markedly the long-term follow-up and the management of at-risk relatives. Gene carriers will enter a follow-up program regarding their colorectal and endometrial cancer risks; other organs being at low lifetime risk, no specific surveillance will be proposed.

Do parents and grandparents of patients with achondroplasia have a higher cancer risk?

Several studies, performed according to hypotheses based on teratogenesis and carcinogenesis have tried to answer the question: Do parents of children with congenital anomalies have a higher cancer risk? If the general answer is no, however, a higher risk for cancer was reported in the parents of children with cleft lip/palate (Zhu et al. [2002: Br J Cancer 87:524-528]). In achondroplasia, the neo-mutations are from paternal origin raising the hypothesis of the existence of a "mutator" gene acting in male meiosis and in somatic, mitotic cells in both sexes which may favor also the occurrence of cancer. In order to test this hypothesis, a questionnaire was sent to people with non-familial achondroplasia, asking for cancer, lymphoma, and leukemia in their parents and grandparents. In the hypothesis tested, the maternal lineage was the control. One hundred forty eight answers were obtained from 76 males and 72 females with achondroplasia. Out of them 68 had parents and/or grandparents with cancer. Among the grandparents of people with achondroplasia there were 36 cancers including two lymphomas in the paternal grandparents, 20 cancers including two chronic myeloid leukemia (CML) in the paternal grandmothers, 22 cancers including two CML in the maternal grandfathers, and two cancers in the maternal grandmothers. Paternal grandfathers and grandmothers had significantly more cancers (56) than maternal grandfathers and grandmothers (24) (chi(2)-test = 14.80, P < 0.001). In conclusion, paternal grandfathers and grandmothers of people with achondroplasia had significantly more cancers than maternal grandfathers and grandmothers. This result raises hypotheses in relationship with the paternal origin of neo-mutations in achondroplasia.

[Parent's information and prenatal diagnosis of cerebral malformation with an uncertain prognosis]. / Information des couples et diagnostic prénatal d'une malformation cérébrale à pronostic incertain: analyse des pratiques.

UNLABELLED: Fetal ultrasounds examinations allow identification of brain malformations; announce of diagnosis and information about prognosis may be difficult when malformation is rare and prognosis uncertain. OBJECTIVES: In this study we tried to analyze how fetal imaging for prenatal screening was organized and how couples were managed and supported. METHODS: We focused on the procedures used to inform couples: content, method of delivery and consequences. A referent physician in each large multidisciplinary center for prenatal diagnosis in Paris area was questioned by semi-directed interview. RESULTS: Our study showed that it is difficult to standardize the way in which information is supplied before and after fetal ultrasounds examination; uncertainty about prognosis led more often to abortion. CONCLUSION: Thus, couples should have clear and complete information provided by a multidisciplinary team including specialists particularly concerned by the malformation (neuropediatrician and/or neurosurgeon)--moreover when prognosis is uncertain, in order to support them, and to accompany their decision concerning pregnancy.

Phenotypic variability in autosomal recessive axonal Charcot-Marie-Tooth disease due to the R298C mutation in lamin A/C.

Autosomal recessive forms of axonal Charcot-Marie-Tooth (ARCMT2) disease are frequent in some areas, such as North Africa and the Middle East, since consanguineous marriages are still common there. Recently, a unique homozygous mutation in LMNA, which encodes lamin A/C, a component of the nuclear envelope, was identified in members of three Algerian families with ARCMT2 linked to chromosome 1q21.2-q21.3. In the present study we describe a group of 21 ARCMT2 patients from seven unrelated Algerian families with the same R298C mutation in the lamin A/C gene and marked variability of the clinical phenotype. There is a wide range of age of onset, from 6 to 27 years, with a mean of 14.4 +/- 4.6 years. The course of the disease varies considerably from one patient to another. Twelve patients with a disease duration of 10-15 years had a severe CMT phenotype with distal wasting and weakness of all four limbs and areflexia associated with involvement of the proximal lower limb muscles. In contrast, nine patients had the classical CMT phenotype with mild functional disability without proximal lower limb involvement after a disease duration of 5-18 years. Electrophysiological studies showed a median motor nerve conduction velocity (MNCV) in the normal range in almost all the patients. MNCV and compound muscle action potential (CMAP) values were inversely correlated with the disease duration and the MNCV was strictly related to the CMAP, strongly supporting a pure axonal process without a demyelinating component. Six patients had a nerve biopsy, which revealed severe rarefaction of myelinated fibres in all cases and an increased density of unmyelinated fibres in the majority of cases. In conclusion, the ARCMT2 associated with the R298C mutation differs from other types of ARCMT2. The variability among patients in the age of onset and the course of the disease strongly suggests the action of modifying genes, which remain to be identified.

[Towards an improved antenatal screening for cystic fibrosis]. / Vers un meilleur dépistage prénatal de la mucoviscidose.

BACKGROUND: Cystic Fibrosis is an autosomal and recessive lethal disease which affects in France one newborn in 3.000. New technologies may afford quite a cheap and efficient screening for a large set of mutations within the same assay in order to test their presence or absence. These procedures are very valuable for prenatal diagnosis for further pregnancies when couples at risk have been identified through a first affected newborn. But, for carriers or couples at risk before the birth of a first child, these antenatal screening methods remain of limited efficacy. However carrier screening would be the only way, on a public health standpoint, to decrease the disease frequency as no therapy seems to emerge till now. Recently hyperechogenic fetal bowel at routine ultrasound in the second trimester has been recognized to be associated with various deleterious conditions, especially cystic fibrosis. These observations lead praticians to investigate for parent CFTRmutations screening and subsequent prenatal diagnosis if the two parents are carriers. METHODS: Through data issued from two prospective investigations, our study aimed at the estimation of both the sensibility and efficiency of the screening for cystic fibrosis using ultrasound foetal bowel examination. RESULTS: Using the frequency of the disease in the population and the number of affected fetuses within the hyperechoic sample (20 in 641 in a recent study), our analysis may lead to the conclusion that fetal echogenic bowel may concern about 0.75% of fetuses. CONCLUSION: Orders of magnitude of the sensibility and efficiency of cystic fibrosis screening through fetal echogenic bowel are calculated and lead to the conclusion that sonographic screening might decrease the number of affected newborn more than two time less.