Publications by authors named "Giorgia Mandrile"

26 Publications

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[Management of Primary Hyperoxaluria Type 1 in Italy].

G Ital Nefrol 2021 Apr 14;38(2). Epub 2021 Apr 14.

Ospedale Infantile Regina Margherita, Torino, Italia.

Primary hyperoxaluria type 1 is a rare genetic disease; the onset of symptoms ranges from childhood to the sixth decade of life and the disease may go unrecognized for several years. There is an urgent need for drugs able to inhibit the liver production of oxalate and to prevent the disease progression; lumasiran, an innovative molecule based on RNAi interference, is one of the most promising drugs. A group of leading Italian experts on this disease met to respond to some unmet medical needs (early diagnosis, availability of genetic tests and dosage of plasma oxalate, timing of liver transplantation, need for etiologic treatment), based on the analysis of the main scientific evidence and their personal experience. Children showing the characteristic symptoms of the disease usually undergo a metabolic screening and obtain an early diagnosis, while the experience is very limited in adults and the diagnosis difficult. It is therefore essential to increase the knowledge around this disease and the importance of metabolic and genetic screening to define a checklist of shared clinical and laboratory criteria and to establish a multidisciplinary management of potential patients. Oxalate is the cause of the disease: it is crucial to reduce both oxaluria and oxalemia through appropriate therapeutic strategies, able to prevent and/or reduce renal and systemic complications of primary type 1 hyperoxaluria. Lumasiran allows to significantly reduce the levels of oxalate both in blood and in urine, halting the course of the disease and preventing serious renal and systemic complications, if the therapy is started at an early stage of the disease.
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April 2021

Combined liver kidney transplantation for primary hyperoxaluria type 1: Will there still be a future? Current transplantation strategies and monocentric experience.

Pediatr Transplant 2021 Mar 20:e14003. Epub 2021 Mar 20.

General Surgery 2U and Liver Transplant Unit, Department of Surgical Sciences, A.O.U. Città della Salute e della Scienza, Molinette Hospital, University of Torino, Torino, Italy.

Combined liver-kidney transplantation is a therapeutic option for children affected by type 1 primary hyperoxaluria. Persistently high plasma oxalate levels may lead to kidney graft failure. It is debated whether pre-emptive liver transplantation, followed by kidney transplantation, might be a better strategy to reduce kidney graft loss. Our experience of 6 pediatric combined liver-kidney transplants for primary hyperoxaluria type 1 in pediatric recipients was retrospectively analyzed. Plasma oxalate levels were monitored before and after transplantation. All the recipients were on hemodialysis at transplantation. Median [IQR] recipient's age at transplantation was 11 [1-14] years; in all cases, a compatible graft from a pediatric brain-dead donor aged 8 [2-16] years was used. In a median follow-up of 7 [2-19] years after combined liver-kidney transplantation, no child died and no liver graft failure was observed; three kidney grafts were lost, due to chronic rejection, primary non-function, and early renal oxalate accumulation. Liver and kidney graft survival remained stable at 1, 3, and 5 years, at 100% and 85%, respectively. Kidney graft loss was the major complication in our series. Risk is higher with very young, low-weight donors. The impact of treatment with glyoxalate pathway enzyme inhibitors treatment in children with advanced disease as well as of donor kidney preservation by ex vivo machine perfusion needs to be evaluated. At present, a case-by-case discussion is needed to establish an optimal treatment strategy.
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http://dx.doi.org/10.1111/petr.14003DOI Listing
March 2021

DLG4-related synaptopathy: a new rare brain disorder.

Genet Med 2021 Feb 17. Epub 2021 Feb 17.

Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.

Purpose: Postsynaptic density protein-95 (PSD-95), encoded by DLG4, regulates excitatory synaptic function in the brain. Here we present the clinical and genetic features of 53 patients (42 previously unpublished) with DLG4 variants.

Methods: The clinical and genetic information were collected through GeneMatcher collaboration. All the individuals were investigated by local clinicians and the gene variants were identified by clinical exome/genome sequencing.

Results: The clinical picture was predominated by early onset global developmental delay, intellectual disability, autism spectrum disorder, and attention deficit-hyperactivity disorder, all of which point to a brain disorder. Marfanoid habitus, which was previously suggested to be a characteristic feature of DLG4-related phenotypes, was found in only nine individuals and despite some overlapping features, a distinct facial dysmorphism could not be established. Of the 45 different DLG4 variants, 39 were predicted to lead to loss of protein function and the majority occurred de novo (four with unknown origin). The six missense variants identified were suggested to lead to structural or functional changes by protein modeling studies.

Conclusion: The present study shows that clinical manifestations associated with DLG4 overlap with those found in other neurodevelopmental disorders of synaptic dysfunction; thus, we designate this group of disorders as DLG4-related synaptopathy.
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http://dx.doi.org/10.1038/s41436-020-01075-9DOI Listing
February 2021

The ILE56 mutation on different genetic backgrounds of alanine:glyoxylate aminotransferase: Clinical features and biochemical characterization.

Mol Genet Metab 2020 Sep - Oct;131(1-2):171-180. Epub 2020 Aug 7.

Department of Experimental Medicine, University of Perugia, Perugia, Italy. Electronic address:

Primary Hyperoxaluria type I (PH1) is a rare disease caused by mutations in the AGXT gene encoding alanine:glyoxylate aminotransferase (AGT), a liver enzyme involved in the detoxification of glyoxylate, the failure of which results in accumulation of oxalate and kidney stones formation. The role of protein misfolding in the AGT deficit caused by most PH1-causing mutations is increasingly being recognized. In addition, the genetic background in which a mutation occurs is emerging as a critical risk factor for disease onset and/or severity. Based on these premises, in this study we have analyzed the clinical, biochemical and cellular effects of the p.Ile56Asn mutation, recently described in a PH1 patient, as a function of the residue at position 11, a hot-spot for both polymorphic (p.Pro11Leu) and pathogenic (p.Pro11Arg) mutations. We have found that the p.Ile56Asn mutation induces a structural defect mostly related to the apo-form of AGT. The effects are more pronounced when the substitution of Ile56 is combined with the p.Pro11Leu and, at higher degree, the p.Pro11Arg mutation. As compared with the non-pathogenic forms, AGT variants display reduced expression and activity in mammalian cells. Vitamin B6, a currently approved treatment for PH1, can overcome the effects of the p.Ile56Asn mutation only when it is associated with Pro at position 11. Our results provide a first proof that the genetic background influences the effects of PH1-causing mutations and the responsiveness to treatment and suggest that molecular and cellular studies can integrate clinical data to identify the best therapeutic strategy for PH1 patients.
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http://dx.doi.org/10.1016/j.ymgme.2020.07.012DOI Listing
August 2020

Mapping and phasing of structural variation in patient genomes using nanopore sequencing.

Nat Commun 2017 11 6;8(1):1326. Epub 2017 Nov 6.

Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, 3584 CG, Utrecht, The Netherlands.

Despite improvements in genomics technology, the detection of structural variants (SVs) from short-read sequencing still poses challenges, particularly for complex variation. Here we analyse the genomes of two patients with congenital abnormalities using the MinION nanopore sequencer and a novel computational pipeline-NanoSV. We demonstrate that nanopore long reads are superior to short reads with regard to detection of de novo chromothripsis rearrangements. The long reads also enable efficient phasing of genetic variations, which we leveraged to determine the parental origin of all de novo chromothripsis breakpoints and to resolve the structure of these complex rearrangements. Additionally, genome-wide surveillance of inherited SVs reveals novel variants, missed in short-read data sets, a large proportion of which are retrotransposon insertions. We provide a first exploration of patient genome sequencing with a nanopore sequencer and demonstrate the value of long-read sequencing in mapping and phasing of SVs for both clinical and research applications.
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http://dx.doi.org/10.1038/s41467-017-01343-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5673902PMC
November 2017

Defining the diverse spectrum of inversions, complex structural variation, and chromothripsis in the morbid human genome.

Genome Biol 2017 03 6;18(1):36. Epub 2017 Mar 6.

Molecular Neurogenetics Unit and Psychiatric and Neurodevelopmental Genetics Unit, Center for Genomic Medicine, and Department of Neurology, Massachusetts General Hospital, Boston, MA, 02114, USA.

Background: Structural variation (SV) influences genome organization and contributes to human disease. However, the complete mutational spectrum of SV has not been routinely captured in disease association studies.

Results: We sequenced 689 participants with autism spectrum disorder (ASD) and other developmental abnormalities to construct a genome-wide map of large SV. Using long-insert jumping libraries at 105X mean physical coverage and linked-read whole-genome sequencing from 10X Genomics, we document seven major SV classes at ~5 kb SV resolution. Our results encompass 11,735 distinct large SV sites, 38.1% of which are novel and 16.8% of which are balanced or complex. We characterize 16 recurrent subclasses of complex SV (cxSV), revealing that: (1) cxSV are larger and rarer than canonical SV; (2) each genome harbors 14 large cxSV on average; (3) 84.4% of large cxSVs involve inversion; and (4) most large cxSV (93.8%) have not been delineated in previous studies. Rare SVs are more likely to disrupt coding and regulatory non-coding loci, particularly when truncating constrained and disease-associated genes. We also identify multiple cases of catastrophic chromosomal rearrangements known as chromoanagenesis, including somatic chromoanasynthesis, and extreme balanced germline chromothripsis events involving up to 65 breakpoints and 60.6 Mb across four chromosomes, further defining rare categories of extreme cxSV.

Conclusions: These data provide a foundational map of large SV in the morbid human genome and demonstrate a previously underappreciated abundance and diversity of cxSV that should be considered in genomic studies of human disease.
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http://dx.doi.org/10.1186/s13059-017-1158-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5338099PMC
March 2017

Molecular and clinical analysis of ALPL in a cohort of patients with suspicion of Hypophosphatasia.

Am J Med Genet A 2017 Mar 27;173(3):601-610. Epub 2017 Jan 27.

Institute of Medical and Molecular Genetics (INGEMM), Hospital Universitario La Paz, IdiPAZ, Universidad Autónoma de Madrid, Madrid, Spain.

Hypophosphatasia (HPP) is a rare autosomal dominant or recessive metabolic disorder caused by mutations in the tissue nonspecific alkaline phosphatase gene (ALPL). To date, over 300 different mutations in ALPL have been identified. Disease severity is widely variable with severe forms usually manifesting during perinatal and/or infantile periods while mild forms are sometimes only diagnosed in adulthood or remain undiagnosed. Common clinical features of HPP are defects in bone and tooth mineralization along with the biochemical hallmark of decreased serum alkaline phosphatase activity. The incidence of severe HPP is approximately 1 in 300,000 in Europe and 1 in 100,000 in Canada. We present the clinical and molecular findings of 83 probands and 28 family members, referred for genetic analysis due to a clinical and biochemical suspicion of HPP. Patient referrals included those with isolated low alkaline phosphatase levels and without any additional clinical features, to those with a severe skeletal dysplasia. Thirty-six (43.3%) probands were found to have pathogenic ALPL mutations. Eleven previously unreported mutations were identified, thus adding to the ever increasing list of ALPL mutations. Seven of these eleven were inherited in an autosomal dominant manner while the remaining four were observed in the homozygous state. Thus, this study includes a large number of well-characterized patients with hypophosphatasemia which has permitted us to study the genotype:phenotype correlation. Accurate diagnosis of patients with a clinical suspicion of HPP is crucial as not only is the disease life-threatening but the patients may be offered bone targeted enzymatic replacement therapy. © 2017 Wiley Periodicals, Inc.
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http://dx.doi.org/10.1002/ajmg.a.37991DOI Listing
March 2017

The genomic landscape of balanced cytogenetic abnormalities associated with human congenital anomalies.

Nat Genet 2017 01 14;49(1):36-45. Epub 2016 Nov 14.

Molecular Neurogenetics Unit, Center for Human Genetic Research, Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA.

Despite the clinical significance of balanced chromosomal abnormalities (BCAs), their characterization has largely been restricted to cytogenetic resolution. We explored the landscape of BCAs at nucleotide resolution in 273 subjects with a spectrum of congenital anomalies. Whole-genome sequencing revised 93% of karyotypes and demonstrated complexity that was cryptic to karyotyping in 21% of BCAs, highlighting the limitations of conventional cytogenetic approaches. At least 33.9% of BCAs resulted in gene disruption that likely contributed to the developmental phenotype, 5.2% were associated with pathogenic genomic imbalances, and 7.3% disrupted topologically associated domains (TADs) encompassing known syndromic loci. Remarkably, BCA breakpoints in eight subjects altered a single TAD encompassing MEF2C, a known driver of 5q14.3 microdeletion syndrome, resulting in decreased MEF2C expression. We propose that sequence-level resolution dramatically improves prediction of clinical outcomes for balanced rearrangements and provides insight into new pathogenic mechanisms, such as altered regulation due to changes in chromosome topology.
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http://dx.doi.org/10.1038/ng.3720DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5307971PMC
January 2017

In Silico Modeling of Liver Metabolism in a Human Disease Reveals a Key Enzyme for Histidine and Histamine Homeostasis.

Cell Rep 2016 06 26;15(10):2292-2300. Epub 2016 May 26.

Telethon Institute of Genetics and Medicine, 80078 Pozzuoli, Italy; Department of Chemical, Materials and Industrial Engineering, Federico II University, 80125 Naples, Italy. Electronic address:

Primary hyperoxaluria type I (PH1) is an autosomal-recessive inborn error of liver metabolism caused by alanine:glyoxylate aminotransferase (AGT) deficiency. In silico modeling of liver metabolism in PH1 recapitulated accumulation of known biomarkers as well as alteration of histidine and histamine levels, which we confirmed in vitro, in vivo, and in PH1 patients. AGT-deficient mice showed decreased vascular permeability, a readout of in vivo histamine activity. Histamine reduction is most likely caused by increased catabolism of the histamine precursor histidine, triggered by rerouting of alanine flux from AGT to the glutamic-pyruvate transaminase (GPT, also known as the alanine-transaminase ALT). Alanine administration reduces histamine levels in wild-type mice, while overexpression of GPT in PH1 mice increases plasma histidine, normalizes histamine levels, restores vascular permeability, and decreases urinary oxalate levels. Our work demonstrates that genome-scale metabolic models are clinically relevant and can link genotype to phenotype in metabolic disorders.
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http://dx.doi.org/10.1016/j.celrep.2016.05.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4906368PMC
June 2016

Updated genetic testing of Italian patients referred with a clinical diagnosis of primary hyperoxaluria.

J Nephrol 2017 Apr 5;30(2):219-225. Epub 2016 Mar 5.

Department of Clinical and Biological Sciences, University of Torino, San Luigi University Hospital, Regione Gonzole 10, 10040, Orbassano, TO, Italy.

Background: Primary hyperoxaluria (PH) is a rare autosomal recessive disease commonly arising in childhood and presenting with nephrolithiasis, nephrocalcinosis and/or chronic renal failure. Three genes are currently known as responsible: alanine-glyoxylate aminotransferase (AGXT, PH type 1), glyoxylate reductase/hydroxypyruvate reductase (GRHPR, PH type 2), and 4-hydroxy-2-oxoglutarate aldolase (HOGA1, PH type 3). In our Centre, at the end of 2014 molecular diagnosis of PH1 had been performed in 80 patients, while one patient received a PH2 diagnosis.

Materials And Methods: Fifteen patients referred to our Centre and suspected to have PH on clinical grounds were negative for pathogenic variants in the entire coding sequence and exon-intron boundaries of the AGXT gene. Therefore, we extended the analysis to the AGXT promoter region and the GRHPR and HOGA1 genes.

Results: Two patients were heterozygous for two novel AGXT-promoter variants (c.-647C > T, c.-424C > T) that were probably non pathogenic. One patient was homozygous for a novel HOGA1 variant of intron 2 (c.341-81delT), whose pathogenicity predicted by in silico splicing tools was not confirmed by a minigene splicing assay in COS-7 and HEK293T cells.

Conclusion: New genetic subtypes of PH can be hypothesized in our patients, that may be caused by mutations in other gene encoding proteins of glyoxylate metabolism. Alternatively, some kind of mutations (e.g., deletions/duplications, deep intronic splicing regulatory variants) could be missed in a few cases, similarly to other genetic diseases.
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http://dx.doi.org/10.1007/s40620-016-0287-4DOI Listing
April 2017

Clinical, neuroradiological and molecular characterization of cerebellar dysplasia with cysts (Poretti-Boltshauser syndrome).

Eur J Hum Genet 2016 08 2;24(9):1262-7. Epub 2016 Mar 2.

CSS-Mendel Institute, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy.

Cerebellar dysplasia with cysts and abnormal shape of the fourth ventricle, in the absence of significant supratentorial anomalies and of muscular involvement, defines recessively inherited Poretti-Boltshauser syndrome (PBS). Clinical features comprise non-progressive cerebellar ataxia, intellectual disability of variable degree, language impairment, ocular motor apraxia and frequent occurrence of myopia or retinopathy. Recently, loss-of-function variants in the LAMA1 gene were identified in six probands with PBS. Here we report the detailed clinical, neuroimaging and genetic characterization of 18 PBS patients from 15 unrelated families. Biallelic LAMA1 variants were identified in 14 families (93%). The only non-mutated proband presented atypical clinical and neuroimaging features, challenging the diagnosis of PBS. Sixteen distinct variants were identified, which were all novel. In particular, the frameshift variant c.[2935delA] recurred in six unrelated families on a shared haplotype, suggesting a founder effect. No LAMA1 variants could be detected in 27 probands with different cerebellar dysplasias or non-progressive cerebellar ataxia, confirming the strong correlate between LAMA1 variants and PBS.
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http://dx.doi.org/10.1038/ejhg.2016.19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4913877PMC
August 2016

A new case of 13q12.2q13.1 microdeletion syndrome contributes to phenotype delineation.

Case Rep Genet 2014 23;2014:470830. Epub 2014 Nov 23.

Department of Medical Sciences, University of Torino, Via Santena 19, 10126 Torino, Italy ; Medical Genetics, "Città della Salute e della Scienza" University Hospital, 10126 Torino, Italy.

A recently described genetic disorder has been associated with 13q12.3 microdeletion spanning three genes, namely, KATNAL1, LINC00426, and HMGB1. Here, we report a new case with similar clinical features that we have followed from birth to 5 years old. The child carried a complex rearrangement with a double translocation: 46,XX,t(7;13)(p15;q14),t(11;15)(q23;q22). Array-CGH identified a de novo microdeletion at 13q12.2q13.1 spanning 3-3.4 Mb and overlapping 13q12.3 critical region. Clinical features resembling those reported in the literature confirm the existence of a distinct 13q12.3 microdeletion syndrome and provide further evidence that is useful to characterize its phenotypic expression during the 5 years of development.
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http://dx.doi.org/10.1155/2014/470830DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4259072PMC
December 2014

Large cryptic genomic rearrangements with apparently normal karyotypes detected by array-CGH.

Mol Cytogenet 2014 19;7(1):82. Epub 2014 Nov 19.

Department of Medical Sciences, University of Torino, via Santena 19, 10126 Torino, Italy ; Città della Salute e della Scienza University Hospital, Medical Genetics Unit, Turin, Italy.

Background: Conventional karyotyping (550 bands resolution) is able to identify chromosomal aberrations >5-10 Mb, which represent a known cause of intellectual disability/developmental delay (ID/DD) and/or multiple congenital anomalies (MCA). Array-Comparative Genomic Hybridization (array-CGH) has increased the diagnostic yield of 15-20%.

Results: In a cohort of 700 ID/DD cases with or without MCA, including 15 prenatal diagnoses, we identified a subgroup of seven patients with a normal karyotype and a large complex rearrangement detected by array-CGH (at least 6, and up to 18 Mb). FISH analysis could be performed on six cases and showed that rearrangements were translocation derivatives, indistinguishable from a normal karyotype as they involved a similar band pattern and size. Five were inherited from a parent with a balanced translocation, whereas two were apparently de novo. Genes spanning the rearrangements could be associated with some phenotypic features in three cases (case 3: DOCK8; case 4: GATA3, AKR1C4; case 6: AS/PWS deletion, CHRNA7), and in two, likely disease genes were present (case 5: NR2F2, TP63, IGF1R; case 7: CDON). Three of our cases were prenatal diagnoses with an apparently normal karyotype.

Conclusions: Large complex rearrangements of up to 18 Mb, involving chromosomal regions with similar size and band appearance may be overlooked by conventional karyotyping. Array-CGH allows a precise chromosomal diagnosis and recurrence risk definition, further confirming this analysis as a first tier approach to clarify molecular bases of ID/DD and/or MCA. In prenatal tests, array-CGH is confirmed as an important tool to avoid false negative results due to karyotype intrinsic limit of detection.
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http://dx.doi.org/10.1186/s13039-014-0082-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4247713PMC
December 2014

SCN1B gene variants in Brugada Syndrome: a study of 145 SCN5A-negative patients.

Sci Rep 2014 Sep 25;4:6470. Epub 2014 Sep 25.

1] Medical Genetics, University of Torino, Dept. Clinical &Biological Sciences, Torino, Italy [2] Medical Genetics, San Luigi University Hospital, Orbassano, Italy.

Brugada syndrome is characterised by a typical ECG with ST segment elevation in the right precordial leads. Individuals with this condition are susceptible to ventricular arrhythmias and sudden cardiac death. The principal gene responsible for this syndrome is SCN5A, which encodes the α-subunit of the Nav1.5 voltage-gated sodium channel. Mutations involving other genes have been increasingly reported, but their contribution to Brugada syndrome has been poorly investigated. Here we focused on the SCN1B gene, which encodes the β1-subunit of the voltage-gated sodium channel and its soluble β1b isoform. SCN1B mutations have been associated with Brugada syndrome as well as with other cardiac arrhythmias and familial epilepsy. In this study, we have analysed SCN1B exons (including the alternatively-spliced exon 3A) and 3'UTR in 145 unrelated SCN5A-negative patients from a single centre. We took special care to report all identified variants (including polymorphisms), following the current nomenclature guidelines and considering both isoforms. We found two known and two novel (and likely deleterious) SCN1B variants. We also found two novel changes with low evidence of pathogenicity. Our findings contribute more evidence regarding the occurrence of SCN1B variants in Brugada syndrome, albeit with a low prevalence, which is in agreement with previous reports.
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http://dx.doi.org/10.1038/srep06470DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5377327PMC
September 2014

S81L and G170R mutations causing Primary Hyperoxaluria type I in homozygosis and heterozygosis: an example of positive interallelic complementation.

Hum Mol Genet 2014 Nov 2;23(22):5998-6007. Epub 2014 Jul 2.

Department of Life Sciences and Reproduction, University of Verona, Verona, Italy and.

Primary Hyperoxaluria type I (PH1) is a rare disease due to the deficit of peroxisomal alanine:glyoxylate aminotransferase (AGT), a homodimeric pyridoxal-5'-phosphate (PLP) enzyme present in humans as major (Ma) and minor (Mi) allele. PH1-causing mutations are mostly missense identified in both homozygous and compound heterozygous patients. Until now, the pathogenesis of PH1 has been only studied by approaches mimicking homozygous patients, whereas the molecular aspects of the genotype-enzymatic-clinical phenotype relationship in compound heterozygous patients are completely unknown. Here, for the first time, we elucidate the enzymatic phenotype linked to the S81L mutation on AGT-Ma, relative to a PLP-binding residue, and how it changes when the most common mutation G170R on AGT-Mi, known to cause AGT mistargeting without affecting the enzyme functionality, is present in the second allele. By using a bicistronic eukaryotic expression vector, we demonstrate that (i) S81L-Ma is mainly in its apo-form and has a significant peroxisomal localization and (ii) S81L and G170R monomers interact giving rise to the G170R-Mi/S81L-Ma holo-form, which is imported into peroxisomes and exhibits an enhanced functionality with respect to the parental enzymes. These data, integrated with the biochemical features of the heterodimer and the homodimeric counterparts in their purified recombinant form, (i) highlight the molecular basis of the pathogenicity of S81L-Ma and (ii) provide evidence for a positive interallelic complementation between the S81L and G170R monomers. Our study represents a valid approach to investigate the molecular pathogenesis of PH1 in compound heterozygous patients.
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http://dx.doi.org/10.1093/hmg/ddu329DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4204775PMC
November 2014

Data from a large European study indicate that the outcome of primary hyperoxaluria type 1 correlates with the AGXT mutation type.

Kidney Int 2014 Dec 2;86(6):1197-204. Epub 2014 Jul 2.

Clinical Biochemistry, UCL Hospitals, London, UK.

Primary hyperoxaluria type 1 displays a heterogeneous phenotype, likely to be affected by genetic and non-genetic factors, including timeliness of diagnosis and quality of care. As previous genotype-phenotype studies were hampered by limited patient numbers the European OxalEurope Consortium was constituted. This preliminary retrospective report is based on 526 patients of which 410 have the AGXT genotype defined. We grouped mutations by the predicted effect as null, missense leading to mistargeting (G170R), and other missense, and analyzed their phenotypic correlations. Median age of end-stage renal disease increased from 9.9 for 88 homozygous null patients, 11.5 for 42 heterozygous null/missense, 16.9 for 116 homozygous missense patients, 25.1 for 61 G170R/null patients, 31.2 for 32 G170R/missense patients, and 33.9 years for 71 homozygous G170R patients. The outcome of some recurrent missense mutations (p.I244T, p.F152I, p.M195R, p.D201E, p.S81L, p.R36C) and an unprecedented number of G170R homozygotes is described in detail. Diagnosis is still delayed and actions aimed at increasing awareness of primary hyperoxaluria type 1 are recommended. Thus, in addition to G170R, other causative mutations are associated with later onset of end-stage renal disease. The OxalEurope registry will provide necessary tools for characterizing those genetic and non-genetic factors through a combination of genetic, functional, and biostatistical approaches.
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http://dx.doi.org/10.1038/ki.2014.222DOI Listing
December 2014

A founder MLH1 mutation in Lynch syndrome families from Piedmont, Italy, is associated with an increased risk of pancreatic tumours and diverse immunohistochemical patterns.

Fam Cancer 2014 Sep;13(3):401-13

Department of Medical Sciences, University of Turin, Via Santena 19 Torino, 10126, Turin, Italy,

The MLH1 c.2252_2253delAA mutation was found in 11 unrelated families from a restricted area south-west of Turin among 140 families with mutations in the mismatch repair genes. The mutation is located in the highly conserved C-terminal region, responsible for dimerization with the PMS2 protein. Twenty-five tumour tissues from 61 individuals with the c.2252_2253delAA mutation were tested for microsatellite instability (MSI) and protein expression. We compared the clinical features of these families versus the rest of our cohort and screened for a founder effect. All but one tumours showed the MSI-high mutator phenotype. Normal, focal and lack of MLH1 staining were observed in 16, 36 and 48 % of tumours, respectively. PMS2 expression was always lost. The mutation co-segregated with Lynch syndrome-related cancers in all informative families. All families but one fulfilled Amsterdam criteria, a frequency higher than in other MLH1 mutants. This was even more evident for AC II (72.7 vs. 57.5 %). Moreover, all families had at least one colon cancer diagnosed before 50 years and one case with multiple Lynch syndrome-related tumours. Interestingly, a statistically significant (p = 0.0057) higher frequency of pancreatic tumours was observed compared to families with other MLH1 mutations: 8.2 % of affected individuals versus 1.6 %. Haplotype analysis demonstrated a common ancestral origin of the mutation, which originated about 1,550 years ago. The mutation is currently classified as having an uncertain clinical significance. Clinical features, tissue analysis and co-segregation with disease strongly support the hypothesis that the MLH1 c.2252_2253delAA mutation has a pathogenic effect.
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http://dx.doi.org/10.1007/s10689-014-9726-3DOI Listing
September 2014

Cerebrotendinous xanthomatosis: recurrence of the CYP27A1 mutation p.Arg479Cys in Sardinia.

Neurol Sci 2014 Aug 2;35(8):1303-5. Epub 2014 Mar 2.

Medical Genetics Unit, San Luigi Gonzaga University Hospital, Regione Gonzole 10, 10043, Orbassano, TO, Italy,

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http://dx.doi.org/10.1007/s10072-014-1696-6DOI Listing
August 2014

3q26.33-3q27.2 microdeletion: a new microdeletion syndrome?

Eur J Med Genet 2013 Apr 26;56(4):216-21. Epub 2013 Jan 26.

Division of Medical Genetics, Galliera Hospital, Via Volta 6, 16128 Genova, Italy.

We describe three unrelated patients of European descent carrying an overlapping 3q26.33-3q27.2 microdeletion who share common clinical features: neonatal hypotonia, severe feeding problems, specific facial features, abnormal dentition, recurrent upper airways infections, developmental delay and severe growth impairment. One of the patients carries a smaller deletion and presents a milder phenotype. We propose that 3q26.33-3q27.2 microdeletion may represent a novel condition caused by the haploinsufficiency of dosage sensitive genes, several of which are involved in brain development.
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http://dx.doi.org/10.1016/j.ejmg.2013.01.005DOI Listing
April 2013

BClI polymorphism of the glucocorticoid receptor gene is associated with increased obesity, impaired glucose metabolism and dyslipidaemia in patients with Addison's disease.

Clin Endocrinol (Oxf) 2012 Dec;77(6):863-70

Department of Clinical and Biological Sciences, University of Turin, Turin, Italy.

Object: Although glucocorticoids are essential for health, several studies have shown that glucocorticoids replacement in Addison's disease might be involved in anthropometric and metabolic impairment, with increased cardiovascular risk, namely if conventional doses are used. As the effects of glucocorticoids are mediated by the glucocorticoid receptor, encoded by NR3C1 gene, different polymorphisms in the NR3C1 gene have been linked to altered glucocorticoid sensitivity in general population as well as in patients with obesity or metabolic syndrome.

Design: We investigated the impact of glucocorticoid receptor gene polymorphisms, including the BclI, N363S and ER22/23EK variants, on anthropometric parameters (BMI and waist circumference), metabolic profile (HOMA, OGTT and serum lipids) and ACTH levels in 50 patients with Addison's disease (34 women and 16 men, age 20-82 year) under glucocorticoids replacement.

Results: Neither N363S nor ER22/23EK variants were significantly associated with anthropometric, metabolic or hormonal parameters, while patients carrying the homozygous BclI polymorphism GG (n = 4) showed higher (P < 0·05) BMI, waist circumference, HOMA and 2-h glucose levels after OGTT, as well as total cholesterol and triglycerides than those with wild-type genotype CC (n = 28) or heterozygous CG (n = 18). The totality of GG patients was connoted by abdominal adiposity, impaired glucose tolerance/diabetes mellitus or dyslipidaemia, while a lower percentage of CC or CG patients showed some anthropometric and metabolic alterations.

Conclusion: These results suggest that BclI polymorphism may influence the sensitivity to glucocorticoids in patients with Addison's disease and may contribute, along with other factors, to the increase in central adiposity, impaired glucose metabolism and dyslipidaemia.
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http://dx.doi.org/10.1111/j.1365-2265.2012.04439.xDOI Listing
December 2012

Primary hyperoxaluria Type 1: indications for screening and guidance for diagnosis and treatment.

Nephrol Dial Transplant 2012 May;27(5):1729-36

Reference Center for Rare Renal Diseases & EPICIME, Department of Paediatrics, Hospices Civils de Lyon and Université Claude-Bernard Lyon 1, Lyon, France.

Primary hyperoxaluria Type 1 is a rare autosomal recessive inborn error of glyoxylate metabolism, caused by a deficiency of the liver-specific enzyme alanine:glyoxylate aminotransferase. The disorder results in overproduction and excessive urinary excretion of oxalate, causing recurrent urolithiasis and nephrocalcinosis. As glomerular filtration rate declines due to progressive renal involvement, oxalate accumulates leading to systemic oxalosis. The diagnosis is based on clinical and sonographic findings, urine oxalate assessment, enzymology and/or DNA analysis. Early initiation of conservative treatment (high fluid intake, pyridoxine, inhibitors of calcium oxalate crystallization) aims at maintaining renal function. In chronic kidney disease Stages 4 and 5, the best outcomes to date were achieved with combined liver-kidney transplantation.
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http://dx.doi.org/10.1093/ndt/gfs078DOI Listing
May 2012

NOTCH3 gene mutations in subjects clinically suspected of CADASIL.

J Neurol Sci 2011 Aug 26;307(1-2):144-8. Epub 2011 May 26.

Department of Laboratory Medicine, Medical Genetics, Niguarda Ca' Granda Hospital, Milan, Italy.

Background: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited cerebrovascular disease due to mutations involving loss or gain of a cysteine residue in the NOTCH3 gene. A cluster of mutations around exons 3 and 4 was originally reported. Identification of pathogenic mutation is important for diagnostic confirmation of the disease, however genetic counselling and testing of relatives at risk is critical in mutation carriers.

Methods: Mutation analysis of the NOTCH3 gene was performed through direct sequencing in 140 patients with clinical suspicion of CADASIL. Patients underwent genetic counselling pre and post testing. The 2-23 exons containing all EGF-like domains were screened.

Results: 14 familial forms of the disease have been identified with 14 different causative mutations in exons 2, 3, 4, 5, 7, 10, 14, 19, 20 and 22 of the NOTCH3 gene; no pathogenetic mutations have been identified in exons 6 and 8; several genetic variations both in coding as well as in intronic regions were identified too.

Conclusions: Our data confirm the importance of screening the whole EGF-like domains region of NOTCH3 gene for the molecular diagnosis of CADASIL among the Italian population too. Moreover genetic variants different from loss or gain of a cysteine residue are identified and presented.
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http://dx.doi.org/10.1016/j.jns.2011.04.019DOI Listing
August 2011

Novel human pathological mutations. Gene symbol: AGXT. Disease: hyperoxaluria.

Hum Genet 2010 Apr;127(4):468

S. Luigi Gonzaga Hospital, Medical Genetics Unit, University of Torino, Orbassano (TO), Italy.

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April 2010

Modeling the effect of 3 missense AGXT mutations on dimerization of the AGT enzyme in primary hyperoxaluria type 1.

J Nephrol 2010 Nov-Dec;23(6):667-76

Department of Clinical and Biological Sciences, University of Turin, Regione Gonzole, Orbassano, Italy.

Introduction: Mutations of the AGXT gene encoding the alanine:glyoxylate aminotransferase liver enzyme (AGT) cause primary hyperoxaluria type 1 (PH1). Here we report a molecular modeling study of selected missense AGXT mutations: the common Gly170Arg and the recently described Gly47Arg and Ser81Leu variants, predicted to be pathogenic using standard criteria.

Methods: Taking advantage of the refined 3D structure of AGT, we computed the dimerization energy of the wild-type and mutated proteins.

Results: Molecular modeling predicted that Gly47Arg affects dimerization with a similar effect to that shown previously for Gly170Arg through classical biochemical approaches. In contrast, no effect on dimerization was predicted for Ser81Leu. Therefore, this probably demonstrates pathogenic properties via a different mechanism, similar to that described for the adjacent Gly82Glu mutation that affects pyridoxine binding.

Conclusion: This study shows that the molecular modeling approach can contribute to evaluating the pathogenicity of some missense variants that affect dimerization. However, in silico studies--aimed to assess the relationship between structural change and biological effects--require the integrated use of more than 1 tool.
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January 2011

Prospective assessment of XPD Lys751Gln and XRCC1 Arg399Gln single nucleotide polymorphisms in lung cancer.

Clin Cancer Res 2007 May;13(10):2876-81

Department of Clinical and Biological Sciences, University of Torino, Turin, Italy.

Purpose: XRCC1 and XPD play key roles in the repair of DNA lesions and adducts. Contrasting findings have been reported on the effect of polymorphisms of these genes on the response to platinum-based chemotherapy in advanced non-small-cell lung cancer (NSCLC). This study aimed to investigate the relationship between the XPD Lys751Gln and XRCC1 Arg399Gln genotypes and outcome in lung cancer patients.

Experimental Design: We genotyped 203 NSCLC and 45 small-cell lung carcinoma (SCLC) patients for the two polymorphisms. Most of the patients (81%) received a platinum-based chemotherapy.

Results: The patients' genotype frequencies did not significantly differ from controls and both groups were in Hardy-Weinberg equilibrium for the two polymorphisms. The XRCC1399 Gln/Gln variant genotype was associated with a higher median survival time (80 weeks versus 54.6 weeks for the Arg/Gln heterozygous and 55.6 weeks for the wild-type Arg/Arg genotype; P=0.09). At the multivariable analysis adjusted for histology, stage of the disease, performance status, age, and gender, the Gln/Gln genotype was associated with a better survival of borderline significance in the subgroup of patients treated with cisplatin (hazard ratio, 0.55; 95% CI, 0.30-1.00); this association became significant for those with grade 3-4 clinical toxicity (hazard ratio, 0.46; 95% CI, 0.22-0.98). No association between XPD Lys751Gln genotype and clinical outcome was found.

Conclusion: This prospective investigation provides suggestive evidence of a favorable effect of the XRCC1399 Gln/Gln genotype on survival in platinum-treated NSCLC and, for the first time, in SCLC patients also. This contrasts with other authors who did not include non-platinum-treated patients, but it does fit the expectation for a suboptimal ability to remove DNA adducts.
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http://dx.doi.org/10.1158/1078-0432.CCR-06-2543DOI Listing
May 2007