Challenging the traditional approach for interpreting genetic variants: Lessons from Fabry disease.

Fabry disease (FD) is an X-linked genetic disease due to pathogenic variants in GLA. The phenotype varies depending on the GLA variant, alpha-galactosidase residual activity, patient's age and gender and, for females, X chromosome inactivation. Over 1000 variants have been identified, many through screening protocols more susceptible to disclose non-pathogenic variants or variants of unknown significance (VUS). This, together with the non-specificity of some FD symptoms, challenges physicians attempting to interpret GLA variants. The traditional way to interpreting pathogenicity is based on a combined approach using allele frequencies, genomic databases, global and disease-specific clinical databases, and in silico tools proposed by the American College of Medical Genetics and Genomics. Here, a panel of FD specialists convened to study how expertise may compare with the traditional approach. Several GLA VUS, highly controversial in the literature (p.Ser126Gly, p.Ala143Thr, p.Asp313Tyr), were re-analyzed through reviews of patients' charts. The same was done for pathogenic GLA variants with some specificities. Our data suggest that input of geneticists and physicians with wide expertise in disease phenotypes, prevalence, inheritance, biomarkers, alleles frequencies, disease-specific databases, and literature greatly contribute to a more accurate interpretation of the pathogenicity of variants, bringing a significant additional value over the traditional approach.

Cornea verticillata and acroparesthesia efficiently discriminate clusters of severity in Fabry disease.

BACKGROUD: Fabry disease (OMIM #301 500), the most prevalent lysosomal storage disease, is caused by enzymatic defects in alpha-galactosidase A (GLA gene; Xq22.1). Fabry disease has historically been characterized by progressive renal failure, early stroke and hypertrophic cardiomyopathy, with a diminished life expectancy. A nonclassical phenotype has been described with an almost exclusive cardiac involvement. Specific therapies with enzyme substitution or chaperone molecules are now available depending on the mutation carried. Numerous clinical and fundamental studies have been conducted without stratifying patients by phenotype or severity, despite different prognoses and possible different pathophysiologies. We aimed to identify a simple and clinically relevant way to classify and stratify patients according to their disease severity. METHODS: Based on data from the French Fabry Biobank and Registry (FFABRY; n = 104; 54 males), we applied unsupervised multivariate statistics to determine clusters of patients and identify clinical criteria that would allow an effective classification of adult patients. Thanks to these criteria and empirical clinical considerations we secondly elaborate a new score that allow the severity stratification of patients. RESULTS: We observed that the absence of acroparesthesia or cornea verticillata is sufficient to classify males as having the nonclassical phenotype. We did not identify criteria that significantly cluster female patients. The classical phenotype was associated with a higher risk of severe renal (HR = 35.1; p <10-3) and cardiac events (HR = 4.8; p = 0.008) and a trend toward a higher risk of severe neurological events (HR = 7.7; p = 0.08) compared to nonclassical males. Our simple, rapid and clinically-relevant FFABRY score gave concordant results with the validated MSSI. CONCLUSION: Acroparesthesia and cornea verticillata are simple clinical criteria that efficiently stratify Fabry patients, defining 3 different groups: females and males with nonclassical and classical phenotypes of significantly different severity. The FFABRY score allows severity stratification of Fabry patients.

Treatment needs and expectations for Fabry disease in France: development of a new Patient Needs Questionnaire.

BACKGROUND: Fabry disease (FD) is a rare, X-linked, inherited lysosomal disease caused by absent or reduced α-galactosidase A activity. Due to the heterogeneity of disease presentation and progression, generic patient-reported outcome (PRO) tools do not provide accurate insight into patients' daily lives and impact of disease specific treatments. Also, the French National Health Authority, (HAS) actively encourages a patient-centric approach to improve the quality of care throughout the patient journey. In response to this initiative, we aimed to develop and validate a specific, self-reported, Patient Needs Questionnaire for people living with Fabry disease to appraise patient needs and expectations towards their treatment (PNQ Fabry). This endeavour was led with the help of French patient associations (APMF & VML) and dedicated expert centres. PNQ Fabry was developed according to the FDA/EMA methodologies and best practices for the development of PRO tools in rare diseases. Our approach comprised of three steps, as follows: concept elicitation and item generation, item reduction, and final validation of the questionnaire through a two-stage survey. RESULTS: Intrinsic and extrinsic reliability was established, using a validated benchmark questionnaire. With the invaluable help of patient associations, we recruited a satisfactory population in this rare disease setting, to ensure robust participation to validate our PNQ (final number of questionnaires: 76). At the end of the process, a 26-item patient-reported questionnaire was obtained with excellent psychometric properties, exhibiting very satisfactory measurement outcomes for reliability and validity. The results of this initiative demonstrate that the PNQ Fabry is accurate, suitable and tailored to FD patients, as it addresses themes identified during patient interviews, that were further validated through statistical analyses of quantitative surveys. An ongoing phase IV study is using this tool. CONCLUSION: We believe the PNQ Fabry will be a reliable and insightful tool in clinical practice, to improve patient management in FD.

Deep characterization of the anti-drug antibodies developed in Fabry disease patients, a prospective analysis from the French multicenter cohort FFABRY.

BACKGROUND: Fabry disease (OMIM #301500) is an X-linked disorder caused by alpha-galactosidase A deficiency with two major clinical phenotypes: classic and non-classic of different prognosis. From 2001, enzyme replacement therapies (ERT) have been available. We aimed to determine the epidemiology and the functional characteristics of anti-drug antibodies. Patients from the French multicenter cohort FFABRY (n = 103 patients, 53 males) were prospectively screened for total anti-agalsidase IgG and IgG subclasses with a home-made enzyme-linked immunosorbent assay (ELISA), enzyme-inhibition assessed with neutralization assays and lysoGb3 plasma levels, and compared for clinical outcomes. RESULTS: Among the patients exposed to agalsidase, 40% of men (n = 18/45) and 8% of women (n = 2/25) had antibodies with a complete cross-reactivity towards both ERTs. Antibodies developed preferentially in men with non-missense GLA mutations (relative risk 2.88, p = 0.006) and classic phenotype (58.6% (17/29) vs 6.7% (1/16), p = 0.0005). Specific anti-agalsidase IgG1 were the most frequently observed (16/18 men), but the highest concentrations were observed for IgG4 (median 1.89 µg/ml, interquartile range (IQR) [0.41-12.24]). In the men exposed to agalsidase, inhibition was correlated with the total IgG titer (r = 0.67, p < 0.0001), especially IgG4 (r = 0.75, p = 0.0005) and IgG2 (r = 0.72, p = 0.001). Inhibition was confirmed intracellularly in Fabry patient leucocytes cultured with IgG-positive versus negative serum (median: 42.0 vs 75.6%, p = 0.04), which was correlated with IgG2 (r = 0.67, p = 0.017, n = 12) and IgG4 levels (r = 0.59, p = 0.041, n = 12). Plasma LysoGb3 levels were correlated with total IgG (r = 0.66, p = 0.001), IgG2 (r = 0.72, p = 0.004), IgG4 (r = 0.58, p = 0.03) and IgG1 (r = 0.55, p = 0.04) titers. Within the classic group, no clinical difference was observed but lysoGb3 levels were higher in antibody-positive patients (median 33.2 ng/ml [IQR 20.6-55.6] vs 12.5 [10.1-24.0], p = 0.005). CONCLUSION: Anti-agalsidase antibodies preferentially develop in the severe classic Fabry phenotype. They are frequently associated with enzyme inhibition and higher lysoGb3 levels. As such, they could be considered as a hallmark of severity associated with the classic phenotype. The distinction of the clinical phenotypes should now be mandatory in studies dealing with Fabry disease and its current and future therapies.

Regressive pyridoxine-induced sensory neuronopathy in a patient with homocystinuria.

Pyridoxine (vitamin B6) is an essential vitamin playing a crucial role in amino acid metabolism. Pyridoxine is used for isoniazid side-effects prevention, pyridoxine-dependent epilepsy treatment and cystathionine beta-synthase deficiency (homocystinuria) treatment. However, vitamin B6 hypervitaminosis is neurotoxic and may provoke a progressive sensory neuronopathy (sensory ganglionopathy), usually when daily uptake is above 50 mg. We describe the case of a 30-year-old patient with homocystinuria who was treated with pyridoxine 1250-1750 mg/day for 20 years and developed progressive sensory neuropathy with ataxia and impaired sensation in the extremities. Electrodiagnostic testing demonstrated non-length-dependent abnormalities of sensory nerve potentials, and sensory ganglionopathy was diagnosed. Pyridoxine dosage was reduced to 500 mg/day, resulting in the disappearance of sensory symptoms and ataxia, and the normalisation of sensory nerve potentials. Our case indicates that pyridoxine-induced sensory ganglionopathy may be reversible, even after prolonged ingestion of high doses of vitamin B6 for more than 20 years.

Respiratory Complications Lead to the Diagnosis of Chronic Granulomatous Disease in Two Adult Patients.

Chronic granulomatous disease (CGD) is a primary immunodeficiency associated to multiple life-threatening bacterial and fungal infections, beginning in childhood. There are rare cases of diagnosis in adulthood. We describe here two cases of late diagnosis in adults: a 45-year-old woman and 59-year-old-man. CGD diagnosis should be considered in adult patients with unexplained infectious diseases with tissue granuloma.

[Recurrent facial palsy, primary Gougerot-Sjögren's syndrome and vitamin B12 deficiency]. / Paralysie faciale récidivante, syndrome de Gougerot-Sjögren primitif et carence en vitamine B12.

INTRODUCTION: Differing cranial nerve involvement has been reported in the context of Gougerot-Sjögren's syndrome. Involvement of the V, III and VII nerves has been reported, the most characteristic being nerve V, notably its lower branch. Rare, well documented, cases of facial palsy have also been described. OBSERVATION: Recurrent facial palsy in a 40 year-old woman revealed a primary Sjögren's syndrome and vitamin B12 deficiency. DISCUSSION: The onset of facial palsy has been linked with Gougerot-Sjögren's syndrome. The contribution of vitamin B12 deficiency is discussed.

Prognostic factors of hematological recovery in life-threatening nonchemotherapy drug-induced agranulocytosis. A study of 91 patients from a single center.

OBJECTIVES: We studied clinical factors that may influence the duration of hematological recovery to reach neutrophil counts and thus, indirectly, the prognosis in patients with life-threatening drug-induced agranulocytosis (DIA). METHODS: Using univariate and multivariate analyses with Cox's proportional hazard models, we determined the prognostic factors for hematological recovery, defined as neutrophil counts>0.5 and>1.5.10(9)/L, in 91 patients with established life-threatening DIA. RESULTS: Multivariable analysis showed that neutrophil count<0.1.10(9)/L (at diagnosis) and infection profile: severe infections or septic shock, adversely influenced the neutrophil recovery (for the two neutrophil levels). Hematopoietic growth factors were significantly associated with rapid hematological recovery (for the two neutrophil levels). Documented microbial infections and antiplatelet DIA were also associated with rapid hematological recovery (for a neutrophil count>1.5.10(9)/L). CONCLUSION: Our findings demonstrate that in life-threatening DIA, hematological recovery is mainly dependent of the neutrophil level, the type of infections and the utilization of hematopoietic growth factors.

Life-threatening idiosyncratic drug-induced agranulocytosis in elderly patients.

Agranulocytosis is a life-threatening disorder in any age, but particularly so in elderly patients who are receiving, on average, a larger number of drugs than younger patients. Drug-induced agranulocytosis still remains a rare event, with an annual incidence rate of approximately 3-12 cases per million population. This disorder frequently occurs as an adverse reaction to drugs, particularly antibacterials, antiplatelet agents, antithyroid drugs, antipsychotics or antiepileptic drugs, and NSAIDs. Although patients experiencing drug-induced agranulocytosis may initially be asymptomatic, the severity of the neutropenia usually translates into the onset of severe sepsis that requires intravenous broad-spectrum antibacterial therapy. In this setting, haematopoietic growth factors have been shown to shorten the duration of neutropenia. Thus, with appropriate management, the mortality rate of idiosyncratic drug-induced agranulocytosis is now 5-10%. However, given the increased life expectancy and subsequent longer exposure to drugs, as well as the development of new agents, physicians should be aware of this complication and its management.

[Hepatitis C and tricholeukocyte leukemia: a fortuitous association? A case report]. / Hépatite virale C et leucémie à tricholeucocytes: association fortuite? Une observation.

The association of hepatitis C and certain hemotological diseases (non-Hodgkin B-cell lymphoma, villous splenic lymphoma.) is a debated question which remains open due to discordant epidemiological data. We report the case of a new patient with chronic hepatitis C and tricholeukocyte leukemia.

Oral chemotherapy in colorectal cancer treatment: review of the literature.

Recent advances in anticancer treatment have focused on the development of oral anticancer agents with the intention of improving the patients' quality of life as well as providing therapeutic alternatives to intravenous chemotherapy. Until agents such as oxaliplatin and irinotecan became available, the treatment of colorectal cancer, one the most common cancers diagnosed in industralized countries, was mainly based on 5-fluorouracil modulation. The overwhelming majority of these new drugs are pyrimidine analogues intended to replace intravenous treatment or to make the therapy more acceptable to the patients. In this article, the use of oral chemotherapy, alone or in combination with radiotherapy, in colorectal cancer is reviewed and updated. The rationale for using oral compounds is discussed and newer agents, such as oral camptothecin analogues and antiangiogenic agents, are presented with the results of their clinical and preclinical developments.