De Novo p.Asp3368Gly Variant of Dystrophin Gene Associated with X-Linked Dilated Cardiomyopathy and Skeletal Myopathy: Clinical Features and In Silico Analysis

Dystrophin (DMD) gene mutations are associated with skeletal muscle diseases such as Duchenne and Becker Muscular Dystrophy (BMD) and X-linked dilated cardiomyopathy (XL-DCM). To investigate the molecular basis of DCM in a 37-year-old woman. Clinical and genetic investigations were performed. Genetic testing was performed with whole exome sequencing (WES) using the Illumina platform. According to the standard protocol, a variant found by WES was confirmed in all available members of the family by bi-directional capillary Sanger resequencing. The effect of the variant was investigated by using an in silico prediction of pathogenicity. The index case was a 37-year-old woman diagnosed with DCM at the age of 33. A germline heterozygous A>G transversion at nucleotide 10103 in the DMD gene, leading to an aspartic acid-glycine substitution at the amino acid 3368 of the DMD protein (c.10103A>G p.Asp3368Gly), was identified and confirmed by PCR-based Sanger sequencing of the exon 70. In silico prediction suggests that this variant could have a deleterious impact on protein structure and functionality (CADD = 30). The genetic analysis was extended to the first-degree relatives of the proband (mother, father, and sister) and because of the absence of the variant in both parents, the p.Asp3368Gly substitution was considered as occurring de novo. Then, the direct sequencing analysis of her 8-year-old son identified as hemizygous for the same variant. The young patient did not present any signs or symptoms attributable to DCM, but reported asthenia and presented with bilateral calf hypertrophy at clinical examination. Laboratory testing revealed increased levels of creatinine kinase (maximum value of 19,000 IU/L). We report an early presentation of dilated cardiomyopathy in a 33-year-old woman due to a de novo pathogenic variant of the dystrophin (DMD) gene (p.Asp3368Gly). Genetic identification of this variant allowed an early diagnosis of a skeletal muscle disease in her son.

Pembrolizumab-Induced Psoriasis in Metastatic Melanoma: Activity and Safety of Apremilast, a Case Report

Background

Immune checkpoint inhibitors targeting cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), programmed death-1 receptor (PD-1), and programmed death-1 receptor and its ligand (PD-L1) increased the survival of patients affected by metastatic malignant melanoma. Due to their mechanism of action, these drugs are associated with a unique toxicity profile. Indeed, immune-related adverse events (irAEs) present a wide clinical spectrum representing the Achilles' heel of immunotherapy. Overall, cutaneous toxicities are among the most common irAEs. Immunomodulatory drugs are used for the management of irAEs and can theoretically lead to tumor escape.

Case Presentation

We report the case of a 75-year-old man with metastatic melanoma receiving the anti-PD1 Pembrolizumab therapy. After 10 treatment cycles, the patient came to our clinic with itchy psoriatic manifestations widespread >30% of the body surface [12.3 Psoriasis Area and Severity Index (PASI) score] that negatively impacted on the patient's quality of life and compliance with immunotherapy. Additionally, he had no positive personal history of psoriasis. Given the severity of the cutaneous manifestations, in a multidisciplinary approach, Apremilast (an oral small molecule PDE4 inhibitor) was started. Furthermore, Pembrolizumab was interrupted for 4 weeks until the improvement of skin lesions and the disappearance of itching. Immunosuppressive methylprednisolone therapy was initiated with a dose of 16 mg/die; then, this initial dose was progressively reduced until discontinuation. After 10 months, the patient had a good general clinical condition with psoriasis complete remission. Moreover, positron emission tomography (PET) and computed tomography (CT) scans showed complete response by immune Response Evaluation Criteria in Solid Tumors (iRECIST).

Conclusion

To the best of our knowledge, this is the first report on the safety and efficacy of Apremilast for the treatment of immunotherapy-induced psoriasis in metastatic melanoma.

HMGB1 Is Increased by CFTR Loss of Function, Is Lowered by Insulin, and Increases In Vivo at Onset of CFRD

CONTEXT

Cystic fibrosis-related diabetes (CFRD) is associated with worsening of inflammation and infections, and the beginning of insulin treatment is debated.

OBJECTIVES

To verify high-mobility group box 1 protein (HMGB1) levels in CF patients according to glucose tolerance state, and analyze relationships with insulin secretion and resistance. To verify, in an in vitro model, whether HMGB1 gene expression and protein content were affected by insulin administration and whether these changes were dependent on CF transmembrane conductance regulator (CFTR) loss of function.

PATIENTS AND METHODS

Forty-three patients in stable clinical conditions and 35 age- and sex-matched controls were enrolled. Glucose tolerance was established in patients based on a 5 point oral glucose tolerance test (OGTT). Fasting glucose to insulin ratio (FGIR), HOMA-IR index, whole-body insulin sensitivity index (WIBISI), and the areas under the curve for glucose (AUCG) and insulin (AUCI) were calculated. HMGB1 was assayed in serum, in cell lysates and conditioned media using a specific ELISA kit. For the in vitro study we used CFBE41o- cells, homozygous for the F508del mutation, and 16HBE14o- as non-CF control. HMGB1 gene expression was studied by real-time RT-PCR. Cells were stimulated with insulin at 2.5 and 5 ng/mL. The CFTR inhibitor 172 and CFTR gene silencing were used to induce CFTR loss of function in 16HBE14o- cells.

RESULTS

HMGB1 levels were increased at onset of CFRD (5.04 ± 1.2 vs 2.7 ± 0.3 ng/mL in controls; P < .05) and correlated with FGIR (R = +0.43; P = .038), and AUCI (R = +0.43; P = .013). CFTR loss of function in the 16HBE14o- cells increased HMGB1 and was lowered by insulin.

CONCLUSION

HMGB1 was increased in CF patients with deranging glucose metabolism and showed relationships with indexes of glucose metabolism. The increase in HMGB1 was related to CFTR loss of function, and insulin lowered HMGB1. Further research is required to verify whether HMGB1 could potentially be a candidate marker of onset of CFRD and to establish when to start insulin treatment.

TRPC6 mutations in children with steroid-resistant nephrotic syndrome and atypical phenotype

BACKGROUND AND OBJECTIVES

Mutations in the TRPC6 gene have been recently identified as the cause of late-onset autosomal-dominant focal segmental glomerulosclerosis (FSGS). To extend the screening, we analyzed TRPC6 in 33 Italian children with sporadic early-onset SRNS and three Italian families with adult-onset FSGS.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

TRPC6 mutation analysis was performed through PCR and sequencing. The effects of the detected amino acid substitutions were analyzed by bioinformatics tools and functional in vitro studies. The expression levels of TRPC6 and nephrin proteins were evaluated by confocal microscopy.

RESULTS

Three heterozygous missense mutations (c.374A>G_p.N125S, c.653A>T_p.H218L, c.2684G>T_p.R895L) were identified. The first new mutation, p.H218L, was found in a 18-year-old boy who presented a severe form of FSGS at the age of 8 years. The second, p.R895L, a new de novo mutation, was identified in a girl with collapsing glomerulosclerosis at the age of 2 years. The former mutation, p.N125S, was found in two siblings with early-onset steroid-resistant nephrotic syndrome (SRNS) at the ages of 4 and 14 years. Renal immunofluorescence revealed upregulated expression of TRPC6 and loss of nephrin in glomeruli. The intracellular calcium concentrations were significantly higher in the cells expressing all mutant TRPC6 channels compared with cells expressing wild-type TRPC6.

CONCLUSIONS

Our findings suggest that TRPC6 variants can also be detected in children with early-onset and sporadic SRNS (4 of 33 patients). Moreover, in one patient a new de novo TRPC6 mutation was associated with a rare severe form of childhood collapsing glomerulosclerosis with rapid progression to uremia.

Cord blood in vitro expanded CD41 cells: identification of novel components of megakaryocytopoiesis

BACKGROUND

Megakaryopoiesis represents a multi-step, often unclear, process leading to commitment, differentiation, and maturation of megakaryocytes (MKs) that release platelets.

AIM

To identify the novel genes that might help to clarify the molecular mechanisms of megakaryocytopoiesis and be regarded as potential candidates of inherited platelet defects, global gene expression of hematopoietic lineages was carried out.

METHODS

Human cord blood was used to purify CD34+ stem cells and in vitro expand CD41+ cells and burst-forming unit-erythroid (BFU-E). We investigated the expression profiles of these three hematopoietic lineages in the Affymetrix system and selected genes specifically expressed in MKs by comparing transcripts of the different lineages using the dchip and pam algorithms.

RESULTS

A detailed characterization of MK population showed that 99% of cells expressed the CD41 antigen whereas 73% were recognizable as terminally differentiated fetal MKs. The profile of these cells was compared with that of CD34+ cells and BFU-E allowing us to select 70 transcripts (MK-core), which represent not only the genes with a well-known function in MKs, but also novel genes never detected or characterized in these cells. Moreover, the specific expression was confirmed at both RNA and protein levels, thus validating the 'MK-core' isolated by informatics tools.

CONCLUSIONS

This is a global gene expression that for the first time depicts a well-characterized population of cord blood-derived fetal MKs. Novel genes have been detected, such as those encoding components of the extracellular matrix and basal membrane, which have been found in the cytoplasm of Mks, suggesting that new physiological aspects of MKs should be studied.

Microcytic anemia and hepatic iron overload in a child with compound heterozygous mutations in DMT1 (SCL11A2)

Divalent metal transporter 1 (DMT1) mediates apical iron uptake in duodenal enterocytes and iron transfer from the transferrin receptor endosomal cycle into the cytosol in erythroid cells. Both mk mice and Belgrade rats, which carry an identical DMT1 mutation, exhibit severe microcytic anemia at birth and defective intestinal iron use and erythroid iron use. We report the hematologic phenotype of a child, compound heterozygote for 2 DMT1 mutations, who was affected by severe anemia since birth and showed hepatic iron overload. The novel mutations were a 3-bp deletion in intron 4 (c.310-3_5del CTT) resulting in a splicing abnormality and a C>T transition at nucleotide 1246(p. R416C). A striking reduction of DMT1 protein in peripheral blood mononuclear cells was demonstrated by Western blot analysis. The proband required blood transfusions until erythropoietin treatment allowed transfusion independence when hemoglobin levels between 75 and 95 g/L (7.5 and 9.5 g/dL) were achieved. Hematologic data of this patient at birth and in the first years of life strengthen the essential role of DMT1 in erythropoiesis. The early onset of iron overload indicates that, as in animal models, DMT1 is dispensable for liver iron uptake, whereas its deficiency in the gut is likely bypassed by the up-regulation of other pathways of iron use.

Spectrum of PTCH mutations in Italian nevoid basal cell-carcinoma syndrome patients: identification of thirteen novel alleles

The nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant genetic disease characterized by numerous basal cell carcinomas, odontogenic keratocysts of the jaws, palmar and plantal pits, skeletal abnormalities, and calcification of the falx cerebri. The gene responsible for this syndrome is the PTCH tumor suppressor gene encoding for the sonic hedgehog receptor. In this paper, we report thirteen novel mutations identified in the first screening of NBCCS patients in Italy. Except for p.T230P and p.F505_L506delinsLR, all the other mutations are predicted to determine a premature truncation of the protein.

Spectrum ofUGT1A1 mutations in Crigler-Najjar (CN) syndrome patients: identification of twelve novel alleles and genotype-phenotype correlation

Crigler-Najjar syndrome types I and II (CN1 and CN2) are usually inherited as autosomal recessive conditions and are characterized by non-hemolytic unconjugated hyperbilirubinaemia. CN1 is the most severe form, associated with the absence of hepatic bilirubin-uridinediphosphoglucuronate glucuronosyltransferase (UGT1A1) activity. CN2 presents intermediate levels of hyperbilirubinaemia as a result of an incomplete deficiency of hepatic UGT1A1 activity. Here, we present the analysis of UGT1A1 gene in 31 unrelated Crigler-Najjar (CN) syndrome patients. This analysis allowed us to identify 22 mutations, 12 of which were not previously described, expanding the spectrum of known UGT1 mutations to 77. Novel mutations, considered pathogenic, including one nonsense mutation, two altered splice sites, one single base deletion and nine missense mutations were identified in coding exons of the UGT1A1gene and flanking introns. Several novel missense mutations localize in critical domain of UGT1A1 enzyme. In addition, the evaluation of Gilbert-type promoter of UGT1A1in Crigler-Najjar (CN) syndrome patients was performed. The polymorphisms of the promoter region can modify the UGT1A1 mutation phenotype. This study represents the molecular characterization of the largest cohort of Italian Crigler-Najjar Gilbert syndrome patients studied so far; increase the mutational spectrum of UGT1A1 allelic variants worldwide and provide a new insight useful for clinical diagnosis and genetic counseling.

Mutations in MYH9 result in the May-Hegglin anomaly, and Fechtner and Sebastian syndromes. The May-Heggllin/Fechtner Syndrome Consortium

The autosomal dominant, giant-platelet disorders, May-Hegglin anomaly (MHA; MIM 155100), Fechtner syndrome (FTNS; MIM 153640) and Sebastian syndrome (SBS), share the triad of thrombocytopenia, large platelets and characteristic leukocyte inclusions ('Döhle-like' bodies). MHA and SBS can be differentiated by subtle ultrastructural leukocyte inclusion features, whereas FTNS is distinguished by the additional Alport-like clinical features of sensorineural deafness, cataracts and nephritis. The similarities between these platelet disorders and our recent refinement of the MHA (ref. 6) and FTNS (ref. 7) disease loci to an overlapping region of 480 kb on chromosome 22 suggested that all three disorders are allelic. Among the identified candidate genes is the gene encoding nonmuscle myosin heavy chain 9 (MYH9; refs 8-10), which is expressed in platelets and upregulated during granulocyte differentiation. We identified six MYH9 mutations (one nonsense and five missense) in seven unrelated probands from MHA, SBS and FTNS families. On the basis of molecular modelling, the two mutations affecting the myosin head were predicted to impose electrostatic and conformational changes, whereas the truncating mutation deleted the unique carboxy-terminal tailpiece. The remaining missense mutations, all affecting highly conserved coiled-coil domain positions, imparted destabilizing electrostatic and polar changes. Thus, our results suggest that mutations in MYH9 result in three megakaryocyte/platelet/leukocyte syndromes and are important in the pathogenesis of sensorineural deafness, cataracts and nephritis.

Characterization of copine VII, a new member of the copine family, and its exclusion as a candidate in sporadic breast cancers with loss of heterozygosity at 16q24.3

In a search for candidate tumor suppressor genes within a 650-kb common region of loss of heterozygosity (LOH) at 16q24.3 in breast cancer tissues, a 2.6-kb cDNA, named copine VII (CPNE7), was characterized. The gene is 2654 bp and codes for a 633-residue protein with high homology to the other members of the copine family, such as copine I, copine III, and N-copine. The predicted amino acid sequence contains two copies of a C2 domain in the N-terminus. Since these domains have been found in several membrane-binding proteins involved in different intracellular processes, copine VII was viewed as a potential tumor suppressor gene. Mutation analysis was carried out by single-strand conformation polymorphism analysis of 18 breast tumor tissue samples with ascertained LOH on chromosome 16q24.3. Since only two polymorphisms were identified, no evidence was found to indicate that copine VII is the tumor suppressor gene at 16q24.3 involved in breast cancer.

Fine exon-intron structure of the Fanconi anemia group A (FAA) gene and characterization of two genomic deletions

Fanconi anemia (FA) is a genetically heterogeneous disease with at least eight genes on the basis of complementation groups (FAA to FAH). The analysis of the FAA gene in patients suggested the existence of deletions, none of which have thus far been characterized at the genomic level. A detailed restriction map of the FAA gene with the fine localization of its 43 exons is reported in this paper. We also describe the first two genomic deletions, one of 5.0 kb and another of at least 120 kb. The former was likely the result of a recombination between related Alu sequences. Since these interspersed repeats could generate deletions and insertions by mispairing, rearrangements of this gene are a possibility in those FA families in which FAA mutations have not been identified.

Molecular basis of Fanconi anemia

BACKGROUND AND OBJECTIVE

Fanconi anemia (FA) is an autosomal recessive disease characterized by pancytopenia, congenital malformation and high predisposition to developing malignancies. The phenotypical heterogeneity is associated with genetic heterogeneity: at least 8 complementation groups (FA-A to FA-H) have been identified, each group presumably corresponding to a separate disease gene (FAA to FAH). The FAA and FAC genes, which account for 75-80% of the patients, have been cloned. Their protein products have no significant homology to any known protein, or to each other, and may therefore represent elements of a new pathway. This review describes some of the recent contributions to the understanding of the molecular basis of FA.

EVIDENCE AND INFORMATION SOURCES

The authors of the present review have been working in the field of FA for several years. In the present review they have critically examined articles published in journals covered by the Science Citation Index and Medline.

STATE OF ART AND PERSPECTIVE(S)

A variety of biochemical and cellular approaches have been used to determine the molecular defect of FA. Evidence for a possible role of the defective proteins in cell cycle regulation, apoptosis, or DNA stability have been reported. Recently, it has been demonstrated that FAA and FAC proteins bind each other and form a complex found in similar abundance in both cytoplasm and nucleus, suggesting a possible function in nucleus activities. Knowledge of the mutation spectrum occurring in the FA genes may contribute significantly to pathogenesis studies in FA and help to design mutation screening strategies. Further functional studies and the cloning of other FA genes will provide insights into the biological basis of FA and information for developing specific therapies for the disease.

Cyclodextrins for growth of Helicobacter pylori and production of vacuolating cytotoxin

Growth of Helicobacter pylori in liquid culture requires the addition of media supplements that often interfere with subsequent purification of bacterial antigens. In order to determine whether cyclodextrins can substitute for conventional H. pylori growth supplements, we cultured H. pylori in the presence of five commercially available cyclodextrins. The effect of these compounds on the production of the vacuolating cytotoxin antigen was evaluated. Several cyclodextrins supported flourishing growth and permitted the consistent production of vacuolating cytotoxin. These data suggest that Brucella broth supplemented with cyclodextrins is an improved medium for bacterial culture and industrial production of H. pylori antigens.