Medical biology in France: evolution and issues / Rapport des Académies nationales de médecine et de pharmacie. La biologie médicale en France : évolutions et enjeux

Medical biology is an essential part of patient care, both for the diagnosis and monitoring of diseases and for certain therapeutic advances. However, in recent years, it has been confronted with fundamental questions concerning its future. This report is the follow-up to the one published in 2018 by the National Academies of Medicine and Pharmacy and unfortunately only confirms a strong deterioration at all levels. The public authorities do not assume their role of regulator, thus allowing the excessive financialization of Medical Biology to grow considerably and lead to disproportionate groupings of Medical Biology Laboratories (MBL), destructive and sources of health risks. The result is that the Medical Biology Laboratories in towns, which are already known to be poorly distributed, are gradually becoming simple sampling sites, with patients finding themselves alone, often anxious, with their results sent to them by Internet without interpretation. Moreover, although progress in the field of Medical Biology is incredible and should constitute a major pole of attraction for young people, the disaffection of the discipline is total and worrying. Finally, innovation, in the context of current technological progress: connected devices, artificial intelligence and big data, represents a major challenge for the future. Here again, little or nothing is being done, even though the challenges are immense. After these alarming observations, the report will end with a series of recommendations aimed at optimizing the entry of MBL into a new era.

La biologie médicale est un maillon essentiel de la prise en charge des patients, tant pour le diagnostic et le suivi des maladies que pour certaines avancées thérapeutiques. Elle est toutefois, depuis quelques années, confrontée à des questions fondamentales concernant son avenir. Le présent rapport s'inscrit dans le prolongement de celui publié en 2018 par les Académies nationales de médecine et de pharmacie et ne fait malheureusement que conforter une forte dégradation à tous les niveaux. Les pouvoirs publics n'assument pas leur rôle de régulateur, permettant ainsi que la financiarisation à outrance de la biologie médicale s'amplifie considérablement et conduise à des regroupements démesurés des laboratoires de biologie médicale (LBM), destructeurs et sources de risques sanitaires. Le résultat est que les LBM de ville, dont on connaît déjà la mauvaise répartition territoriale, deviennent progressivement de simples sites de prélèvements, les patients se retrouvant alors seuls, souvent angoissés, avec leurs résultats transmis par Internet sans interprétation. Par ailleurs, bien que les progrès dans le domaine de la biologie médicale soient incroyables et devraient constituer un pôle d'attractivité majeur pour les jeunes, la désaffection de la discipline est totale et inquiétante. Enfin, l'innovation, dans le cadre des progrès technologiques actuels : dispositifs connectés, intelligence artificielle et mégadonnées (big data), représente un enjeu majeur pour l'avenir. Là encore rien n'est fait, ou presque, alors que les chantiers sont immenses. Après ces constatations alarmantes, le rapport se terminera par une série de recommandations visant à optimiser l'entrée des LBM dans une nouvelle ère.

[Medical biology in the face of the evolution of health care needs]. / Rapport des Académies nationales de médecine et de pharmacie sur la biologie médicale La biologie médicale face aux défis de l'évolution des besoins de santé.

Since the publication of the ordinance of January 13th 2010, ratified by the law of May 30th 2013, medical biology in France has undergone a massive restructuration with the emergence of groups of several hundred laboratories. This evolution, which leads to a considerable reduction in the number of structures, causes numerous problems related to increased industrialization and financialization, difficulties of accreditation and disappearance of the proximity link between the biologist and the prescriber or the patient. It also leads to a clear disaffection of students, especially medical students, for this specialty whose medical character has been clearly affirmed by the law. This report takes stock of the current situation of medical biology and makes recommendations to strengthen the role of the medical biologist in the health system and patients' care.

VLITL is a major cross-ß-sheet signal for fibrinogen Aα-chain frameshift variants.

The first case of hereditary fibrinogen Aα-chain amyloidosis was recognized >20 years ago, but disease mechanisms still remain unknown. Here we report detailed clinical and proteomics studies of a French kindred with a novel amyloidogenic fibrinogen Aα-chain frameshift variant, Phe521Leufs, causing a severe familial form of renal amyloidosis. Next, we focused our investigations to elucidate the molecular basis that render this Aα-chain variant amyloidogenic. We show that a 49-mer peptide derived from the C-terminal part of the Phe521Leufs chain is deposited as fibrils in the patient's kidneys, establishing that only a small portion of Phe521Leufs directly contributes to amyloid formation in vivo. In silico analysis indicated that this 49-mer Aα-chain peptide contained a motif (VLITL), with a high intrinsic propensity for ß-aggregation at residues 44 to 48 of human renal fibrils. To experimentally verify the amyloid propensity of VLITL, we generated synthetic Phe521Leufs-derived peptides and compared their capacity for fibril formation in vitro with that of their VLITL-deleted counterparts. We show that VLITL forms typical amyloid fibrils in vitro and is a major signal for cross-ß-sheet self-association of the 49-mer Phe521Leufs peptide identified in vivo, whereas its absence abrogates fibril formation. This study provides compelling evidence that VLITL confers amyloidogenic properties to Aα-chain frameshift variants, yielding a previously unknown molecular basis for the pathogenesis of Aα-chain amyloidosis.

D25V apolipoprotein C-III variant causes dominant hereditary systemic amyloidosis and confers cardiovascular protective lipoprotein profile.

Apolipoprotein C-III deficiency provides cardiovascular protection, but apolipoprotein C-III is not known to be associated with human amyloidosis. Here we report a form of amyloidosis characterized by renal insufficiency caused by a new apolipoprotein C-III variant, D25V. Despite their uremic state, the D25V-carriers exhibit low triglyceride (TG) and apolipoprotein C-III levels, and low very-low-density lipoprotein (VLDL)/high high-density lipoprotein (HDL) profile. Amyloid fibrils comprise the D25V-variant only, showing that wild-type apolipoprotein C-III does not contribute to amyloid deposition in vivo. The mutation profoundly impacts helical structure stability of D25V-variant, which is remarkably fibrillogenic under physiological conditions in vitro producing typical amyloid fibrils in its lipid-free form. D25V apolipoprotein C-III is a new human amyloidogenic protein and the first conferring cardioprotection even in the unfavourable context of renal failure, extending the evidence for an important cardiovascular protective role of apolipoprotein C-III deficiency. Thus, fibrate therapy, which reduces hepatic APOC3 transcription, may delay amyloid deposition in affected patients.

Next generation sequencing on patients with LGMD and nonspecific myopathies: Findings associated with ANO5 mutations.

We studied 786 undiagnosed patients with LGMD or nonspecific myopathic features to investigate the role of ANO5 mutations in limb-girdle muscular dystrophies (LGMDs) and in nonspecific myopathies using the next generation sequencing (NGS) approach. In 160 LGMD patients, we first sequenced hotspot exons 5 and 20 and then sequenced the remaining part of the coding region. Another 626 patients, recruited using broader inclusion criteria, were directly analyzed by targeted NGS. By combining NGS and Sanger sequencing, we identified 33/786 (4%) patients carrying putative pathogenic changes in both alleles and 23 ANO5 heterozygotes (3%). The phenotypic spectrum is broader than expected, from hyperCKemia to myopathies, with lack of genotype/phenotype correlations. In particular, this is currently the largest screening of the ANO5 gene. The large number of heterozygotes for damaging mutations suggests that anoctaminopathies should be frequent and often nonpenetrant. We propose the multiple genetic testing by targeted NGS as a first step to analyze patients with nonspecific myopathic presentations. This represents a straightforward approach to overcome the difficulties of clinical heterogeneity of ANO5 patients, and to test, at the same time, many other genes involved in neuromuscular disorders.

Hereditary systemic amyloidosis due to Asp76Asn variant ß2-microglobulin.

We describe a kindred with slowly progressive gastrointestinal symptoms and autonomic neuropathy caused by autosomal dominant, hereditary systemic amyloidosis. The amyloid consists of Asp76Asn variant ß(2)-microglobulin. Unlike patients with dialysis-related amyloidosis caused by sustained high plasma concentrations of wild-type ß(2)-microglobulin, the affected members of this kindred had normal renal function and normal circulating ß(2)-microglobulin values. The Asp76Asn ß(2)-microglobulin variant was thermodynamically unstable and remarkably fibrillogenic in vitro under physiological conditions. Previous studies of ß(2)-microglobulin aggregation have not shown such amyloidogenicity for single-residue substitutions. Comprehensive biophysical characterization of the ß(2)-microglobulin variant, including its 1.40-Å, three-dimensional structure, should allow further elucidation of fibrillogenesis and protein misfolding.

[Amyloid polyneuropathies--biochemical and genetic aspects]. / Les polyneuropathies amyloïdes: aspects biochimiques et génétiques.

Familial amyloid polyneuropathies (FAP) are among the most frequent hereditary amyloidoses. These are serious, most often fatal diseases with autosomal dominant inheritance. FAP can be caused by mutations in four genes, namely those encoding transthyretin, Al-apoliprotein, gelsolin, and beta-2 microglobulin. Transthyretin is a tetramer composed of four identical subunits linked by non covalent bonds and bearing binding sites for thyroxine (T4) and retinol-binding protein (RBP). More than 120 transthyretin gene sequence variations have been characterized, of which only 80% seem to be pathogenic. Gene mutations can induce tetramer destabilization, thereby generating misfolded monomers that aggregate into insoluble amyloidfibrils. The mutation spectrum is highly variable across countries. For example, while the Val30Met mutation is found in 95% of the Portuguese and Swedish patient populations, high mutational heterogeneity is observed in France. Age of onset and clinical signs are influenced by numerous factors, especially the mutation type and the country, but the mechanisms underlying this variability are not fully clear. The three-dimensional structure of the normal transthyretin protein and a dozen mutants is now known, providing insights into the deleterious effects of mutations. A better understanding of the mechanisms involved in amyloid fibril formation has led to the development of drugs that inhibit transthyretin tetramer destabilization. It is hoped that, within afew years, such drugs will replace liver transplantation, which is currently the only curative treatment.

A new VCAN/versican splice acceptor site mutation in a French Wagner family associated with vascular and inflammatory ocular features.

PURPOSE: To detail the highly variable ocular phenotypes of a French family affected with an autosomal dominantly inherited vitreoretinopathy and to identify the disease gene. METHODS: Sixteen family members with ten affected individuals underwent detailed ophthalmic evaluation. Genetic linkage analysis and gene screening were undertaken for genes known to be involved in degenerative and exudative vitreoretinopathies. Qualitative reverse transcriptase-PCR analysis of the versiscan (VCAN) transcripts was performed after mutation detection in the VCAN gene. RESULTS: The first index patient of this French family was referred to us because of a chronic uveitis since infancy; this uveitis was associated with exudative retinal detachment in the context of a severe uncharacterized familial vitreoretinopathy. Genetic linkage was obtained to the VCAN locus, and we further identified a new pathogenic mutation at the highly conserved splice acceptor site in intron 7 of the VCAN gene (c.4004-2A>T), which produced aberrantly spliced VCAN transcripts. CONCLUSIONS: Extensive molecular investigation allowed us to classify this familial vitreoretinopathy as Wagner syndrome. This study illustrates the need to confirm clinical diagnosis by molecular genetic testing and adds new ocular phenotypes to the Wagner syndrome, such as vascular and inflammatory features.

Synchrotron x-ray microdiffraction reveals intrinsic structural features of amyloid deposits in situ.

Amyloidoses are increasingly recognized as a major public health concern in Western countries. All amyloidoses share common morphological, structural, and tinctorial properties. These consist of staining by specific dyes, a fibrillar aspect in electron microscopy and a typical cross-ß folding in x-ray diffraction patterns. Most studies that aim at deciphering the amyloid structure rely on fibers generated in vitro or extracted from tissues using protocols that may modify their intrinsic structure. Therefore, the fine details of the in situ architecture of the deposits remain unknown. Here, we present to our knowledge the first data obtained on ex vivo human renal tissue sections using x-ray microdiffraction. The typical cross-ß features from fixed paraffin-embedded samples are similar to those formed in vitro or extracted from tissues. Moreover, the fiber orientation maps obtained across glomerular sections reveal an intrinsic texture that is correlated with the glomerulus morphology. These results are of the highest importance to understanding the formation of amyloid deposits and are thus expected to trigger new incentives for tissue investigation. Moreover, the access to intrinsic structural parameters such as fiber size and orientation using synchrotron x-ray microdiffraction, could provide valuable information concerning in situ mechanisms and deposit formation with potential benefits for diagnostic and therapeutic purposes.

Genotype-phenotype correlations of TGFBI p.Leu509Pro, p.Leu509Arg, p.Val613Gly, and the allelic association of p.Met502Val-p.Arg555Gln mutations.

PURPOSE: Investigate the genotype-phenotype correlations for five TGFBI (transforming growth factor, beta-induced) mutations including one novel pathogenic variant and one complex allele affecting the fourth FAS1 domain of keratoepithelin, and their potential effects on the protein's structure. METHODS: Three unrelated families were clinically diagnosed with lattice corneal dystrophy (CD) and one with an unclassified CD of Bowman's layer. Mutations in the TGFBI gene were detected by direct sequencing, and the functional impact of each variant was predicted using in silico algorithms. Corneal phenotypes, including histological examinations, were compared with the literature data. Furthermore, molecular modeling studies of these mutations were performed. RESULTS: Two distinct missense mutations affecting the same residue at position 509 of keratoepithelin: p.Leu509Pro (c.1526T>C) and p.Leu509Arg (c.1526T>G) were found to be associated with a lattice-type CD. The novel p.Val613Gly (c.1828T>G) TGFBI mutation was found in a sporadic case of an Algerian individual affected by lattice CD. Finally, the Bowman's layer CD was linked to the association in cis of the p.Met502Val and p.Arg555Gln variants, leading to the reclassification of this CD as atypical Thiel-Behnke CD. Structural modeling of these TGFBI mutations argues in favor of these mutations being responsible for instability and/or incorrect folding of keratoepithelin, predictions that are compatible with the clinical diagnoses. CONCLUSIONS: Description of a novel TGFBI mutation and a complex TGFBI allele further extends the mutational spectrum of TGFBI. Moreover, we show convincing evidence that TGFBI mutations affecting Leu509 are linked to the lattice phenotype in two unrelated French families, contrasting with findings previously reported. The p.Leu509Pro was reported to be associated with both amyloid and non-amyloid aggregates, whereas p.Leu509Arg has been described as being responsible for Epithelial Basement Membrane Dystrophy (EBMD).

Longest form of CCTG microsatellite repeat in the promoter of the CD2BP1/PSTPIP1 gene is associated with aseptic abscesses and with Crohn disease in French patients.

PURPOSE: Aseptic abscesses syndrome (AA) is an inflammatory disease in which non-infectious deep abscesses develop; these respond quickly to corticosteroids. AA is associated with Crohn disease (CD) in 57% of cases and with neutrophilic dermatosis (ND) in 20%. Pyoderma gangrenosum is usually a sporadic ND. A hereditary autosomal dominant syndromic kind of pyoderma gangrenosum, the PAPA syndrome, is linked to mutations in the CD2BP1/PSTPIP1 gene. We systematically screened this gene in French AA patients. RESULTS: One microsatellite (CCTG)n with 3 alleles was identified in the promoter. The longest form (CCTG)7 was significantly more frequent in AA patients than in French controls (P = 0.0154). We also found an association of the (CCTG)7 allele with CD in French patients (P = 0.0351). This association was not found in a sample of Indian patients. CONCLUSIONS: The CCTG repeat in the PSTPIP1 promoter may play a role in the pathogenesis of AA and of CD. Further investigations are required to demonstrate the possible modulation of gene expression by the (CCTG)n motif.

[From hereditary recurrent fevers to autoinflammatory syndromes: the contribution of genetics]. / Des fievres récurrentes héréditaires aux syndromes auto inflammatoires: les apports de la génétique.

Hereditary recurrent fevers are rare genetic diseases characterized by febrile periods of variable duration. Classically, four such diseases were recognized, namely familial Mediterranean fever (previously called periodic disease in France), the Muckle-Wells syndrome, Hibernian fever, and hyper IgD with recurrent fever. The discovery of culprit genes has led to an overhaul of this classification. Molecular diagnosis of these diseases, that are difficult to identify on clinical grounds alone, is now possible. Timely diagnosis is particularly important as, in the absence of treatment, there is a risk of secondary AA amyloidosis, which is fatal within 5 to 10 years. The discovery of underlying genetic mechanisms has also led to the development of new therapeutic approaches, which are currently being tested in clinical trials.

Biallelic mutations in the prokineticin-2 gene in two sporadic cases of Kallmann syndrome.

Kallmann syndrome is a developmental disease that combines hypogonadotropic hypogonadism and anosmia. Putative loss-of-function mutations in PROKR2 or PROK2, encoding prokineticin receptor-2 (a G protein-coupled receptor), and one of its ligands, prokineticin-2, respectively, have recently been reported in approximately 10% of Kallmann syndrome affected individuals. Notably, given PROKR2 mutations were found in the heterozygous, homozygous, or compound heterozygous state in patients, thus raising the question of a possible digenic inheritance of the disease in heterozygous patients. Indeed, one of these patients was also carrying a missense mutation in KAL1, the gene responsible for the X chromosome-linked form of Kallmann syndrome. Mutations in PROK2, however, have so far been found only in the heterozygous state. Here, we report on the identification of PROK2 biallelic mutations, that is, a missense mutation, p.R73C, and a frameshift mutation, c.163delA, in two out of 273 patients presenting as sporadic cases. We conclude that PROK2 mutations in the homozygous state account for a few cases of Kallmann syndrome. Moreover, since the same R73C mutation was previously reported in the heterozygous state, and because Prok2 knockout mice exhibit an abnormal phenotype only in the homozygous condition, we predict that patients carrying monoallelic mutations in PROK2 have another disease-causing mutation, presumably in still undiscovered Kallmann syndrome genes.

Analysis of the NOD2/CARD15 gene in patients affected with the aseptic abscesses syndrome with or without inflammatory bowel disease.

OBJECTIVES: NOD2/CARD15 is a susceptibility gene for Crohn's disease (CD). It is also involved, via different mutations, in the Blau syndrome. The syndrome of aseptic abscesses (AA) is characterized by visceral sterile collections of mature neutrophils that do not respond to antibiotics but regress quickly with corticosteroids. It is associated in two cases out of three with inflammatory bowel disease (IBD), and in particular with CD. We wanted to assess if changes on gene NOD2/CARD15 could contribute to the development of AA in patients with and without IBD. METHODS: Seventeen unrelated patients with AA from the French national register were genotyped for c.802C>T (p.Pro268Ser) and the three main CD associated variants, c.2104C>T (p.Arg702Trp), c.2722G>C (p.Gly908Arg) and c.3019_3020insC (p.Leu1007fsX1008), and 16 were screened for the 11 coding exons of NOD2/CARD15. RESULTS: The main variants associated with CD were found at a similar frequency in patients free of IBD and in those with CD. There was no significant difference in the main variants between patients with CD and those without IBD in our study and patients with CD and controls, respectively, from a large study of an ethnically similar population. No rare variant was found. A significant association between carriers of the silent variant c.1377 C>T and markers of severity of AA was observed. CONCLUSIONS: These results suggest that the emergence of AA is not closely related to gene NOD2/CARD15. NOD2/CARD15 and other susceptibility genes might enhance the expression of AA as the result of a combination of polymorphisms.

Novel FGFR1 sequence variants in Kallmann syndrome, and genetic evidence that the FGFR1c isoform is required in olfactory bulb and palate morphogenesis.

In a new cohort of 141 unrelated patients affected by Kallmann syndrome we identified FGFR1 sequence variants in 17 patients, all in the heterozygous state. The fifteen novel variants consist of 10 missense (p.N77K, p.C101F, p.R250W, p.G270D, p.P283R, p.S332C, p.H621R, p.S685F, p.I693F, p.R822C), two nonsense (p.E324X, p.R661X), a frameshift (p.S439fs), and two splice site (c.1081G>C and c.1977+1G>A) changes. However, the p.N77K and p.R822C changes were also found in two and one out of 150 healthy control individuals, respectively, and therefore, their pathogenic effect is questionable. Notably, three alterations (p.E324X, p.S332C, c.1081G>C) are located in the alternative exon 8B that codes for the FGFR1c isoform, thus indicating that this isoform plays a crucial role in the development of the olfactory system in man. Moreover, the presence of cleft palate in a patient carrying the p.E324X change shows that FGFR1c is important for palate morphogenesis too.

Kallmann syndrome: mutations in the genes encoding prokineticin-2 and prokineticin receptor-2.

Kallmann syndrome combines anosmia, related to defective olfactory bulb morphogenesis, and hypogonadism due to gonadotropin-releasing hormone deficiency. Loss-of-function mutations in KAL1 and FGFR1 underlie the X chromosome-linked form and an autosomal dominant form of the disease, respectively. Mutations in these genes, however, only account for approximately 20% of all Kallmann syndrome cases. In a cohort of 192 patients we took a candidate gene strategy and identified ten and four different point mutations in the genes encoding the G protein-coupled prokineticin receptor-2 (PROKR2) and one of its ligands, prokineticin-2 (PROK2), respectively. The mutations in PROK2 were detected in the heterozygous state, whereas PROKR2 mutations were found in the heterozygous, homozygous, or compound heterozygous state. In addition, one of the patients heterozygous for a PROKR2 mutation was also carrying a missense mutation in KAL1, thus indicating a possible digenic inheritance of the disease in this individual. These findings reveal that insufficient prokineticin-signaling through PROKR2 leads to abnormal development of the olfactory system and reproductive axis in man. They also shed new light on the complex genetic transmission of Kallmann syndrome.

Homozygous nonsense mutation in the FOXE3 gene as a cause of congenital primary aphakia in humans.

Congenital primary aphakia (CPA) is a rare developmental disorder characterized by the absence of lens, the development of which is normally induced during the 4th-5th wk of human embryogenesis. This original failure leads, in turn, to complete aplasia of the anterior segment of the eye, which is the diagnostic histological criterion for CPA. So far, the genetic basis for this human condition has remained unclear. Here, we present the analysis of a consanguineous family with three siblings who had bilateral aphakia, microphthalmia, and complete agenesis of the ocular anterior segment. We show that a null mutation in the FOXE3 gene segregates and, in the homozygous state, produces the mutant phenotype in this family. Therefore, this study identifies--to our knowledge, for the first time--a causative gene for CPA in humans. Furthermore, it indicates a possible critical role for FOXE3 very early in the lens developmental program, perhaps earlier than any role recognized elsewhere for this gene.