A Single Center Retrospective Review of Patients from Central Italy Tested for Melanoma Predisposition Genes.

BACKGROUND: Cutaneous malignant melanoma (CMM) is one of the most common skin cancers worldwide. CMM pathogenesis involves genetic and environmental factors. Recent studies have led to the identification of new genes involved in CMM susceptibility: beyond CDKN2A and CDK4, BAP1, POT1, and MITF were recently identified as potential high-risk melanoma susceptibility genes. OBJECTIVE: This study is aimed to evaluate the genetic predisposition to CMM in patients from central Italy. METHODS: From 1998 to 2017, genetic testing was performed in 888 cases with multiple primary melanoma and/or familial melanoma. Genetic analyses included the sequencing CDKN2A, CDK4, BAP1, POT1, and MITF in 202 cases, and of only CDKN2A and CDK4 codon 24 in 686 patients. By the evaluation of the personal and familial history, patients were divided in two clinical categories: "low significance" and "high significance" cases. RESULTS: 128 patients (72% belonging to the "high significance" category, 28% belonging to the "low significance" category) were found to carry a DNA change defined as pathogenic, likely pathogenic, variant of unknown significance (VUS)-favoring pathogenic or VUS. CONCLUSIONS: It is important to verify the genetic predisposition in CMM patients for an early diagnosis of further melanomas and/or other tumors associated with the characterized genotype.

Characterization of three novel pathogenic SLC40A1 mutations and genotype/phenotype correlations in 7 Italian families with type 4 hereditary hemochromatosis.

Mutations of SLC40A1 encoding ferroportin (Fpn), the unique cellular iron exporter, severely affect iron homeostasis causing type 4 hereditary hemochromatosis, an autosomal dominant iron overload condition with variable phenotypic manifestations. This disease can be classified as type 4A, better known as "ferroportin disease", which is due to "loss of function" mutations that lead to decreased iron export from cells, or as type 4B hemochromatosis, which is caused by "gain of function" mutations, conferring partial or complete resistance to hepcidin-mediated Fpn degradation. In this work, we discuss clinical and molecular findings on a group of patients in whom a SLC40A1 single copy missense variant was identified. Three novel variants, p.D181N, p.G204R and p.R296Q were functionally characterized. Fpn D181N and R296Q mutants can be classified as full or partial loss of function, respectively. Replacement of G204 with arginine appears to cause a more complex defect with impact both on iron export function and hepcidin sensitivity. This finding confirms the difficulty of predicting the effect of a mutation on the molecular properties of Fpn in order to provide an exhaustive explanation to the wide variability of the phenotype in type 4 hereditary hemochromatosis.

Hereditary hemochromatosis type 1 phenotype modifiers in Italian patients. The controversial role of variants in HAMP, BMP2, FTL and SLC40A1 genes.

Hereditary hemochromatosis (HH) is a heterogeneous disorder of iron metabolism. The most common form of the disease is Classic or type 1 HH, mainly caused by a biallelic missense p.Cys282Tyr (c.845G>A) mutation in the HFE gene. However, the penetrance of p.Cys282Tyr/p.Cys282Tyr genotype is incomplete in terms of both biochemical and clinical expressivity. Lack of penetrance is thought to be caused by several genetic and environmental factors. Recently, a lot of evidences on HH genetic modifiers were produced, often without conclusive results. We investigated 6 polymorphisms (rs10421768 in HAMP gene, rs235756 in BMP2 gene, rs2230267 in FTL gene, rs1439816 in SLC40A1 gene, rs41295942 in TFR2 gene and rs2111833 in TMPRSS6 gene) with uncertain function in order to further evaluate their role in an independent cohort of 109 HH type 1 patients. Our results make it likely the role of rs10421768, rs235756, rs2230267 and rs1439816 polymorphisms, respectively in HAMP, BMP2, FTL and SLC40A1 genes in HH expressivity. In addition, previous and our findings support a hypothetical multifactorial model of HH, characterized by a principal gene (HFE in HH type 1) and minor genetic and environmental factors that still have to be fully elucidated.

TFR2-related hereditary hemochromatosis as a frequent cause of primary iron overload in patients from Central-Southern Italy.

OBJECTIVE: Hereditary hemochromatosis (HH) is a common Mendelian disorder of iron metabolism. Eighty percent of northern Europeans descendant HH patients carry the same mutation (p.C282Y) in the HFE gene. Simultaneously, due to a founder effect, its frequency varies considerably between different populations. In Central-Southern Italy the prevalence of p.C282Y mutation is low and in several patients the disease has different causes. Four additional rarer forms have been described. Type 3 HH has been reported in about 50 families and no more than 30 TFR2 pathogenic mutations have been globally identified. The aim of this study is to assess the TFR2 role in non-HFE HH pathogenesis. STUDY DESIGN AND SETTING: TFR2 sequence analysis was performed on 45 Italian patients without HFE mutations. RESULTS: This study revealed TFR2 biallelic pathogenic mutations in 7/45 (15.6%) individuals. Moreover monoallelic TFR2 deleterious defects (18%) or polymorphisms with unclear meaning (36%) were identified. Besides, we recognized 10 novel variants and 9 described changes. CONCLUSION: We believe this to be the largest series of type 3 HH patients described so far. Present findings support the hypothesis of a main role of the TFR2 gene in HH pathogenesis in those regions, such as Central-Southern Italy, where the p.C282Y frequency is low.

Late diagnosis of lateral meningocele syndrome in a 55-year-old woman with symptoms of joint instability and chronic musculoskeletal pain.

Lateral meningocele syndrome (LMS) is a rare hereditary connective tissue disorder characterized by pan-spinal meningoceles, specific facial dysmorphism, skeletal and soft tissue abnormalities, and hypotonia and/or muscle weakness. LMS has been observed in eleven patients with two instances of vertical transmission, and seven sporadic cases with an age at diagnosis ranging from 25 months to 33 years. We report on a further observation of LMS in a 55-year-old woman presenting with a long history of joint instability, chronic musculoskeletal pain, and iatrogenic bladder and anorectal dysfunction due to irreversible nerve damage after surgical excision of a meningeal cyst. Her clinical characteristics are compared with those of previously reported patients, as well as two further cases originally diagnosed with Hajdu-Cheney and Ehlers-Danlos syndromes, but displaying typical features of LMS.

Longitudinal hormonal evaluation in a patient with disorder of sexual development, 46,XY karyotype and one NR5A1 mutation.

Steroidogenic factor 1 (encoded by the NR5A1 gene) is a critical regulator of reproduction, controlling transcription of key genes involved in sexual dimorphism. To date, NR5A1 variants have been found in individuals with a 46,XY karyotype and gonadal dysgenesis, as well as with a wide spectrum of genital anomalies and, in some patients, with adrenal insufficiency. We describe evolution of gonadal function, from the neonatal period to puberty, in a patient with a 46,XY karyotype, a disorder of sexual development, and a mutation (c.691_699dupCTGCAGCTG) in the NR5A1 gene. The patient, ascertained at birth due to ambiguous genitalia, showed normal values of plasma testosterone in the late neonatal period. Evaluation of the hormonal profile over time indicated severe tubular testicular hypofunction suggestive for a 46,XY disorder of gonadal development. A comprehensive review of published reports of 46,XY and disordered sexual development related to the NR5A1 gene confirmed the clinical and hormonal variability in patients with NR5A1 mutations. Analysis of multiple data allowed us to define the most common features associated with NR5A1 mutations. We further confirmed the indication to perform NR5A1 screening in patients with 46,XY karyotype and disordered sexual development even when Müllerian structures appear to be absent and plasma testosterone levels are within the normal range for age.

Molecular characterization of 11 Italian patients with Darier disease.

Darier disease (DD) is an autosomal dominant genodermatosis characterized by multiple warty papules coalescing in seborrheic areas and specific histological skin changes. Heterozygous mutations in ATP2A2, encoding the sarco-endoplasmic reticulum calcium pumping ATPase type 2, are identified as the molecular basis of DD. In this study, molecular features in a large cohort of Italian patients are reported. Molecular data were collected along with the main clinical features. Genomic DNA was used for direct sequencing of ATP2A2. The effect of selected mutations was predicted by in silico analysis or investigated by gene expression studies. 10 different ATP2A2 mutations were identified. Three mutations (c.2300A>G, c.2794G>A, c.569delAins34) have been previously described, while 7, including 2 missense (c.545G>A and c.2116G>A), 2 nonsense (c.1372G>T and c.1675C>T), 1 small deletion (c.142delA), 1 duplication (c.2935_2949dup15) and 1 splice-site mutation (c.2742-1G>A), were novel. Collected data added new variants to the ATP2A2 repertoire and confirmed that ATP2A2 mutations are scattered over the entire gene and, in most cases, private.

A novel missense mutation in SLC40A1 results in resistance to hepcidin and confirms the existence of two ferroportin-associated iron overload diseases.

Ferroportin-related iron overload disease differs from haemochromatosis in that it has a dominant mode of inheritance and is usually associated with macrophage iron sequestration. However, it is thought that mutations with opposite effects on protein functions, i.e. loss-of-function versus gain-of-function mutations, are responsible for variable phenotype presentations. The present study investigated the functional relevance of a novel ferroportin variant: the c.1502 A>G transition, which changes amino acid 501 from tyrosine to cysteine (p.Y501C). This novel variant was identified in a pedigree originating from Central Italy and, although an intra-familial phenotype heterogeneity was observed, it co-segregated with an iron overload picture similar to that of the HFE-related typical haemochromatosis. In cultured cells, the p.Y501C mutant protein reached the plasma membrane and retained a full iron export ability. By contrast, it was resistant to inhibition by hepcidin. These findings confirm that certain ferroportin mutations compromise the activity of hepcidin in iron homeostasis, mimicking hepcidin deficiency as described in all types of hemochromatosis.

Association of hepcidin promoter c.-582 A>G variant and iron overload in thalassemia major.

Hepcidin is a 25-amino acid peptide, derived from cleavage of an 84 amino acid pro-peptide produced predominantly by hepatocytes. This molecule, encoded by the hepcidin antimicrobial peptide (HAMP) gene shows structural and functional properties consistent with a role in innate immunity. Moreover, as demonstrated in mice and humans, hepcidin is a major regulator of iron metabolism, and acts by binding to ferroportin and controlling its concentration and trafficking. In this study we investigated the influence that mutations in HAMP and/or hemocromatosis (HFE) genes might exert on iron metabolism in a group of poly-transfused thalassemic patients in preparation for bone marrow transplantation. Our results showed that the presence of the c.-582 A>G polymorphism (rs10421768) placed in HAMP promoter (HAMP-P) might play a role in iron metabolism, perhaps varying the transcriptional activation that occurs through E-boxes located within the promoter.

Darier disease, multiple bone cysts, and aniridia due to double de novo heterozygous mutations in ATP2A2 and PAX6.

Darier disease (DD) is an autosomal dominant genodermatosis caused by mutations in ATP2A2 and characterized by multiple warty papules coalescing in seborrheic areas and specific histological skin changes. Rare patients are described with variable bone involvement, but this association has never been sufficiently emphasized. Aniridia is a developmental disorder of the eye due to heterozygous mutations in PAX6. DD and aniridia are Mendelian traits mapping on independent loci and have never been reported in association. Here, we describe a 14-year-old girl showing the unique combination of DD, multiple bone cysts, and bilateral aniridia. Molecular investigations demonstrated that such a complex phenotype is due to double de novo heterozygous mutations in ATP2A2 and PAX6. Review of the literature indicates that, in DD, bone cysts are true developmental abnormalities of the skeleton. This finding suggests a role for ATP2A2 in bone biology. More systematic studies are expected in order to estimate the true prevalence of bone cysts in DD and the relationship between skeletal changes and ATP2A2 perturbation.

Syndromic true hermaphroditism due to an R-spondin1 (RSPO1) homozygous mutation.

XX true hermaphroditism, also know as ovotesticular disorder of sexual development (DSD), is a disorder of gonadal development characterized by the presence of both ovarian and testicular tissue in a 46,XX individual. The genetic basis for XX true hermaphroditism and sex reversal syndromes unrelated to SRY translocation is still mostly unclear. We report mutational analysis of the RSPO1 gene in a 46,XX woman with true hermaphroditism, palmoplantar keratoderma, congenital bilateral corneal opacities, onychodystrophy, and hearing impairment. R-spondin1 is a member of the R-spondin protein family and its pivotal role in sex determination has been recently described. We identified a homozygous splice-donor-site mutation in the RSPO1 gene in our patient. We found that the c.286+1G>A mutation led to an aberrantly spliced mRNA (r.95_286del), which is presumably translated into a partially functional protein (p.Ile32_Ile95del). Our case demonstrates for the first time, to our knowledge, that XX true hermaphroditism can be caused by a single gene mutation. The reported findings represent a further step toward a complete understanding of the complex mechanisms leading to DSDs.

Identification of a novel duplication in the APC gene using multiple ligation probe amplification in a patient with familial adenomatous polyposis.

Germline mutations in the adenomatous polyposis coli (APC) gene cause familial adenomatous polyposis (FAP), an autosomal dominant disease characterized by hundreds to thousands of adenomatous polyps in the colon and rectum, with progression to colorectal cancer. The majority of APC mutations are nucleotide substitutions and frameshift mutations that result in truncated proteins. Recently, large genomic alterations of the APC gene have been reported in FAP. DNA from 15 FAP patients, in whom no APC germline mutations were detected with denaturing high performance liquid chromatography, was analyzed with multiplex ligation-dependent probe amplification (MLPA) to evaluate gross genomic alterations in the APC gene. In one case, MLPA identified a novel duplication of exons 2-6 in one copy of the APC gene. Reverse transcriptase-polymerase chain reaction revealed that the mutant allele contained an in-frame multiexon duplication including 18 nucleotides located in exon 2, upstream of the ATG initiation codon. The presence of a premature stop codon in the duplicated sequence leads to the synthesis of a truncated APC polypeptide. These findings highlight the utility of evaluating infrequent APC mutation events in FAP patients using MLPA.

Prediction and visualization data for the interpretation of sarcomeric and non-sarcomeric DNA variants found in patients with hypertrophic cardiomyopathy.

Genomic technologies are redefining the understanding of genotype-phenotype relationships and over the past decade, many bioinformatics algorithms have been developed to predict functional consequences of single nucleotide variants. This article presents the data from a comprehensive computational workflow adopted to assess the biomedical impact of the DNA variants resulting from the experimental study "Molecular analysis of sarcomeric and non-sarcomeric genes in patients with hypertrophic cardiomyopathy" (Bottillo et al., 2016) [1]. Several different independently methods were employed to predict the functional consequences of alleles that result in amino acid substitutions, to study the effect of some DNA variants over the splicing process and to investigate the impact of a sequence variant with respect to the evolutionary conservation.

Molecular analysis of sarcomeric and non-sarcomeric genes in patients with hypertrophic cardiomyopathy.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is a common genetic heart disorder characterized by unexplained left ventricle hypertrophy associated with non-dilated ventricular chambers. Several genes encoding heart sarcomeric proteins have been associated to HCM, but a small proportion of HCM patients harbor alterations in other non-sarcomeric loci. The variable expression of HCM seems influenced by genetic modifier factors and new sequencing technologies are redefining the understanding of genotype-phenotype relationships, even if the interpretations of the numerous identified variants pose several challenges. METHODS AND RESULTS: We investigated 62 sarcomeric and non-sarcomeric genes in 41 HCM cases and in 3 HCM-related disorders patients. We employed an integrated approach that combines multiple tools for the prediction, annotation and visualization of functional variants. Genotype-phenotype correlations were carried out for inspecting the involvement of each gene in age onset and clinical variability of HCM. The 80% of the non-syndromic patients showed at least one rare non-synonymous variant (nsSNV) and among them, 58% carried alterations in sarcomeric loci, 14% in desmosomal and 7% in other non-sarcomeric ones without any sarcomere change. Statistical analyses revealed an inverse correlation between the number of nsSNVs and age at onset, and a relationship between the clinical variability and number and type of variants. CONCLUSIONS: Our results extend the mutational spectrum of HCM and contribute in defining the molecular pathogenesis and inheritance pattern(s) of this condition. Besides, we delineate a specific procedure for the identification of the most likely pathogenetic variants for a next generation sequencing approach embodied in a clinical context.

A novel LAMP2 mutation associated with severe cardiac hypertrophy and microvascular remodeling in a female with Danon disease: a case report and literature review.

BACKGROUND: Danon disease (DD) is a rare disorder characterized by cardiomyopathy, intellectual disability, and proximal myopathy. It is caused by mutations in the LAMP2 gene on X chromosome. Female patients most often present with late-onset cardiomyopathy and slow disease progression, but early-onset cases with unfavorable prognosis have been reported. CASE REPORT: We describe the clinical, pathological, and molecular features of a novel LAMP2 c.453delT mutation in a female patient with severe hypertrophic cardiomyopathy, Wolff Parkinson White (WPW) syndrome and rapid progression to heart failure, requiring heart transplant. Immunohistochemical analysis of LAMP2 in the explanted heart revealed a mosaic pattern of distribution, with discrete clusters of either stained or unstained cardiac myocytes, the latter being more frequent in the septum. These findings paralleled X chromosome inactivation within the myocardium. Interestingly, multiple foci of microscarring were found on histology in the Left Ventricle (LV) free wall and septum, in a close spatial relationship with remodeling and severe stenosis of intramural coronary arterioles. CONCLUSIONS: Our findings suggest that several features may contribute to the early and severe cardiac phenotype in female DD patients. The type of mutation may account for the early disease onset, while both the inhomogeneous distribution of LAMP2 loss and the presence of microvascular remodeling may be determinant in the rapid progression to heart failure.

Disorders of sex development: a genetic study of patients in a multidisciplinary clinic.

Sex development is a process under genetic control directing both the bi-potential gonads to become either a testis or an ovary, and the consequent differentiation of internal ducts and external genitalia. This complex series of events can be altered by a large number of genetic and non-genetic factors. Disorders of sex development (DSD) are all the medical conditions characterized by an atypical chromosomal, gonadal, or phenotypical sex. Incomplete knowledge of the genetic mechanisms involved in sex development results in a low probability of determining the molecular definition of the genetic defect in many of the patients. In this study, we describe the clinical, cytogenetic, and molecular study of 88 cases with DSD, including 29 patients with 46,XY and disorders in androgen synthesis or action, 18 with 46,XX and disorders in androgen excess, 17 with 46,XY and disorders of gonadal (testicular) development, 11 classified as 46,XX other, eight with 46,XX and disorders of gonadal (ovarian) development, and five with sex chromosome anomalies. In total, we found a genetic variant in 56 out of 88 of them, leading to the clinical classification of every patient, and we outline the different steps required for a coherent genetic testing approach. In conclusion, our results highlight the fact that each category of DSD is related to a large number of different DNA alterations, thus requiring multiple genetic studies to achieve a precise etiological diagnosis for each patient.