Identification of an NF1 Microdeletion with Optical Genome Mapping.

Neurofibromatosis type 1 (NF1) is a clinically heterogeneous neurocutaneous disorder inherited in autosomal dominant manner. Approximately 5-10% of the cases are caused by NF1 microdeletions involving the NF1 gene and its flanking regions. Microdeletions, which lead to more severe clinical manifestations, can be subclassified into four different types (type 1, 2, 3 and atypical) according to their size, the genomic location of the breakpoints and the number of genes included within the deletion. Besides the prominent hallmarks of NF1, patients with NF1 microdeletions frequently exhibit specific additional clinical manifestations like dysmorphic facial features, macrocephaly, overgrowth, global developmental delay, cognitive disability and an increased risk of malignancies. It is important to identify the genes co-deleted with NF1, because they are likely to have an effect on the clinical manifestation. Multiplex ligation-dependent probe amplification (MLPA) and microarray analysis are the primary techniques for the investigation of NF1 microdeletions. However, based on previous research, optical genome mapping (OGM) could also serve as an alternative method to identify copy number variations (CNVs). Here, we present a case with NF1 microdeletion identified by means of OGM and demonstrate that this novel technology is a suitable tool for the identification and classification of the NF1 microdeletions.

Diagnostic difficulties and possibilities of NF1-like syndromes in childhood.

BACKGROUND: Neurofibromatosis type 1 (NF1), which is caused by heterozygous inactivating pathogenic variants in the NF1, has poor phenotypic expressivity in the early years of life and there are numerous conditions, including many other tumor predisposition syndromes, that can mimic its appearance. These are collectively termed NF1-like syndromes and are also connected by their genetic background. Therefore, the NF1's clinical diagnostic efficiency in childhood could be difficult and commonly should be completed with genetic testing. METHODS: To estimate the number of syndromes/conditions that could mimic NF1, we compiled them through an extensive search of the scientific literature. To test the utility of NF1's National Institutes of Health (NIH) clinical diagnostic criteria, which have been in use for a long time, we analyzed the data of a 40-member pediatric cohort with symptoms of the NF1-like syndromes' overlapping phenotype and performed NF1 genetic test, and established the average age when diagnostic suspicion arises. To facilitate timely identification, we compiled strongly suggestive phenotypic features and anamnestic data. RESULTS: In our cohort the utility of NF1's clinical diagnostic criteria were very limited (sensitivity: 80%, specificity: 30%). Only 53% of children with clinically diagnosed NF1 had a detectable NF1 pathogenic variation, whereas 40% of patients without fulfilled clinical criteria tested positive. The average age at first genetic counseling was 9 years, and 40% of children were referred after at least one tumor had already been diagnosed. These results highlight the need to improve NF1-like syndromes' diagnostic efficiency in childhood. We collected the most extensive spectrum of NF1-like syndromes to help the physicians in differential diagnosis. We recommend the detailed, non-invasive clinical evaluation of patients before referring them to a clinical geneticist. CONCLUSIONS: Early diagnosis of NF1-like syndromes can help to prevent severe complications by appropriate monitoring and management. We propose a potential screening, diagnostic and management strategy based on our findings and recent scientific knowledge.

What should we consider in the case of combined Down- and 47,XY,+i(X)(q10) Klinefelter syndromes? The unique case of a male newborn and review of the literature.

BACKGROUND: Double aneuploidies - especially in combination with structural aberrations - are extremely rare among liveborns. The most frequent association is that of Down (DS) and Klinefelter syndromes (KS). We present the case of a male newborn with a unique 47,XY,+ 21[80%]/48,XY,+i(X)(q10),+ 21[20%] karyotype, hypothesize about his future phenotype, discuss the aspects of management and review the literature. CASE PRESENTATION: The additional association of isochromosome Xq (i(X)(q10)) could be the result of a threefold non-disjunction event. 47,XY,+i(X)(q10) KS is not common and its symptoms differ from the classical KS phenotype. In combined DS and i(X)(q10) KS, the anticipatory phenotype is not simply the sum of the individual syndromic characteristics. This genotype is associated with higher risk for several diseases and certain conditions with more pronounced appearance: emotional and behavioral disorders; poorer mental and physical quality of life; lower muscle mass/tone/strength; connective tissue weakness; muscle hypotonia and feeding difficulties; osteopenia/-porosis with earlier beginning and faster progression; different types of congenital heart diseases; more common occurrence of hypertension; increased susceptibility to infections and female predominant autoimmune diseases; higher risk for hematological malignancies and testicular tumors. CONCLUSIONS: In multiple aneuploidies, the alterations have the potential to weaken or enhance each other, or they may not have modifying effects at all. Prenatal ultrasound signs are not obligatory symptoms of numerous chromosomal anomalies (specifically those involving supernumerary sex chromosomes), therefore combined prenatal screening has pertinence in uncomplicated pregnancies as well.

Pharmacokinetics, pharmacodynamics, and safety of moss-aGalactosidase A in patients with Fabry disease.

Moss-aGalactosidase A (moss-aGal) is a moss-derived version of human α-galactosidase developed for enzyme replacement therapy in patients with Fabry disease. It exhibits a homogenous N-glycosylation profile with >90% mannose-terminated glycans. In contrast to mammalian cell produced α-galactosidase, moss-aGal does not rely on mannose-6-phosphate receptor mediated endocytosis but targets the mannose receptor for tissue uptake. We conducted a phase 1 clinical trial with moss-aGal in six patients with confirmed diagnosis of Fabry disease during a 28-day schedule. All patients received a single dose of 0.2 mg/kg moss-aGal by i.v.-infusion. Primary endpoints of the trial were safety and pharmacokinetics; secondary endpoints were pharmacodynamics by analyzing urine and plasma Gb3 and lyso-Gb3 concentrations. In all patients, the administered single dose was well tolerated. No safety issues were observed. Pharmacokinetic data revealed a stable nonlinear profile with a short plasma half-life of moss-aGal of 14 minutes. After one single dose of moss-aGal, urinary Gb3 concentrations decreased up to 23% 7 days and up to 60% 28 days post-dose. Plasma concentrations of lyso-Gb3 decreased by 3.8% and of Gb3 by 11% 28 days post-dose. These data reveal that a single dose of moss-aGal was safe, well tolerated, and led to a prolonged reduction of Gb3 excretion. As previously shown, moss-aGal is taken up via the mannose receptor, which is expressed on macrophages but also on endothelial and kidney cells. Thus, these data indicate that moss-aGal may target kidney cells. After these promising results, phase 2/3 clinical trials are in preparation.

Study of patterns of inheritance of premature ovarian failure syndrome carrying maternal and paternal premutations.

BACKGROUND: Premature ovarian failure / primary ovarian insufficiency (POF/POI) associated with the mutations of the FMR1 (Fragile-X Mental Retardation 1) gene belongs to the group of the so-called trinucleotide expansion diseases. Our aim was to analyse the relationship between the paternally inherited premutation (PIP) and the maternally inherited premutation (MIP) by the examination of the family members of women with POF, carrying the premutation allele confirmed by molecular genetic testing. METHODS: Molecular genetic testing was performed in the patients of the 1st Department of Obstetrics and Gynecology with suspected premature ovarian failure. First we performed the southern blot analyses and for the certified premutation cases we used the Repeat Primed PCR. RESULTS: Due to POF/POI, a total of 125 patients underwent genetic testing. The FMR1 gene trinucleotide repeat number was examined in the DNA samples of the patients, and in 15 cases (12%) deviations (CGG repeat number corresponding to premutation or gray zone) were detected. In 6 cases out of the 15 cases the CGG repeat number fell within the range of the so-called gray zone (41-54 CGG repeat) (4.8%, 6/125), and the FMR1 premutation (55-200 CGG repeat) ratio was 7.2% (9/125). In 4 out of the 15 cases we found differences in both alleles, one was a premutation allele, and the other allele showed a repeat number belonging to the gray zone. Out of 15 cases, only maternal inheritance (MIP) was detected in 2 cases, in one case the premutation allele (91 CGG repeat number), while in the other case an allele belonging to the gray zone (41 CGG repeat number) were inherited from their mothers. In 10 out of 15 cases, the patient inherited the premutation allele only from the father (PIP). In 5 out of the 10 cases (50%) the premutation allele was inherited from the father, and the repeat number ranged from 55 to 133. Out of 125 cases, 9 patients had detectable cytogenetic abnormalities (7.2%). CONCLUSIONS: The RP-PCR method can be used to define the smaller premutations and the exact CGG number. Due to the quantitative nature of the RP-PCR, it is possible to detect the mosaicism as well.

[Examination of sex chromosome abnormalities in childhood]. / Nemi kromoszóma-rendellenességek vizsgálata gyermekkorban.

INTRODUCTION: Early diagnosis of sex chromosome abnormalities is important because of prevention, family planning and optimal therapy. AIM: Investigation of the relationship between phenotype, age at time of diagnosis and therapeutic options in sex chromosome aberrations. METHOD: Processing data of 51 children with sex chromosome abnormalities who were diagnosed between 2009 and 2014 and examined at the 2nd. Department of Pediatrics, Semmelweis University, by the methods of anamnesis, family tree analysis, physical examination, karyotype analysis and fluorescent in situ hybridisation. RESULTS: 41% of the patients were diagnosed with Turner-, 18% with Klinefelter-, 10% with double-Y-, 6% with triple- and poly-X-syndrome, 19% with other gonadal dysgenesis and 6% with other abnormality. The average age at diagnosis: Turner- and Klinefelter-syndrome 10 years, other gonadal dysgenesis 9 years, 46,XX,t(X;10) 17 years, other abnormalities 1-2 years. CONCLUSIONS: Numerical aberrations of the sex chromosomes are more common than structural aberrations. Klinefelter-, triple- and poly-X-syndromes are underdiagnosed in childhood. Early diagnosis of Turner-syndrome and other gonadal dysgenesis is necessary to optimise therapy and prevent associated diseases. This can be achieved by modern prenatal diagnostic methods and targeted activity of family pediatricians. Orv Hetil. 2018; 159(27): 1121-1128.

[Trisomy 9p and clinical heterogeneity: case report of an unusual presentation]. / 9p triszómia és a klinikai sokszínuség: egy váratlan megjelenésu eset ismertetése.

Whole or partial trisomy of the short arm of chromosome 9 (9p) is considered to be one of the more frequent chromosome abnormalities compatible with life. The duplication may affect various organs, however the most common symptoms are certain specific facial dysmorphisms and abnormalities of the fingers, toes and nails. A one month old boy presented with failure to thrive, jaundice, ventricular septal defect (VSD) and dysmorphic face. He displayed symptoms of heart failure. The cardiologic examination revealed a significant VSD, hypoplasia of the aortic arch, pulmonary hypertension, decompensated circulatory failure and moderate left ventricle dysfunction. Routine cytogenetic analysis revealed a supernumerary marker chromosome. Fluorescence in situ hybridization (FISH) identified this as the short arm of chromosome 9. The child's karyotype was determined as 47,XY,+der(9)dup(9)(p10p24)dn. Due to his worsening condition and the high risk of the operation, it was decided to forego the procedure. After a short palliative care the child passed away. The child's clinical presentation and the uncharacteristic severity of his condition show that chromosome abnormalities involving duplicated genetic material are extremely heterogeneous. Thus treatment of each child should be individualized and may also involve difficult ethical considerations. Orv Hetil. 2018; 159(47): 1994-2000.

[Rapid first-tier genetic diagnosis in patients with Prader-Willi syndrome]. / Elsodleges genetikai vizsgálat Prader­Willi-szindróma igazolására.

INTRODUCTION: According to the international literature, DNA methylation analysis of the promoter region of SNRPN locus is the most efficient way to start genetic investigation in patients with suspected Prader-Willi syndrome. AIM: Our aim was to develop a simple, reliable first-tier diagnosis to confirm Prader-Willi syndrome, therefore to compare our self-designed simple, cost-efficient high-resolution melting analysis and the most commonly used methylation-specific multiplex ligation-dependent probe amplification to confirm Prader-Willi syndrome. METHOD: We studied 17 clinically suspected Prader-Willi syndrome children and their DNA samples. With self-designed primers, bisulfite-sensitive polymerase chain reaction, high-resolution melting analysis and, as a control, methylation-specific multiplex ligation-dependent probe amplification were performed. RESULTS: Prader-Willi syndrome was genetically confirmed in 6 out of 17 clinically suspected Prader-Willi syndrome patients. The results of high-resolution melting analysis and methylation-specific multiplex ligation-dependent probe amplification were equivalent in each case. CONCLUSION: Using our self-designed primers and altered bisulfite-specific PCR conditions, high-resolution melting analysis appears to be a simple, fast, reliable and effective method for primarily proving or excluding clinically suspected Prade-Willi syndrome cases. Orv Hetil. 2018; 159(2): 64-69.

[Steroid 21-hydroxylase deficiency, the most frequent cause of congenital adrenal hyperplasia]. / Szteroid-21-hidroxiláz-deficientia, a congenitalis adrenalis hyperplasia leggyakoribb oka.

Congenital adrenal hyperplasia is a group of genetic diseases due to the disablement of 7 genes; one of them is steroid 21-hydroxylase deficiency. The genes of congenital adrenal hyperplasia encode enzymes taking part in the steroidogenesis of adrenal gland. Steroid 21-hydroxylase deficiency is an autosomal recessive disorder caused by mutations of the steroid 21-hydroxylase gene. The mutations of steroid 21-hydroxylase gene cause 95% of the congenital adrenal hyperplasia cases. Although the non-classic steroid 21-hydroxylase deficiency with mild symptoms is seldom diagnosed, the classic steroid 21-hydroxylase deficiency may lead to life-threatening salt-wasting and adrenal crises due to the insufficient aldosterone and cortisol serum levels. The classic type requires life-long steroid replacement which may result in cushingoid side effects, and typical comorbidities may be also developed. The patients' quality of life is decreased, and their mortality is much higher than that of the population without steroid 21-hydroxylase deficiency. The diagnosis, consequences and the patients' life-long clinical care require a multidisciplinary approach: the specialists in pediatrics, internal medicine, endocrinology, laboratory medicine, genetic diagnostics, surgery, obstetrics-gynecology and psychology need to work together. Orv Hetil. 2018; 159(7): 269-277.

Targeted Next Generation Sequencing Approach in Patients Referred for Silver-Russell Syndrome Testing Increases the Mutation Detection Rate and Provides Decisive Information for Clinical Management.

OBJECTIVE: To investigate the contribution of differential diagnoses to the mutation spectrum of patients referred for Silver-Russell syndrome (SRS) testing. STUDY DESIGN: Forty-seven patients referred for molecular testing for SRS were examined after exclusion of one of the SRS-associated alterations. After clinical classification, a targeted next generation sequencing approach comprising 25 genes associated with other diagnoses or postulated as SRS candidate genes was performed. RESULTS: By applying the Netchine-Harbinson clinical scoring system, indication for molecular testing for SRS was confirmed in 15 out of 47 patients. In 4 out of these 15 patients, disease-causing variants were found in genes associated with other diagnoses. These patients carried mutations associated with Bloom syndrome, Mulibrey nanism, KBG syndrome, or IGF1R-associated short stature. We could not detect any pathogenic mutation in patients with a negative clinical score. CONCLUSIONS: Some of the differential diagnoses detected in the cohort presented here have a major impact on clinical management. Therefore, we emphasize that the molecular defects associated with these clinical pictures should be excluded before the clinical diagnosis "SRS" is made. Finally, we could show that a broad molecular approach including the differential diagnoses of SRS increases the detection rate.

[Williams-Beuren syndrome (Williams syndrome). Case report]. / Williams­Beuren-szindróma (Williams-szindróma).

Williams syndrome is a rare genetic disorder, that occurs equally in all ethnic groups and both sexes. The diagnosis might be missed during childhood in mild cases. However, establishing the diagnosis is important, not only to find the cause of intellectual disability but to look for cardiovascular, endocrine, psychiatry, urology and other conditions, which can occur at any age in the patients' lifetime. This case report presents the story of 47-year-old woman, who was admitted with haematemesis. During her stay on the ward, in the light of the distinctive facial features, mental retardation, and social behaviour patterns, the possibility of Williams syndrome emerged. Later, the diagnosis was confirmed by genetic analysis. This female is the oldest living patient with Williams syndrome in Hungary. Orv Hetil. 2017; 158(47): 1883-1888.

Examinations of maternal uniparental disomy and epimutations for chromosomes 6, 14, 16 and 20 in Silver-Russell syndrome-like phenotypes.

BACKGROUND: Silver-Russell syndrome (SRS) is a growth retardation disorder with a very broad molecular and clinical spectrum. Whereas the association of SRS with imprinting disturbances of chromosomes 11p15.5 and 7 is generally accepted, there are controversial discussions on the involvement of other molecular changes. The recent reports on the occurrence of maternal uniparental disomies of chromosomes 6, 16 and 20 (upd(6, 16, 20)mat), as well as 14q32 imprint alterations in patients with SRS phenotypes raise the question on the involvement of these mutations in the etiology of SRS. METHODS: A cohort of 54 growth retarded patients with SRS features was screened for aberrant methylation patterns of chromsomes 6, 14, 16 and 20. RESULTS: One carrier of a 14q32 epimutation was identified whereas epimutations and maternal UPD for chromosomes 6, 16 and 20 were excluded. CONCLUSIONS: Our data and those from the literature confirm that 14q32 disturbances significantly contribute to the mutation spectrum in this cohort. Furthermore, maternal uniparental disomy of chromosomes 6, 16 and 20 can be observed, but are rare. In case they occur they can be regarded as causative for clinical features.

[Flow cytometry in the diagnosis of hemophagocytic lymphohistiocytosis in a case with fatal outcome]. / Az áramlási citometria jelentosége a haemophagocytás lymphohistiocytosis diagnosztikájában egy fatális kimenetelu eset bemutatása kapcsán.

Hemophagocytic lymphohistiocytosis is a multisystem inflammation, generated by the uncontrolled and excessive activation of cytotoxic T lymphocytes and natural killer cells. Severe immunodeficiency and generalized macrophage activation can often be detected in the background of this life threatening disorder. It is classified as a primary immunodeficiency. Functional abnormalities of the perforin protein or defects in granule secretory mechanisms are caused by gene mutations in most cases. Diagnostic criteria of hemophagocytic lymphohistiocytosis are the following: fever, splenomegaly, cytopenias affecting at least two of the 3 lineages in peripheral blood, hypertriglyceridemia and hyperferritinemia, elevated serum level of soluble interleukin-2 receptor (sCD25), hypofibrinogenemia, hemophagocytosis in bone marrow and decreased cytotoxic T cell and natural killer cell activity. In this case report the authors summarize the utility of functional flow cytometry in the diagnosis of hemophagocytic lymphohistiocytosis. Using flow cytometry, elevated intracellular perforin content, decreased killing activity of cytotoxic T cells and natural killer cells, and impaired cell surface expression of CD107a (LAMP1 protein) from in vitro stimulated blood lymphocytes were detected. Abnormal secretion of perforin was also demonstrated. Genetic testing revealed mutation of the MUNC 13-4 gene, which confirmed the base of the abnormal flow cytometric findings. This case report demonstrates the value of functional flow cytometry in the rapid diagnosis of genetically determined hemophagocytic lymphohistiocytosis, a condition in which early diagnosis is critical for optimal management. The authors emphasize the significance of functional flow cytometry in the differential diagnosis of immunodeficiencies.

Comparative Analysis of Laboratory-Based and Spectroscopic Methods Used to Estimate the Algal Density of Chlorella vulgaris.

Chlorella vulgaris is of great importance in numerous exploratory or industrial applications (e.g., medicals, food, and feed additives). Rapid quantification of algal biomass is crucial in photobioreactors for the optimization of nutrient management and the estimation of production. The main goal of this study is to provide a simple, rapid, and not-resource-intensive estimation method for determining the algal density of C. vulgaris according to the measured parameters using UV-Vis spectrophotometry. Comparative assessment measurements were conducted with seven different methods (e.g., filtration, evaporation, chlorophyll a extraction, and detection of optical density and fluorescence) to determine algal biomass. By analyzing the entire spectra of diluted algae samples, optimal wavelengths were determined through a stepwise series of linear regression analyses by a novel correlation scanning method, facilitating accurate parameter estimation. Nonlinear formulas for spectrometry-based estimation processes were derived for each parameter. As a result, a general formula for biomass concentration estimation was developed, with recommendations for suitable measuring devices based on algae concentration levels. New values for magnesium content and the average single-cell weight of C. vulgaris were established, in addition to the development of a rapid, semiautomated cell counting method, improving efficiency and accuracy in algae quantification for cultivation and biotechnology applications.

Flow Cytometry-Based Assay to Detect Alpha Galactosidase Enzymatic Activity at the Cellular Level.

BACKGROUND: Fabry disease is a progressive, X chromosome-linked lysosomal storage disorder with multiple organ dysfunction. Due to the absence or reduced activity of alpha-galactosidase A (AGAL), glycosphingolipids, primarily globotriaosyl-ceramide (Gb3), concentrate in cells. In heterozygous women, symptomatology is heterogenous and currently routinely used fluorometry-based assays measuring mean activity mostly fail to uncover AGAL dysfunction. The aim was the development of a flow cytometry assay to measure AGAL activity in individual cells. METHODS: Conventional and multispectral imaging flow cytometry was used to detect AGAL activity. Specificity was validated using the GLA knockout (KO) Jurkat cell line and AGAL inhibitor 1-deoxygalactonojirimycin. The GLA KO cell line was generated via CRISPR-Cas9-based transfection, validated with exome sequencing, gene expression and substrate accumulation. RESULTS: Flow cytometric detection of specific AGAL activity is feasible with fluorescently labelled Gb3. In the case of Jurkat cells, a substrate concentration of 2.83 nmol/mL and 6 h of incubation are required. Quenching of the aspecific exofacial binding of Gb3 with 20% trypan blue solution is necessary for the specific detection of lysosomal substrate accumulation. CONCLUSION: A flow cytometry-based assay was developed for the quantitative detection of AGAL activity at the single-cell level, which may contribute to the diagnosis of Fabry patients.

A Cross-Sectional Study of the Dermatological Manifestations of Patients with Fabry Disease and the Assessment of Angiokeratomas with Multimodal Imaging.

Fabry disease (FD) is a multisystemic X-linked lysosomal storage disease that presents with angiokeratomas (AKs). Our objective was to investigate the clinical and morphologic features of AKs and to present two experimental techniques, multispectral imaging (MSI) and non-linear microscopy (NLM). A thorough dermatological examination was carried out in our 26 FD patients and dermoscopic images (n = 136) were evaluated for specific structures. MSI was used for the evaluation of AKs in seven patients. NLM was carried out to obtain histology samples of two AKs and two hemangiomas. Although AKs were the most common manifestation, the majority of patients presented an atypical distribution and appearance, which could cause a diagnostic challenge. Dermoscopy revealed lacunae (65%) and dotted vessels (56%) as the most common structures, with a whitish veil present in only 25%. Autofluorescence (405 nm) and diffuse reflectance (526 nm) images showed the underlying vasculature more prominently compared to dermoscopy. Using NLM, AKs and hemangiomas could be distinguished based on morphologic features. The clinical heterogeneity of FD can result in a diagnostic delay. Although AKs are often the first sign of FD, their presentation is diverse. A thorough dermatological examination and the evaluation of other cutaneous signs are essential for the early diagnosis of FD.

Molecular characterisation of 36 multilocus imprinting disturbance (MLID) patients: a comprehensive approach.

BACKGROUND: Imprinting disorders (ImpDis) comprise diseases which are caused by aberrant regulation of monoallelically and parent-of-origin-dependent expressed genes. A characteristic molecular change in ImpDis patients is aberrant methylation signatures at disease-specific loci, without an obvious DNA change at the specific differentially methylated region (DMR). However, there is a growing number of reports on multilocus imprinting disturbances (MLIDs), i.e. aberrant methylation at different DMRs in the same patient. These MLIDs account for a significant number of patients with specific ImpDis, and several reports indicate a central role of pathogenic maternal effect variants in their aetiology by affecting the maturation of the oocyte and the early embryo. Though several studies on the prevalence and the molecular causes of MLID have been conducted, homogeneous datasets comprising both genomic and methylation data are still lacking. RESULTS: Based on a cohort of 36 MLID patients, we here present both methylation data obtained from next-generation sequencing (NGS, ImprintSeq) approaches and whole-exome sequencing (WES). The compilation of methylation data did not reveal a disease-specific MLID episignature, and a predisposition for the phenotypic modification was not obvious as well. In fact, this lack of epigenotype-phenotype correlation might be related to the mosaic distribution of imprinting defects and their functional relevance in specific tissues. CONCLUSIONS: Due to the higher sensitivity of NGS-based approaches, we suggest that ImprintSeq might be offered at reference centres in case of ImpDis patients with unusual phenotypes but MLID negative by conventional tests. By WES, additional MLID causes than the already known maternal effect variants could not be identified, neither in the patients nor in the maternal exomes. In cases with negative WES results, it is currently unclear to what extent either environmental factors or undetected genetic variants contribute to MLID.

ABCC1 polymorphisms in anthracycline-induced cardiotoxicity in childhood acute lymphoblastic leukaemia.

Anthracyclines are potent cytostatic drugs, the correct dosage being critical to avoid possible cardiac side effects. ABCC1 [ATP-binding cassette, sub-family C, member 1; also denoted as MRP1 (multidrug resistance-associated protein 1)] is expressed in the heart and takes part in the detoxification and protection of cells from the toxic effects of xenobiotics, including anthracyclines. Our objective was to search for associations between LV (left ventricular) function and single-nucleotide polymorphisms of the ABCC1 gene in children receiving anthracycline chemotherapy. Data of 235 paediatric patients with acute lymphoblastic leukaemia was analysed. Patients were followed-up by echocardiography (median follow-up 6.3 years). Nine polymorphisms in the ABCC1 gene were genotyped. The ABCC1 rs3743527TT genotype and rs3743527TT­rs246221TC/TT genotype combination were associated with lower LVFS (left ventricular fractional shortening) after chemotherapy. The results suggest that genetic variants in the ABCC1 gene influence anthracycline-induced LV dysfunction.

Microdeletions in 1q21 and 8q12.1 depict two additional molecular subgroups of Silver-Russell syndrome like phenotypes.

BACKGROUND: Silver-Russell syndrome (SRS) is a genetic disorder characterized by intrauterine and postnatal growth restriction, relative macrocephaly at birth, body asymmetry and typical facial features. Clinical and molecular heterogeneity is described in SRS. Common causes are loss of methylation of the imprinting center 1 in 11p15 and maternal uniparental disomy of chromosome 7. Other genetic alterations include disturbances of imprinted regions in 14q32, 7q32 and 11p15 as well as submicroscopic deletions and duplications. Single nucleotide variants in genes like IGF2, HMGA2, PLAG1, CDKN1C have also been identified in patients with SRS phenotypes. However, routine molecular diagnostics usually focus on 11p15 and chromosome 7, while less frequent causes are not systematically addressed. RESULTS: Here we report two patients with SRS features in which molecular karyotyping revealed microdeletions in 1q21 and 8q12.1 respectively. In a 3.5-year-old girl with postnatal growth restriction, feeding difficulties, relative macrocephaly and distinct SRS features a 2 Mb deletion in 1q21.1q21.2 was identified. Our second case is a 1.5-year-old boy with intrauterine and postnatal growth restriction, feeding difficulties and distinct facial features with a 77 kb deletion in 8q12.1 affecting PLAG1 as the only protein-encoding gene with known function. CONCLUSIONS: The 1q21 region has not yet been assigned as an SRS region, although six patients with the same deletion and SRS features including relative macrocephaly have been described before. This new case adds to the evidence that distal 1q21 should be annotated as an SRS candidate region. The PLAGL1 alteration is the smallest deletion in 8q12.1 ever reported in a patient with SRS phenotype and it finally confirms that PLAG1 is the SRS causing gene in 8q12.1. To increase the diagnostic yield in patients with suspected SRS, we recommend both molecular karyotyping and next generation sequencing-based approaches.

Clinical evaluation of rare copy number variations identified by chromosomal microarray in a Hungarian neurodevelopmental disorder patient cohort.

BACKGROUND: Neurodevelopmental disorders are genetically heterogeneous pediatric conditions. The first tier diagnostic method for uncovering copy number variations (CNVs), one of the most common genetic etiologies in affected individuals, is chromosomal microarray (CMA). However, this methodology is not yet a routine molecular cytogenetic test in many parts of the world, including Hungary. Here we report clinical and genetic data of the first, relatively large Hungarian cohort of patients whose genetic testing included CMA. METHODS: Clinical data were retrospectively collected for 78 children who were analyzed using various CMA platforms. Phenotypes of patients with disease-causing variants were compared to patients with negative results using the chi squared/Fisher exact tests. RESULTS: A total of 30 pathogenic CNVs were identified in 29 patients (37.2%). Postnatal growth delay (p = 0.05564), pectus excavatum (p = 0.07484), brain imaging abnormalities (p = 0.07848), global developmental delay (p = 0.08070) and macrocephaly (p = 0.08919) were more likely to be associated with disease-causing CNVs. CONCLUSION: Our results allow phenotypic expansion of 14q11.2 microdeletions encompassing SUPT16H and CHD8 genes. Variants of unknown significance (n = 24) were found in 17 patients. We provide detailed phenotypic and genetic data of these individuals to facilitate future classification efforts, and spotlight two patients with potentially pathogenic alterations. Our results contribute to unraveling the diagnostic value of rare CNVs.