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Neurofibromatosis type-1 is a genetic disorder caused by loss-of-function variants in the tumor-suppressor NF1. Approximately 4% to 11% of neurofibromatosis type-1 patients have a NF1 locus complete deletion resulting from nonallelic homologous recombination between low copy repeats. Codeleted genes probably account for the more severe phenotype observed in NF1-deleted patients. This genotype-phenotype correlation highlights the need for a detailed molecular description. A droplet digital PCR (ddPCR) set along the NF1 locus was designed to delimitate the three recurrent NF1 deletion breakpoints. The ddPCR was tested in 121 samples from nonrelated NF1-deleted patients. Classification based on ddPCR versus multiplex ligation-dependent probe amplification (MLPA) was compared. In addition, microsatellites were analyzed to identify parental origin of deletions. ddPCR identified 77 type-1 (64%), 20 type-2 (16%), 7 type-3 (6%), and 17 atypical deletions (14%). The results were comparable with MLPA, except for three atypical deletions misclassified as type-2 using MLPA, for which the SUZ12 gene was not deleted. A significant maternal bias (25 of 30) in the origin of deletions was identified. This study proposes a fast and efficient ddPCR quantification to allow fine NF1 deletion classification. It indicates that ddPCR can be implemented easily into routine diagnosis to complement the techniques dedicated to NF1 point variant identification. This new tool may help unravel the genetic basis conditioning phenotypic variability in NF1-deleted patients and offer tailored genetic counseling., Competing Interests: Disclosure Statement None declared., (Copyright © 2024 Association for Molecular Pathology and American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Neurofibromatosis type 1 (NF1) is a frequent autosomal dominant genetic disorder that predisposes to the development of benign and malignant tumors. Mutation of the NF1 gene affects the RAS-MAPK signaling pathway and leads to a dysfunction in cell proliferation and induces tumor development. Epidemiology of cancer in children with NF1 is very different from the general pediatric population, which requires regular and specific monitoring. Neurofibroma is the most frequent benign tumor. It can be very invalidating depending on the size and location of the tumor. Currently, there is no specific treatment for these tumors. The most frequent malignancies in children with NF1 are leukemias, rhabdomyosarcomas, malignant peripheral nerve sheath tumors and gliomas. The treatment of these tumors should consider the risk of second cancers induced by radio- and chemotherapy. We report on the case of a 5-year-old boy with NF1 developing two tumors., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Background: Neurofibromatosis 1 (NF1) belongs to the autosomal dominant neurocutaneous disorders' group, which mainly includes NF1 and NF2, tuberous sclerosis, von Hippel-Lindau disease and Cerebral Cavernous Malformations (CCMs). NF1 has a major impact on the nervous system, eye, skin, bone or cardiovascular system. Cerebrovascular lesions have been reported in NF1 including aneurysm, pseudoaneurysm, arteriovenous malformations, vascular stenosis or occlusion and Moya moya syndrome., Objective: To report a case of an NF1 patient with multiple CCMs., Observation: A 47-year-old man with café-au-lait skin lesions, countless cutaneous neurofibromas, short stature and scoliosis was admitted for progressive spinal cord compression due to histologically proven neurofibroma. Systematic cerebral MRI screening including gradient echo sequences showed multiple asymptomatic CCMs. Screening of CCM1, CCM2 and CCM3 genes was negative while a deleterious frameshift mutation was identified in NF1 gene., Conclusion: While single CCM can occur in NF1 patients following radiation exposure, they are only rarely reported in non-irradiated NF1 brain. Even if it could be a fortuitous association, plausible links and explanations exist. If cerebral MRI can be systematic in NF1 to detect asymptomatic gliomas, used protocols in neuroradiology do not usually include gradient echo sequences, the most sensitive test for CCM detection, leading possibly to failure to detect these vascular lesions. More reports having this combination and further investigations of NF1 families will certainly provide a better understanding of links between these 2 phakomatoses, as recently reported with "multiple meningiomas" phenotype associated with multiple CCMs in patients with CCM3 gene mutations or café-au-lait skin lesions in CCM1 mutation carriers., (Copyright © 2015. Published by Elsevier B.V.)

Neurofibromatosis type 1 (NF1) is an autosomal dominant, multi-system, neurocutaneous disorder that predisposes to the development of benign and malignant tumors with a birth incidence rate of 1 in 2500-3000. 50% of cases are sporadic. The diagnosis is exclusively based on clinical assessment with clinical diagnostic criteria such as café-au-lait spots, neurofibromas, axillary or groin freckling, Lisch nodules, optic pathway glioma, bony dysplasia and first-degree relative with NF1. We report a family with NF1 in which two members presented atypical clinical features in addition to the classical diagnostic criteria. Three relatives affected by NF1, a father and two of his three sons, are described. The clinical diagnosis was originally worn in all three cases, with the association many spots café-au -lait over the entire body and some axillary freckling as well as first-degree relative. One case presented an Acute Myeloid Leukemia (AML) type 2 at 10 years of age diagnosed before the revelation of bicytopenia associated pallor and isolated asthenia. A second case presented a nephrotic syndrome at 4 years of age due to the association of hydrops with headache and asthenia. Direct sequencing of NF1 led to identify the familial mutation, a previously unreported heterozygous missense mutation c.3443C > A, p.Ala1148Glu in exon 20 which segregated with all three affected patients. The family described in this report confirms the high clinical variability of NF1, even intrafamilial, and raises the question as to whether rare features such as AML and nephrotic syndrome are associated with NF1. Some NF1 patients presenting glomerular diseases or AML have rarely been reported, but due to the small number of cases described the mechanisms underlying these associations are poorly understood. However, it seems important to be aware of the possible occurrence of nephritic syndrome and/or malignant blood diseases in NF1 patients., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

Background & Aims: Polymorphisms in the region of the interleukin (IL)28B gene have been associated with pegylated-interferon (PEG-IFN) and ribavirin treatment response mainly in genotype 1 HCV infections. However, there are few data on HCV genotype 4 (HCV-4) infection. We evaluated, in a unique well-characterized cohort of HCV-4 patients, the association of IL28B polymorphism with response to treatment or liver disease severity., Methods: This study included 164 HCV-4 patients from different ethnic groups (Egyptian, European, and Sub-Saharan African). Among these patients, 82 were studied for response and 160 for disease severity. Free DNA extracted from all the 164 patient's serum samples was analyzed by direct sequencing of the SNP rs12979860 of IL28B. Genetic and bio-clinical features from patients having sustained virological response (43 SVR patients) and from those who did not respond to treatment or had a relapse after the end of the treatment (39 NR patients) were compared. IL28B polymorphism was compared between the 78 patients with mild fibrosis (Metavir score F0-F1) and the 82 with advanced fibrosis (F2-F4)., Results: Our data showed a better treatment response rate of the C allele of the IL28B gene SNP rs12979860 (p=0.0008). The response rates were 81.8%, 46.5%, and 29.4% for genotype CC, CT, and TT, respectively. No significant relationship was found between rs12979860 and the severity of the disease., Conclusions: The SNP rs12979860 is strongly associated with SVR in patients infected with HCV-4, but not with liver disease severity. Analysis of IL28B genotype might be used to guide treatment for these patients., (Copyright © 2011 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.)

In 5% to 10% of cases, neurofibromatosis type 1 is caused by microdeletions scattered across the entire NF1 gene and various neighboring genes. The phenotype appears to be more severe in patients with NF1 microdeletions than in patients with NF1 single point mutations. We have developed a new method for detecting and characterizing NF1 microdeletions based on a custom high-resolution oligonucleotide array comparative genomic hybridization by using the custom 8x15K Agilent array format. The array comprised a total of 14,207 oligonucleotide probes spanning the whole of chromosome 17, including 12,314 probes spanning an approximately 8 Mb interval surrounding the NF1 locus. We validated this approach by testing NF1 microdeleted DNA samples previously characterized by means of microsatellites and real-time PCR methods. Our array comparative genomic hybridization provided enough information for subsequent long-range PCR and nucleotide sequencing of the microdeletion endpoints. Unlike previously described methods, our array comparative genomic hybridization was able to unambiguously differentiate between the three types of microdeletions (type I, type II, and atypical) and to characterize atypical microdeletions. Further comparative studies of patients with well-characterized genotypes and phenotypes and different microdeletions sizes and breakpoints will help determine whether haploinsufficiency of deleted genes and/or genes rearrangements influence clinical outcomes.

Background/aims: To evaluate the efficacy of peginterferon alfa-2b and ribavirin in unselected consecutive patients with chronic hepatitis C, treated outside of trials, who were relapsers or non-responders to interferon and ribavirin combination., Methods: One hundred and fifty-four patients were evaluated. There were 101 non-responders and 53 relapsers to standard combination therapy. Patients were retreated with peginterferon alfa-2b 1.5 microg/kg/wk plus ribavirin 1000-1200 mg/day during 48 weeks., Results: Forty-four patients (28.6%) achieved sustained virological response (SVR). Rapid (week 4) and early (week 12) virological response had high negative predictive values of SVR (94% and 97%, respectively); however positive predictive values were relatively low (52% and 49%, respectively). Relapsers had higher SVR rates (58.5%) than non-responders (13%) p<0.0001. In non-responders, SVR raised to 50% in patients with genotype non-1 and mild or moderate fibrosis. In multivariate analysis, predictors of SVR were: relapse after interferon plus ribavirin combination, mild or moderate fibrosis, genotype non-1 and baseline viral load <2 million copies/ml., Conclusions: Relapsers to interferon plus ribavirin therapy, and non-responders with genotype non-1 and mild or moderate fibrosis, achieved a relatively high SVR rate following retreatment with peginterferon plus ribavirin. Early viral kinetics had a high negative predictive value of SVR.

Using a protein truncation assay, we have identified a new mutation in the neurofibromatosis type 1 (NF1) gene that causes a severe defect in NF1 pre-mRNA splicing. The mutation, which consists of a G to A transition at position +1 of the 5' splice site of exon 12a, is associated with the loss of both exons 11 and 12a in the NF1 mRNA. Through the use of in vivo and in vitro splicing assays, we show that the mutation inactivates the 5' splice site of exon 12a, and prevents the definition of exon 12a, a process that is normally required to stimulate the weak 3' splice site of exon 12a. Because the 5' splice site mutation weakens the interaction of splicing factors with the 3' splice site of exon 12a, we propose that exon 11/exon 12a splicing is also compromised, leading to the exclusion of both exons 11 and 12a. Our results provide in vivo support for the importance of the exon definition model during NF1 splicing, and suggest that the NF1 region containing exons 11 and 12a plays an important role in the activity of neurofibromin., (Copyright 2001 Academic Press.)

Sequencing the complete factor IX gene of 2 sisters with hemophilia B with different phenotypes and no family history of hemorrhagic diathesis revealed a common 5' splice site mutation in intron 3 (T6704C) in both and an additional missense mutation (I344T) in one. The presence of dysfunctional antigen in the latter strongly suggested that these mutations are in trans. Neither mutation was found in leukocyte DNA from the asymptomatic parents, but the mother was in somatic mosaicism for the shared splice site mutation. This case illustrates the importance of defining the phenotype and considering somatic mosaicism in sporadic cases. It underlines the limitations of complete gene sequencing for the detection of mosaicism and has implication for genetic counseling. (Blood. 2000;96:1585-1587)

Bacterial DNA helicase RuvB protein is an essential component in homologous recombination and DNA double-strand break repair. Here, we report the gene structure of TIP49b/RUVBL2, a second putative human homologue of the bacterial RuvB gene. This gene contains 15 exons and 14 introns. The TIP49b/RUVBL2 open reading frame encodes a protein of 463 amino acids, showing 43% identity with the RUVBL1 protein. The TIP49b/RUVBL2 gene is physically linked to the human CGB/LHB gene cluster on chromosome 19q13.3. Genomic sequence analysis revealed that the TIP49b/RUVBL2 gene is very close (55 nucleotides in length) to the LHB gene, in the opposite orientation. The very close co-location of the mouse homologues of the human TIP49b/RUVBL2 and LHB genes was also conserved on mouse chromosome 7. Co-ordinated transcriptional regulation between the TIP49b/RUVBL2 and LHB genes was not observed. TIP49b/RUVBL2, like RUVBL1, was expressed ubiquitously in all human tissues examined and more strongly in testis. As TIP49b/RUVBL2 is expected to be involved in recombination repair and is located in a chromosome region frequently amplified in breast cancer, we quantified TIP49b/RUVBL2 gene expression by using real-time quantitative RT-PCR in a series of breast tumour samples. None of the tumour samples showed an altered TIP49b/RUVBL2 transcription level relative to normal breast tissue.

A five-generation family is here reported in which several members developed malignant melanoma, dysplastic naevi, astrocytoma in all grades, benign or malignant schwannoma, neurofibroma, or meningioma in a single instance. Significant cosegregation of skin and nervous tumours, preclusion of allelism to type 1 neurofibromatosis and phenotypic departure from known syndromes of hereditary proneness to cancer make one suggest an original familial predisposition to both malignant melanoma and central/peripheral nervous tumours.

Antithrombin III (AT III) type I deficiencies are characterized by a 50% decrease of both immunoreactive and functional protein and carry a high risk of thrombotic complication. We have studied the molecular basis for such deficiencies by asymmetric polymerase chain reaction amplification and direct sequencing of the seven exons and of the intron-exon junction of the AT III gene. Three different mutations were observed in the exon IV: a 4-bp deletion, a 2-bp deletion, and a nucleotide insertion. Each of these mutations results in a frameshift introducing premature stop codons at positions 313, 309, and 232, respectively. These results were confirmed by dot-blot analysis with allele-specific oligonucleotide probes. Furthermore, no mutation was observed in the other six exons. The comparison of the type of mutations observed by our group in six cases of type I deficiencies and in 16 cases of type II heparin binding site variants deficiencies suggests that the former are caused by heterogeneous molecular abnormalities while the latter are caused by recurrent missense mutations.

An increased synthesis of fetal hemoglobin in adult life is a common feature of the genetically determined severe disorders like beta thalassemia and sickle cell anemia. A continued synthesis of fetal hemoglobin in adults is also characteristic of clinical or subclinical syndromes like respectively delta beta thalassemia or hereditary persistence of fetal hemoglobin (HPFH). These disorders are highly heterogeneous with respect to their molecular defects as well as to the composition of Hb F. We report here a novel case of hereditary persistence of fetal hemoglobin in heterozygous state discovered by chance, in a young perfectly healthy french man. The gamma chain of his fetal hemoglobin was almost entirely composed of G gamma chains. Molecular analysis of the DNA revealed the existence of triplicated gamma genes on one chromosome with the genotype arrangement of G gamma-G gamma-A gamma. A polymorphic Xmn I restriction site (at position -158 5' to the cap site) was present in 5' of both of these G gamma genes. The presence of this site in front of G gamma gene had previously been shown to be associated both with high G gamma phenotype constitutively and also with high fetal hemoglobin level only in case of anemic stress. In the absence of any anemic stress in this individual, the constitutive increase of both fetal hemoglobin and G gamma chains could be due to the presence of a chromosome with triplicated arrangement of gamma genes. The classical triplication (G gamma-A gamma-G gamma-A gamma) does not result in HPFH phenotype.(ABSTRACT TRUNCATED AT 250 WORDS)

A rare association of three haemoglobin defects, viz: traits for deletion form of alpha-thalassaemia, beta-thalassaemia, and sickle cell gene, in a family of French West Indies origin, was studied both at phenotype and genotype levels. In this sickle cell beta-thalassaemia, interacting alpha-thalassaemia is shown to influence the foetal haemoglobin expression. A reverse relationship between the foetal haemoglobin level and the number of alpha genes was observed.