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Federated learning for the pathogenicity annotation of genetic variants in multi-site clinical settings.

MOTIVATION: Rare diseases collectively affect 5% of the population. However, fewer than 50% of rare disease patients receive a molecular diagnosis after whole genome sequencing. Supervised machine learning is a valuable approach for the pathogenicity scoring of human genetic variants. However, existing methods are often trained on curated but limited central repositories, resulting in poor accuracy when tested on external cohorts. Yet, large collections of variants generated at hospitals and research institutions remain inaccessible to machine-learning purposes because of privacy and legal constraints. Federated learning (FL) algorithms have been recently developed enabling institutions to collaboratively train models without sharing their local datasets. RESULTS: Here, we present a proof-of-concept study evaluating the effectiveness of FL for the clinical classification of genetic variants. A comprehensive array of diverse FL strategies was assessed for coding and non-coding Single Nucleotide Variants as well as Copy Number Variants. Our results showed that federated models generally achieved comparable or superior performance to traditional centralized learning. In addition, federated models reached a robust generalization to independent sets with smaller data fractions as compared to their centralized model counterparts. Our findings support the adoption of FL to establish secure multi-institutional collaborations in human variant interpretation. AVAILABILITY AND IMPLEMENTATION: All source code required to reproduce the results presented in this article, implemented in Python, is available under the GNU General Public License v3 at https://github.com/RausellLab/FedLearnVar.

Humans↗

Enzymic properties of different types of human erythrocyte glucose-6-phosphate dehydrogenase, with characterization of two new genetic variants.

Enzymic properties have been compared in the following five genetic variants of glucose-6-phosphate dehydrogenase from human erythrocytes: the two common variants with normal activity, A and B; the common variant associated with enzyme deficiency, A-; and two new rare variants, "Ijebu-Ode" and "Ita-Bale."The maximal velocity of the enzyme reaction (V(max)) increases steadily with pH over the entire range explored (from pH 5.5 to 9.5) for all enzyme variants when buffers are used that show no specific ion effects on enzyme activity. Small differences are found among the variants in the pH range 7.5-8.2, where A and B show a "peak and trough," while A-, "Ijebu-Ode," and "Ita-Bale" exhibit a plateau. When the effects of reagents that bind to sulphydryl groups are compared, iodoacetate, bromoacetate, and iodoacetamide are weak inhibitors, while N-ethylmaleimide (NEM) and hydroxymercuribenzoate (HMB) are potent inhibitors. The last two reagents have differential inhibitory action on different variants; one of these, "Ijebu-Ode," is strikingly resistant to HMB and totally resistant to NEM (up to 3 mmoles/liter). The enzyme inactivation as a function of temperature exhibits distinctive profiles for all variants examined. BOTH OF THE NEW VARIANTS DESCRIBED DIFFER SIGNIFICANTLY FROM THE NORMAL B TYPE IN SEVERAL RESPECTS: "Ijebu-Ode" in electrophoretic mobility, thermostability, dependence of V(max) on pH, and resistance to sulphydryl group reagents; "Ita-Bale" in electrophoretic mobility, Michaelis constant (K(m)) for glucose-6-phosphate, and dependence of V(max) on pH. When these data are compared with those available in the literature, both variants are different from all those previously described. The estimated frequencies of the corresponding genes in western Nigeria are between 0.0005 and 0.0025 for "Ijebu-Ode" and less than 0.0005 for "Ita-Bale". The A- variant, compared to A, has a distinctly higher K(m) for 2-deoxyglucose-6-phosphate and is more inhibited by very low concentrations of HMB. These are the first observed differences in kinetic properties between A and A-.

Chemical Phenomena↗

Genetic variants of the T-cell immunoglobulin mucin 1 but not the T-cell immunoglobulin mucin 3 gene are associated with asthma in an African American population.

BACKGROUND: The T-cell immunoglobulin mucin ( TIM ) proteins and their genetic variants have been suggested to play a role in regulating allergic diseases. OBJECTIVE: Genetic association of the sequence variants for TIM-1 and TIM-3 genes with asthma in an African American population was investigated. METHODS: Both case-control and family-based association analyses were performed for a total of 7 polymorphisms, including 3 single nucleotide polymorphism (SNPs) and 1 insertion/deletion polymorphism in the TIM-1 and 3 SNPs in the TIM-3 genes. The exposure to hepatitis A virus as judged by seropositivity was also examined. RESULTS: In the case-control design, the frequencies of the TT genotype for SNP rs2277025 and the homozygous deletion variant (157delMTTTVP) in the fourth exon of the TIM-1 gene were higher among patients with patients with asthma compared with the controls (odds ratio [OR], 2.779, P = .016; and OR, 3.09, P = .022, respectively). This association was substantiated by haplotype analysis of these and 2 additional SNPs (OR, 2.48; P = .004), and also by family-based tests for the allele and haplotype carrying 157delMTTTVP (P = .009 and P = .048, respectively). Furthermore, this association seems to exist even in the hepatitis A virus-seronegative subjects in our data. None of the 3 variants in TIM-3 genes yielded significant association with either asthma or asthma-related phenotypes. CONCLUSION: Our findings suggest that the genetic variants of the TIM-1 but not the TIM-3 gene contribute to asthma susceptibility in this African-American population.

Adult↗

Genetic variants of collagen III and abdominal aortic aneurysm.

Collagens provide the tensile strength of the aortic wall. Variations in collagen structure are recognised in Ehlers Danlos syndrome type IV and could also be associated with a predisposition to aortic aneurysm. The frequency of some minor genetic variants of type III collagen, present in the normal population, can be detected by restriction enzyme digestion of genomic DNA from peripheral leucocytes. The frequency of a minor collagen type III allele demonstrated with the restriction enzyme Ava II was compared in patients with abdominal aortic aneurysm (n = 70) and aortoiliac stenosis (n = 47). The frequency of the minor allele was significantly higher in aneurysm patients (0.30) compared with patients with aortoiliac stenosis (0.17), p less than 0.05. The presence of the minor allele was associated with a less elastic aneurysm wall (median pressure strain elastic modulus 4575, n = 7), compared with patients homozygous for the common allele (median pressure strain elastic modulus 1990, n = 6), p less than 0.05. These results indicate that genetic variants of type III collagen may influence the extensile properties of the aortic wall and that mutations in the type III collagen gene may be associated with aortic aneurysms.

Aged↗

Dopamine D2 receptor and N-methyl-D-aspartate receptor 2B subunit genetic variants and intelligence.

The dopaminergic and glutamate systems have been implicated in cognitive function. We tested the associations between the dopamine D2 receptor (DRD2) and N-methyl-D-aspartate receptor 2B subunit (GRIN2B) gene variants and intelligence quotient (IQ). Subjects with the DRD2 A1/A1 genotype had a significantly higher mean performance IQ than A2/A2 carriers, while no significant differences in IQ scores were determined for the three GRIN2B genotype groups. These results suggest that genetic variants of the DRD2 gene may play a role in cognitive function. Considering the major role played by the dopaminergic system in general cognitive function, genetic variants of the dopamine receptors and those involved in metabolism and modulation of reuptake should be tested to improve gene-based prediction of general cognitive function.

Adult↗

A new genetic variant Z2 in the Pi system of horses.

A new genetic variant in the horse Pi system, designated Z2, was reported in Polish Arabs by using two-dimensional agarose polyacrylamide gel electrophoresis. The frequencies of Pi alleles F, G, L, L2, N, S, U, W, Z and Z2 were found to be 0.036, 0.005, 0.171, 0.013, 0.008, 0.237, 0.416, 0.003, 0.107 and 0.004 respectively.

Animals↗

Impact of GPCRs in clinical medicine: monogenic diseases, genetic variants and drug targets.

By virtue of their large number, widespread distribution and important roles in cell physiology and biochemistry, G-protein-coupled receptors (GPCR) play multiple important roles in clinical medicine. Here, we focus on 3 areas that subsume much of the recent work in this aspect of GPCR biology: (1) monogenic diseases of GPCR; (2) genetic variants of GPCR; and (3) clinically useful pharmacological agonists and antagonists of GPCR. Diseases involving mutations of GPCR are rare, occurring in <1/1000 people, but disorders in which antibodies are directed against GPCR are more common. Genetic variants, especially single nucleotide polymorphisms (SNPs), show substantial heterogeneity in frequency among different GPCRs but have not been evaluated for some GPCR. Many therapeutic agonists and antagonists target GPCR and show inter-subject variability in terms of efficacy and toxicity. For most of those agents, it remains an open question whether genetic variation in primary sequence of the GPCR is an important contributor to such inter-subject variability, although this is an active area of investigation.

Alleles↗

Genetic variants of the renin-angiotensin system, diabetic nephropathy and hypertension.

Recent studies have suggested an association between a deletion (D) variant of the angiotensin-converting-enzyme (ACE) gene and diabetic nephropathy. However, this finding has not been confirmed by all investigators. Furthermore, an M235T variant of the angiotensinogen (AGT) gene has been associated with hypertension, an important risk factor for the development and progression of diabetic nephropathy. The objective of our study was therefore to examine the relationship between these genetic variants of the renin-angiotensin system and diabetic nephropathy and hypertension, respectively, in a large (n = 661) group of Caucasian patients with insulin-dependent (n = 360) or non-insulin-dependent (n = 301) diabetes mellitus. The study had a power of 0.8 to detect a doubling of risk of nephropathy or hypertension in patients with the ACE-DD or AGT-235TT genotype, respectively. Allelic frequencies of the ACE-D and AGT-235T alleles were similar between patients with and without nephropathy in either type of diabetes, and accordingly, there was no significant association between diabetic nephropathy and the ACE or AGT genotype. Likewise, there was no significant association between the ACE or AGT genotype and hypertension. Thus, our data, in this large and ethnically homogeneous group of patients, do not support the hypothesis that these genetic variants of the renin-angiotensin system are strongly associated with either nephropathy or hypertension in patients with insulin-dependent or non-insulin-dependent diabetes mellitus. These genetic markers are therefore unlikely to serve as clinically useful predictors of either nephropathy or hypertension in Caucasian patients with diabetes.

Adult↗

Clusters of 43-kDa protein are absent from genetic variants of C2 muscle cells with reduced acetylcholine receptor expression.

Genetic variants of the C2 muscle cell line were used to investigate the relation between acetylcholine receptor (AChR) clustering and clustering of the 43-kDa protein. Two variants that express severely reduced amounts of the alpha subunit of the AChR and consequently lack AChR clusters were found also to lack clusters of the 43-kDa protein. The amount of 43-kDa protein in the variants measured by immunoassay was reduced to about one-third the levels found in wild-type cells. The beta subunit of the AChR was reduced to a similar extent. Northern blot analysis showed that neither the 43-kDa protein mRNA nor the beta subunit mRNA was reduced in the variants. Taken together, these results suggest that the amounts of beta subunit and 43-kDa protein may be regulated coordinately by a post-transcriptional mechanism.

Animals↗

The functional defect of factor VIII Leiden, a genetic variant of coagulation factor VIII.

Factor VIII Leiden is a genetic variant of coagulation factor VIII which has been detected in the plasma of a patient with mild haemophilia A. In this patient's plasma factor VIII procoagulant antigen was in 5-fold excess over factor VIII procoagulant activity, indicating the presence of an abnormal factor VIII molecule. The variant factor VIII was isolated from the patient's plasma, and its functional properties were studied in a factor X-activating system consisting of purified components. The isolated factor VIII Leiden was normally activated by factor Xa and by thrombin, but the activity of the factor VIIIa was about 3% of normal. The defect of factor VIIIa Leiden was studied by comparison with normal factor VIIIa in kinetic experiments of factor Xa formation. The results support the hypothesis that factor VIIIa Leiden has a reduced affinity for phospholipid-bound factor IXa in the intrinsic factor X-activating complex.

Calcium↗

Specific genetic variants of Actinobacillus actinomycetemcomitans correlate with disease and health in a regional population of families with localized juvenile periodontitis.

A geographically homogeneous population of 83 subjects, from 21 families with localized juvenile periodontitis (LJP), and 35 healthy control subjects was monitored, over a 5-year period, for the presence of the periodontal pathogen Actinobacillus actinomycetemcomitans. Restriction fragment length polymorphism (RFLP) analysis was used to monitor the distribution of genetic variants of this bacterium in LJP-susceptible subjects that converted from a healthy to a diseased periodontal status. A. actinomycetemcomitans was cultured from 57% of the LJP family members accessioned into the study. Nine of 36 LJP-susceptible subjects, in seven families, developed signs of periodontal destruction. All but one of these conversion subjects harbored A. actinomycetemcomitans. Bacterial variants representative of a single RFLP group (II) showed the strongest correlation with conversion (P < 0.002). Six of nine conversion subjects were infected with A. actinomycetemcomitans from this group. RFLP group II variants also prevailed in 8 of 22 probands but were absent in the 35 healthy control subjects. In contrast to the selective distribution of group II variants is diseased individuals, variants belonging to RFLP groups XIII and XIV were found exclusively in the control subjects. Thus, the use of RFLP to type clinical isolates of A. actinomycetemcomitans has resulted in the identification of genetic variants that predominate in LJP and health. These results indicate that studies concerned with the pathogenicity of this bacterium in LJP should be focused on the group II variants.

Adult↗

Identification of a new genetic variant of bovine beta-casein using reversed-phase high-performance liquid chromatography and mass spectrometric analysis.

Various components of the beta-casein fraction from bovine milk were separated by preparative reversed-phase high-performance liquid chromatography (RP-HPLC). They included the genetic variants beta A1, beta A2, beta A3, and an unknown component previously denoted beta X [S. Visser et al., J. Chromatogr. 548 (1991) 361-370]. Tryptic digests of these components were compared by RP-HPLC and most peaks were analysed by mass spectrometry (MS). The tryptic map of beta X was closest to that of beta A1, but with a few mutually different peak components. Electrospray ionisation MS revealed that in the beta X map these components had relative molecular masses of 16 higher than the corresponding ones in the beta A1 map. The main differential peaks represented the 114-169 fragments of beta A1 and beta X, respectively, which were both purified and then cleaved with cyanogen bromide. In the resulting mixtures, each of which contained three fragments, the corresponding peptides representing the 145-156 sequence showed the 16 relative molecular mass difference. In beta X this sequence contained a Leu residue at position 152 instead of the Pro-152 in beta A1, as established by fast-atom bombardment MS-MS. The Leu could be discriminated from an Ile residue by the presence of a side-chain-specific, D-type fragment ion in the MS-MS spectrum of the beta X CNBr peptide. The sequence of the two homologous 145-156 fragments was confirmed by regular amino acid sequence analysis. In accordance with internationally accepted guidelines for the nomenclature of milk proteins, the new genetic variant has been named beta-casein F-5P.

Amino Acid Sequence↗

Association of vitamin D receptor genetic variants with susceptibility to asthma and atopy.

Genome scans for asthma have identified suggestive or significant linkages on 17 different chromosomes, including chromosome 12, region q13-23, housing the vitamin D receptor (VDR) gene. Through interaction with VDR, 1,25-dihydroxyvitamin D3 mediates numerous biological activities, such as regulation of helper T-cell development and subsequent cytokine secretion profiles. Variants of the VDR have been found to be associated with immune-mediated diseases that are characterized by an imbalance in helper T-cell development, such as Crohn's disease and tuberculosis. The VDR, hence, is a good candidate to be investigated for association with asthma, which is characterized by enhanced helper T-cell type 2 activity. Here, we examined VDR genetic variants in an asthma family-based cohort from Quebec. We report six variants to be strongly associated with asthma and four with atopy (0.0005 < or = p < or = 0.05). Analysis of the linkage disequilibrium pattern and haplotypes also revealed significant association with both phenotypes (0.0004 < or = p < or = 0.01). The findings have been replicated by another research team in a second but not in a third cohort. These results identify VDR variants as genetic risk factors for asthma/atopy and implicate a non-human leukocyte antigen immunoregulatory molecule in the pathogenesis of asthma and atopy.

Adolescent↗

Haplotype analysis of endothelial nitric oxide synthase (NOS3) genetic variants and tardive dyskinesia in patients with schizophrenia.

OBJECTIVES: Several studies have indicated the involvement of nitric oxide (NO) in the pathogenesis of tardive dyskinesia (TD), an incapacitating adverse movement disorder associated with long-term antipsychotic treatment. In human brain, the NO could be generated by endothelial nitric oxide synthase (NOS3). In this study, we studied whether the genetic variants in human NOS3 gene is associated with TD in patients with schizophrenia. METHODS: Two hundred and eighty-two chronic inpatients with schizophrenia treated with typical antipsychotics were recruited in this study. The patients were further grouped by the presence of TD or not according to the Research and Diagnostic Criteria for TD. The genetic variants in the NOS3 gene investigated in this study were -786T > C in the promotor region, 27-bp variable number of tandem repeats (27-bp VNTR) in intron 4, and Glu298Asp in exon 7. The frequencies of genotypes, alleles and haplotypes of the three markers were compared between the TD (n = 153) and non-TD (n = 129) groups. RESULTS: There were no significant associations between the genotypes and alleles of the three markers and TD. However, in the haplotype-based case-control analysis, the frequency of haplotype T-4b-Glu was significantly higher in non-TD than in TD group (TD vs. non-TD = 72.7% vs. 81.0%, permutation P value = 0.021, OR = 0.648, 95% CI = 0.432-0.973). CONCLUSIONS: We found that the haplotype T-4b-Glu represents a protective haplotype against TD after long-term antipsychotic treatment. This finding suggests that human NOS3 gene may be involved in the pathogenesis of TD.

Adult↗

Association study of functional genetic variants of innate immunity related genes in celiac disease.

BACKGROUND: Recent evidence suggest that the innate immune system is implicated in the early events of celiac disease (CD) pathogenesis. In this work for the first time we have assessed the relevance of different proinflammatory mediators typically related to innate immunity in CD predisposition. METHODS: We performed a familial study in which 105 celiac families characterized by the presence of an affected child with CD were genotyped for functional polymorphisms located at regulatory regions of IL-1alpha, IL-1beta, IL-1RN, IL-18, RANTES and MCP-1 genes. Familial data was analysed with a transmission disequilibrium test (TDT) that revealed no statistically significant differences in the transmission pattern of the different genetic markers considered. RESULTS: The TDT analysis for IL-1alpha, IL-1beta, IL-1RN, IL-18, and MCP-1 genes genetic variants did not reveal biased transmission to the affected offspring. Only a borderline association of RANTES promoter genetic variants with CD predisposition was observed. CONCLUSION: Our results suggest that the analysed polymorphisms of IL-1alpha, IL-1beta, IL-1RN, IL-18, RANTES and MCP-1 genes do not seem to play a major role in CD genetic predisposition in our population.

Celiac Disease↗

The effect of RANTES chemokine genetic variants on early HIV-1 plasma RNA among African American injection drug users.

HIV-1 plasma RNA is a prognostic indicator of HIV-1, and increased levels of HIV-1 plasma RNA are associated with rapid progression to AIDS. Because chemokines and chemokine receptors are involved in the binding and entry of HIV-1, possible effects of host genetics on viral RNA levels should be visible in early infection. HIV-1 plasma RNA was measured within 2 years of seroconversion in 198 seroincident injection drug users followed in the AIDS Link to Intravenous Experience cohort. Genetic variants were identified in the chemokine receptors (CCR2, CCR5, and CCR5 promoter) and the chemokine RANTES using TaqMan and restriction fragment length polymorphism assays. Linear regression of RANTES haplotypes on early HIV-1 plasma RNA identified individuals homozygous for the RANTES R1 haplotype as having a lower viral load by almost one-half log10 unit compared with those bearing non-RANTES R1 haplotypes (-0.43, 95% confidence interval: -0.74, -0.12). Genetic variants in RANTES may downregulate RANTES gene expression and increase early HIV-1 plasma RNA. Because RANTES is a critical chemokine and competitively inhibits HIV-1 by binding to its receptor CCR5, treatment to enhance RANTES expression may assist in delaying the progression of AIDS by decreasing the initial viral load.

Acquired Immunodeficiency Syndrome↗

Sequence of caprine alpha s1-casein and characterization of those of its genetic variants which are synthesized at a high level, alpha s1-CnA, B and C.

The sequence of caprine alpha s1-casein (199 residues) was established. The peptide chain has the same length as, and shows a 88% degree of identity with, its bovine counterpart. With the ovine alpha s1-casein, the sequence of which was deduced from that of its mRNA, the degree of identity is 97%, counting as one difference a deletion of eight residues in the ovine protein. The differences between the three genetic variants associated with a high alpha s1-casein content in milk are simple substitutions. Variant alpha s1-CnA differs from variant alpha s1-CnB by two substitutions, 16 Leu (A)----Pro (B) and 77 Gln (A)----Glu (B), the latter inducing the appearance of a phosphate group on 75 Ser. Variant alpha s1-CnC differs from alpha s1-CnB by three substitutions, 8 His (B)----Ile (C), 100 Arg (B)----Lys (C) and 195 Thr (B)----Ala (C). The original type of caprine alpha s1-casein could be another hypothetical genetic variant, having the same electrophoretic mobility as alpha s1-CnB.

Amino Acid Sequence↗

The interaction between factor VIII clotting antigen and phospholipids in genetic variants of hemophilia and von Willebrand's disease.

The interaction of factor VIII with phospholipids was investigated in 11 patients with mild and moderate hemophilia A, 7 patients with von Willebrand's disease and in 10 healthy people as controls. The addition of phospholipid vesicles containing phosphatidylserine and phosphatidylethanolamine to normal plasma and that of patients with von Willebrand's disease resulted in the loss of almost two thirds of the factor VIII clotting antigen (VIII:CAg) measurable by IRMA. Defective interaction of phospholipids with VIII:CAg was noted in some genetic variants of mild and moderate hemophilia A. Thus four of the five families tested showed decreased binding of VIII:CAg to phospholipids. One of the families tested belonged to a genetic variant with much more VIII:CAg than VIII:C, and it was in members of this family that the binding capacity was most reduced. The most probable explanations for the defective interaction with phospholipids is that molecular defects of VIII:CAg result in either decreased binding to phospholipids or might lead to a stronger binding between VIII:CAg and the von Willebrand factor (VIIIR:Ag) in the factor VIII complex and thereby preventing the normal separation of the complex.

Adult↗