A novel LITAF/SIMPLE mutation within a family with a demyelinating form of Charcot-Marie-Tooth disease.

Charcot-Marie-Tooth disease type 1 (CMT1) is a common disorder of the peripheral nervous system. The underlying genetic cause is highly heterogeneous, and mutations in SIMPLE (small integral membrane protein of lysosome/late endosome) represent a rare cause of CMT type 1, named CMT1C. Herein, we report the clinical, electrophysiological, and neuropathological findings of an Italian CMT1 family with a novel SIMPLE missense mutation. The family exhibited electrophysiological signs of demyelination, predominantly affecting the lower limbs, with conduction blocks, and a wide variability of age of onset among the members. Molecular analysis identified the novel heterozygous missense mutation p.Pro135Arg in SIMPLE which co-segregated with the disease within the pedigree. In conclusion, our findings confirm that the genetic analysis of LITAF/SIMPLE should be considered for the diagnostic flow-chart of CMT1 patient, especially when nerve conduction studies show the presence of conduction blocks.

HSPB1 and HSPB8 in inherited neuropathies: study of an Italian cohort of dHMN and CMT2 patients.

Mutations in the small heat-shock protein 27 kDa protein 1 (HSPB1) and 22 kDa protein 8 (HSPB8) genes were associated with distal hereditary motor neuropathy (dHMN) and with the axonal form of Charcot-Marie-Tooth disease type 2 (CMT2). Here we report the clinical and molecular evaluation of an Italian dHMN and CMT2 cohort to establish HSPB1 and HSPB8 mutation occurrence and associated clinical features. One hundred and sixty-seven patients with dHMN or CMT2 were studied. HSPB1 and HSPB8 exons 1 and 3 molecular analysis was carried out through DHPLC and direct sequencing of each variant chromatogram. HSPB8 exon 2 was analyzed by direct sequencing. Four mutations in five unrelated dHMN patients and four mutations in four unrelated CMT2 cases were found in HSPB1. The p.Arg136Leu mutation was found in two patients with different phenotypes. Electroneurographical follow-up study in a dHMN patient revealed that sensory impairment occurred with disease progression. The HSPB1 mutation frequency was 8% in dHMN and 4% in CMT2 patients. The significant HSPB1 mutation frequency in both phenotypes indicates its relevance in the pathogenesis of these neuropathies. Recent literature data suggest a continuum between dHMN and CMT2. We confirm this finding in our cohort, proposing a definite relationship between these disorders.

Currarino syndrome with pelvic neuroendocrine tumor diagnosed by post-mortem genetic analysis of tissue specimens.

Currarino syndrome (CS) is an autosomal dominant disorder of embryonic development characterized by the triad of anorectal abnormalities, partial sacral agenesis, and presacral mass. Mutations of the HLXB9 gene have been identified in most CS cases, but a precise genotype-phenotype correlation has not been described so far. We report the clinical case of a 44-year-old Caucasian woman with malignant neuroendocrine transformation of a pre-sacrococcygeal mass combined with bicornuate uterus, dermoid cyst of the ovaries, and chronic constipation. After the patient died, a sacrococcygeal malformation and anterior meningocele were diagnosed in her 22-year-old son. CS diagnosis was then retrospectively confirmed by molecular analysis of normal and pathological tissue specimens of the mother, with identification of a HLXB9 mutation (c.727C>T; p.R243W). CS should be considered, and genetic counseling recommended, to all patients with presacral masses. Since malignant neuroendocrine transformation of presacral mass in CS is a possible complication, even thought rare, close follow up in these patients is advisable.

Severe neuropathy after diphtheria-tetanus-pertussis vaccination in a child carrying a novel frame-shift mutation in the small heat-shock protein 27 gene.

Mutations in small heat-shock protein 27 and small heat-shock protein 22 genes were found in association with Charcot-Marie-Tooth disease type 2 and distal hereditary motor neuropathy. We searched for mutations in small heat-shock protein 27 gene in an Italian family with peripheral neuropathy and intrafamilial phenotypic variability. A novel heterozygous frame-shift mutation c.476_477delCT was found while point mutations in most genes associated with hereditary neuropathies were ruled out. In the proband, who showed a severe early onset peripheral neuropathy, an independent pathogenetic effect on the peripheral nervous system secondary to the tetanus toxoid injection may be supposed. This is the first truncating nonsense mutation in the small heat-shock protein 27 gene identified so far and the clinical, neurophysiologic, and neuropathological findings are discussed.

Germline mutations in the von Hippel-Lindau gene in Italian patients.

von Hippel-Lindau syndrome (VHL) is a dominantly inherited familial cancer syndrome predisposing to a variety of malignant and benign tumours, most frequently retinal, cerebellar, and spinal hemangioblastoma, renal cell carcinoma, pheochromocytoma, and pancreatic tumours. The current study investigated the occurrence of VHL mutations in Italian patients with classic VHL disease or with atypical VHL-like clinical features referred to the Service of Medical Genetics for VHL molecular diagnosis. In addition, an RQ-PCR protocol was validated in order to introduce it in the routine VHL laboratory diagnosis.

Reliability and reproducibility of a RNA preamplification method for low-density array analysis from formalin-fixed paraffin-embedded breast cancer samples.

Molecular signatures of tumors with prognostic and predictive value are now available. However, several technical problems prevent the performing of gene expression profiles in routine diagnostics. The highly sensitive fluorescence-based real-time quantitative reverse transcriptase-polymerase chain reaction procedure is able to analyze mRNA levels from formalin-fixed paraffin-embedded (FFPE) tissues, the most commonly available source of tumor samples with well-documented information. However, the time-dependent fragmentation and small amount of RNA extracted from FFPE requires a preliminary mRNA amplification step to amplify small amounts of mRNA without significantly distorting relative mRNA levels. The purpose of this study was to determine the performance of a commercial cDNA preamplification kit (TaqMan PreAmp Master Mix Kit) on RNA samples obtained from FFPE tissues, prepared, and archived for routine diagnosis. We tested the reliability and reproducibility of this procedure for performing low-density gene expression assay from FFPE tissue samples. The whole procedure reported herein is a powerful and reproducible approach for routine clinical purposes that can be performed even using poorer RNA quality samples and that allows the analysis of gene expression for 96 genes in stored samples.

Clinical features and molecular modelling of novel MPZ mutations in demyelinating and axonal neuropathies.

Mutations in the myelin protein zero (MPZ) gene have been associated with different Charcot-Marie-Tooth disease (CMT) phenotypes, including classical demyelinating CMT1B and the axonal form of the disease (CMT2). The MPZ role in the pathogenesis of both demyelinating and axonal inherited neuropathies was evaluated in the Italian population by screening a cohort of 214 patients with CMT1 or CMT2. A MPZ mutation frequency of 7.9% in demyelinating cases and of 4.8% in axonal cases was observed. In the total cohort (264 patients), including those with mutations in other genes, a mutation frequency of 5.8% (7/121) in demyelinating cases and 4.2% (6/143) in axonal cases was found. Three novel MPZ mutations, two missense (p.Ser111Cys, p.Thr124Ala) and one frameshift (p.Tyr145fs) were found, and a molecular modelling approach was used to test the effects of these mutations on the protein structure. Electrostatic distribution changes within the protein, caused by the amino acid substitution, fit in with phenotypes presented by patients herein described. Our findings suggest that the clinical features associated with MPZ mutations depend partly on the nature of amino acid change and that molecular modelling may provide useful support, based on effects on secondary and tertiary protein structure, to predict the phenotype associated with MPZ mutations.

Gap junction beta 1 (GJB1) gene mutations in Italian patients with X-linked Charcot-Marie-Tooth disease.

X-linked Charcot-Marie-Tooth disease (CMT1X) is a peripheral neuropathy transmitted in a dominant manner and caused by mutations in the Connexin 32 (Cx32) gene (GJB1, gap junction beta 1). Here we report the mutation analysis of the GJB1 gene in 76 subjects with possible CMT1 and absence of 17p11.2 duplication, and in 38 CMT2 patients without mutations in CMT2-associated-genes, selected from a cohort of 684 patients with peripheral sensory-motor neuropathy. The analysis was performed by direct sequencing of the coding sequence and exon/intron boundaries of the GJB1 gene. The mutation screening identified 22 mutations in GJB1, eight of which have not been previously published: six point mutations (c.50C > G, c.107T > A, c.545C > T, c.545C > G, c.548G > C, c.791G > T) and two deletions (c.84delC, c.573_581delCGTCTTCAT). The GJB1 mutation frequency (19.3%) and the clinical heterogeneity of our patients suggest searching for GJB1 mutations in all CMT cases without the 17p11.2 duplication, regardless of the gender of the proband, as well as in CMT2 patients with possible X-linked inheritance.

No evidence of association between BDNF gene variants and age-at-onset of Huntington's disease.

Huntington's disease (HD) is a late-onset, autosomal dominant neurodegenerative disease caused by a CAG trinucleotide expansion. The number of repeats on the HD chromosome explains most of the variability in age of onset, but genetic factors other than the HD gene are responsible for part of the residual variance. Based on the role played by the brain derived neurotrophic factor (BDNF) in neurodysfunction and neurodegeneration in HD, we searched for novel polymorphisms in the neuron restrictive silencer element located in the BDNF promoter. Then, the effect of the Val66Met variant in determining age of onset was tested in a large sample of HD carriers by using a multivariate regression approach. The CAG repeat number accounted for 62% of the variance. After correction for the predominant effect of the CAG expansion, no multiple regression model provided evidence of association between the Val66Met genotype and variation in age-at-onset. Additional studies are warranted to further investigate BDNF as genetic modifier of the HD phenotype.

Multifocal bilateral renal cell carcinoma and retinal angiomas in a patient with de novo von Hippel-Lindau disease: identification of a new germline mutation.

Von Hippel-Lindau (VHL) disease is a rare autosomal dominant disorder characterized by multifocal and bilateral renal cell carcinoma and cysts, retinal angiomas, hemangioblastoma of the central nervous system, pheochromocytoma, epididymis cystoadenoma, pancreatic cysts and/or islet cell tumors. However, phenotypic manifestations and clinical outcome are wide ranging including inter and intra-familial patterns. The VHL gene has been localized on chromosome 3 p 25-26 and more than 250 germline mutations have been described. The sensitivity of analytic techniques of VHL gene is close to 100%. It is well known that about 25% of VHL patients present de novo mutations, and first cases function as possible founders of new VHL kindreds. Herein, we report the clinical case of a 45-year-old Caucasian female patient affected by bilateral polycystic kidney disease with two renal carcinomas in both kidneys without lynphoadenopathies. She underwent ophthalmologic surgery at 19 years old because of retinal detachment due to bilateral retinal angiomatosis. Direct gene sequencing showed a deletion-insertion in exon 3, starting from nucleotide 499 of the coding sequence (c.499-504 delinstT) in a heterozygous status; it causes a frame-shift and creates a premature stop at codon 170. The genetic study of the unaffected parents and of the unaffected brother confirmed the diagnosis of de novo VHL disease with the dentification of a new germline mutation, never reported in the literature. The patient showed normal kidney function and she did not show other organ lesions or clinical manifestations of VHL disease. She was successfully submitted to renal parenchymal sparing-surgery. In conclusion, it is important to test for germline mutations in VHL patients with the involvement of one organ or a pair of organs. Once the mutation is found in the proband, all family members can be easily tested for the documented mutation. The early identification of VHL patients is very important for clinical and genetic reasons.

Early onset may predict G101W CDKN2A founder mutation carrier status in Ligurian melanoma patients.

Although the presence of multiple cases of melanoma on the same side of a family is the best predictor of germline CDKN2A mutation, other features (i.e. early age at onset) may be useful to identify carriers. We analysed the records of 682 hospital-based Ligurian melanoma patients. Of these, 238 cases (34 familial, 14 non-familial multiple primary and 190 non-familial single primary melanomas) were consecutively enrolled for screening of the CDKN2A and CDK4 genes. Screening of the 34 familial patients revealed that nine were carriers of the CDKN2A G101W founder mutation. Of the 14 non-familial multiple primary melanoma patients, three carried the G101W founder mutation and one the P48T mutation. For the non-familial patients with a single melanoma, 17 of 190 carried germline CDKN2A mutations, with most (16/17) carrying the G101W Ligurian founder mutation and one a novel single base pair substitution, D74Y. The effect of mutation on age at diagnosis was significant (P=0.012) after correcting for melanoma type (familial or non-familial), number of primaries (single or multiple), gender and disease occurrence (incident or prevalent). Early age at onset may be a good predictor of CDKN2A mutation in Liguria, where the G101W founder mutation is prevalent among melanoma patients, independent of family history.

Triplet repeat primed PCR (TP PCR) in molecular diagnostic testing for Friedreich ataxia.

Friedreich ataxia (FRDA), an autosomal recessive neurodegenerative disease, is associated with an unstable expansion of a GAA trinucleotide repeat in the first intron of the frataxin gene on chromosome 9q13. Unequivocal molecular characterization of the FRDA triplet expansion requires the use of different PCR protocols to amplify normal and mutated alleles combined with Southern blotting analysis to accurately size the expansion. Nevertheless, expansion detection by PCR may be somewhat problematic in heterozygous individuals. The purpose of this study was to evaluate triplet repeat primed PCR (TP PCR) as a screening method for FRDA diagnosis in the diagnostic laboratory. Fifty-four cases referred either to confirm the diagnosis of FRDA or to detect carrier status were re-evaluated by the TP PCR method. The TP PCR assay correctly identified the FRDA status in all 54 individuals tested including homozygous expansions (9 individuals), heterozygous expansions (20 individuals), and non-carriers (25 individuals). Results showed 100% concordance with those obtained by Southern blot analysis. TP PCR allowed us to identify the expanded alleles or to demonstrate their absence in DNA samples where conventional PCR procedures failed to give a reliable result. TP PCR represents an additional valuable tool for mutation detection in FRDA patients and carriers, but also can be used as screening test in a diagnostic laboratory.

Does parkin play a role in the peripheral nervous system? A family report.

Two genes were identified for autosomal recessive forms of early onset Parkinson's disease: parkin and DJ-1. We describe 2 siblings with EOPD due to parkin mutations and peripheral neuropathy, which presented as neuropathy with liability to pressure palsies (HNPP) in the index case. RT-PCR experiments revealed that the parkin gene is expressed in sural nerves from both controls and patient with parkin-related disease. Our findings support the view that parkin may play a role in the peripheral nervous system.

Juvenile renal cell carcinoma as first manifestation of von Hippel-Lindau disease.

Von Hippel-Lindau (VHL) disease is an autosomal dominant syndrome characterized by germline mutations in the VHL tumor suppressor gene located at chromosome 3p25-26 and pleomorphic clinical picture. The major clinical manifestations include retinal angiomas, central nervous system hemangioblastomas, pheopleochromocytoma, pancreatic cysts, epididymal cystoadenomas and renal lesions. Recently, we observed a 58-year-old male patient with macrohematuria and a history of nephrectomy due to renal cell carcinoma (RCC). The patient showed retinal angiomatosis, cerebellar hemangioblastomas, multiple pancreatic cysts, right kidney with polycystic features plus two RCC. The patient's offspring, two females and one male, showed VHL lesions, such as retinal angiomatosis, cerebellar hemangioblastomas and polycystic kidney disease (PKD). The affected family members were screened for mutations in the VHL gene. Data suggested the presence of a deletion encompassing exon 1 of the VHL gene. Early diagnosis of VHL disease in patients and their relatives is important for clinical and geneticreasons. VHL disease patients have an increased incidence of malignant carcinomas and the syndrome can mimic the presentation of other cystic kidney diseases. Early diagnosis and molecular genetic testing of family members is essential to improve the clinical management of patients and to allow an accurate risk assessment in asymptomatic individuals. In conclusion, nephrologists and urologists must carefully evaluate patients with PKD and RCC to confirm or exclude VHL disease, and physicians must play a crucial role in the clinical process of therapeutical decisions and choices for VHL patients.

High prevalence of the G101W germline mutation in the CDKN2A (P16(ink4a)) gene in 62 Italian malignant melanoma families.

CDKN2A germline mutation frequency estimates are commonly based on families with several melanoma cases. When we started counseling in a research setting on gene susceptibility analysis in northern and central Italy, however, we mostly found small families with few cases. Here we briefly characterize those kindred, estimate CDKN2A/CDK4 mutation test yields, and provide indications on the possibility of implementing formal DNA testing for melanoma-prone families in Italy. In September 1995 we started genetic counseling in a research setting at our Medical Genetics Center. Screening for CDKN2A/CDK4 mutations was performed on families with two melanoma patients, one of whom was younger than 50 years at onset, the other complying with one of the following: 1) being a first-degree relative, 2) having an additional relative with pancreatic cancer, or 3) having multiple primary melanomas. Sixty-two of 67 (80%) melanoma cases met our criteria. Four previously described CDKN2A mutations (G101W, R24P, V126D, and N71S) were found in 21 of the 62 families (34%) with a high prevalence of G101W (18/21). The percentage of families with two melanoma cases/family harboring a mutation was low (7%, 2/27), but rose to 45% (9/20) if one of the melanoma patients carried multiple melanomas or if pancreatic cancer was present in that family. In the 15 families with three melanoma cases the presence of a mutation was higher (67%, 10/15) and reached 100% in the 4 families with four or more melanoma cases. Our results suggest that CDKN2A/CDK4 counseling-based mutational analysis may be reasonably efficient also for families with two melanoma cases, if one patient carries multiple melanomas or if pancreatic cancer is present in the family.