Novel and recurrent p14 mutations in Italian familial melanoma.

CDKN2A and CDK4 are the only known high-penetrant genes conferring proneness to cutaneous melanoma. The CDKN2A locus consists of four exons and encodes several alternate transcripts, two of which are p16(INK4a) and p14(ARF), and originate from different open reading frames. Exon 1alpha is specific for p16(INK4a), while exon 1beta characterizes p14(ARF). Most CDKN2A mutations are located in exons 1alpha and 2, while exon 1beta variations have been identified in rare melanoma-prone pedigrees. In a previous study, we investigated 155 Italian melanoma cases, including 94 familial melanomas (FAMs) and 61 sporadic multiple primary melanomas (MPMs), for p16(INK4a)/CDK4 germline alterations and identified 15 p16(INK4a) and 1 CDK4 point mutations. In the present work, we extended our search to p14(ARF) mutations and CDKN2A deletions in the remaining samples. We identified the recurrent g.193+1G> A mutation in two FAM cases, while an additional pedigree displayed the previously undescribed variant g.161G> A. Multiplex ligation-dependent probe amplification (MLPA) screening for copy variations resulted negative in all cases. In Italy, the overall frequency of p14(ARF) mutations is 3.2% in FAM and 0% in sporadic MPM. Re-evaluation of our patients' cohort emphasizes that the chance of identifying CDKN2A/CDK4 mutations in FAM is mainly influenced by the number of affected family members and the presence of one or more MPM cases. Accordingly, mutation rate rises to 61% in selected cases. Further studies are expected in order to investigate CDKN2A rarer mutations, including atypical deletions and inherited epimutations.

Complex multipathways alterations and oxidative stress are associated with Hailey-Hailey disease.

BACKGROUND: Hailey-Hailey disease (HHD) is an autosomal dominant disorder characterized by suprabasal cutaneous cell separation (acantholysis) leading to the development of erosive and oozing skin lesions. While a strong relationship exists between mutations in the gene that encodes the Ca(2+)/Mn(2+)-adenosine triphosphatase ATP2C1 and HHD, we still have little understanding of how these mutations affect manifestations of the disease. OBJECTIVES: This study was designed to determine early signalling events that affect epithelial cell growth and differentiation during HHD development. METHODS: Expression of key regulatory signals important for maintaining skin homeostasis were evaluated by Western blot analysis and by reverse transcriptase-polymerase chain reaction in primary keratinocytes obtained from skin biopsies of patients with HHD. Reactive oxygen species accumulation in primary keratinocytes derived from lesional skin of patients with HHD was assessed by dihydrorhodamine 123 (DHR) assay. RESULTS: HHD-derived keratinocytes showed downregulation of both Notch1 and differential regulation of different p63 isoforms. Itch and p63 are co-expressed in the epidermis and in primary keratinocytes where Itch controls the p63 protein steady-state level. We found that the Itch protein was significantly decreased in HHD-derived keratinocytes whereas the expression of its target, c-Jun, remained unaffected. We also found that HHD-derived keratinocytes undergo oxidative stress, which may explain both Notch1 and Itch downregulation. CONCLUSIONS: Our attempt to explore the molecular mechanism underlying HHD indicates a complex puzzle in which multi-hit combinations of altered signal pathways may explain the wide spectrum of defects in HHD.

Homozygous p.M172K mutation of the TFR2 gene in an Italian family with type 3 hereditary hemochromatosis and early onset iron overload.

The p.M172K TFR2 mutation was identified in two Italian siblings aged 32 and 40 years old with primary iron overload. The two patients showed a severe increase in serum iron indices. From the age of 25, the male sib also revealed abnormal levels of hepatic enzymes, presumably in relation to iron induced liver damage. Clinical findings seem to evidence that type 3 hemochromatosis can be more serious than classic hemochromatosis. This report adds two more type 3 hereditary hemochromatosis cases which suggest that TFR2 mutations could be more frequently involved in non-HFE hemochromatosis than has been actually thought.

Clinical management and molecular cytogenetic characterization in a 45,X/46,X,idic(Yp) patient with severe hypospadia.

Cryptorchidism and proximal hypospadia in a newborn are highly suspicious for an intersex disorder, and proper investigations should be planned immediately after birth. In some hypospadic patients, the presence of a palpable gonad in the scrotum may induce to assign the male sex, whereas the anatomy of internal and external genitalia could be extremely complex, requiring an accurate evaluation before any definitive attribution of gender. The authors present a case of an infant, referred to the hospital for surgical treatment of a proximal hypospadia, who showed ambiguous external genitalia, absence of the right gonad, a partially dysgenetic left testis, and presence of both müllerian and wolffian structures. Cytogenetic analysis detected a mosaicism with a cell line showing an isodicentric Yp chromosome and a second one, a 45, X chromosomal complement. Because the baby had been assigned previously to male gender, he underwent a staged masculinizing correction of the genital anomalies. The authors discuss the necessity of a careful evaluation of these patients at birth by a multispecialistic team, for appropriate sex assignment and for the assessment of the risk of neoplastic degeneration.

Cytogenetic and molecular characterization of a de novo 4q24qter duplication and correlation to the associated phenotype.

We report on a newborn with severe psychomotor retardation, minor anomalies, congenital heart defects, thumb and urogenital abnormalities. Cytogenetic analysis showed a 4q24qter duplication, never described before, as the result of a de novo t(4;14). The extension of the duplicated 4q region was defined by FISH using YAC probes. The breakpoint was localized between 106.3cM (YAC 800f2, D4S1572) and 111 cM (YAC 744e4, D4S1564). Comparing our patient with those previously reported in literature, we observed some features mature frequently reported in these patients: psychomotor retardation, retromicrognathia, low set and/or malformed ears and some more specific traits: congenital cardiac defects, hypoplastic thumb and urogenital abnormalities.

CDKN2A novel mutation in a patient from a melanoma-prone family.

CDKN2A is thought to be the main candidate gene for melanoma susceptibility. Deletion or mutations in the CDKN2A gene may produce an imbalance between functional p16 and cyclin D, causing abnormal cell growth. We here describe a novel mutation consisting of a 1 bp deletion at nucleotide position 201 (codon 67) (CACGGcGCG) resulting in a truncated protein (stop codon 145). The patient, a female subject from a melanoma-prone family, presented at the age of 47 years with a superficial spreading melanoma of the trunk. Her father had colon cancer at the age of 43 years and melanoma at 63 years, her uncle suffered from gastric cancer, and her grandfather had laryngeal cancer.

Identification of novel RP2 mutations in a subset of X-linked retinitis pigmentosa families and prediction of new domains.

X-linked Retinitis Pigmentosa (XLRP) shows a huge genetic heterogeneity with almost five distinct loci on the X chromosome. So far, only two XLRP genes have been identified, RPGR (or RP3) and RP2, being mutated in approximately 70% and 10% of the XLRP patients. Clinically there is no clearly significative difference between RP3 and RP2 phenotypes. In the attempt to assess the degree of involvement of the RP2 gene, we performed a complete mutation analysis in a cohort of patients and we identified five novel mutations in five different XLRP families. These mutations include three missense mutations, a splice site mutation, and a single base insertion, which, because of frameshift, anticipates a stop codon. Four mutations fall in RP2 exon 2 and one in exon 3. Evidence that such mutations are different from the 21 RP2 mutations described thus far suggests that a high mutation rate occurs at the RP2 locus, and that most mutations arise independently, without a founder effect. Our mutation analysis confirms the percentage of RP2 mutations detected so far in populations of different ethnic origin. In addition to novel mutations, we report here that a deeper sequence analysis of the RP2 product predicts, in addition to cofactor C homology domain, further putative functional domains, and that some novel mutations identify RP2 amino acid residues which are evolutionary conserved, hence possibly crucial to the RP2 function.

Dot-and-fleck retinopathy in Alport syndrome caused by a novel mutation in the COL4A5 gene.

PURPOSE: To describe an unusual form of dot-and-fleck retinopathy in a slower progressive form of X-linked Alport syndrome, caused by a novel missense mutation in the COL4A5 gene. METHOD: Ophthalmic examination, polymerase chain reaction, and single-strand conformational polymorphism analysis of genomic DNA were performed in the proband. RESULTS: Ophthalmoscopy revealed classic dot-and-fleck retinopathy but located in an unusual site. A novel COL4A5 gene mutation changing glycine to cysteine at 177 was identified. CONCLUSIONS: Although there is no correlation between mutation site and the resulting phenotype in Alport syndrome, our findings suggest that further novel mutations and different ocular manifestations may be associated with Alport syndrome.

Mutation analysis of the RPGR gene reveals novel mutations in south European patients with X-linked retinitis pigmentosa.

The RPGR (retinitis pigmentosa GTPase regulator) gene has been shown to be mutated in 10-20% of patients with X-linked retinitis pigmentosa (XLRP), a severe form of inherited progressive retinal degeneration. A total of 29 different RPGR mutations have been identified in northern European and United States patients. We have performed mutation analysis of the RPGR gene in a cohort of 49 southern European males affected with XLRP. By multiplex SSCA and automatic direct sequencing of all 19 RPGR exons, seven different and novel mutations were identified in eight of the 49 families; these include three splice site mutations, two microdeletions, and two missense mutations. RNA analysis showed that the three splice site defects resulted in the generation of aberrant RPGR transcripts. Six of these mutations were detected in the conserved amino-terminal region of RPGR protein, containing tandem repeats homologous to the RCC1 protein, a guanine nucleotide-exchange factor for Ran-GTPase. Several exonic and intronic sequence variations were also detected. None of the RPGR mutations reported in other populations were identified in our series. Our results are consistent with the notions of heterogeneity and minority causation of XLRP by mutations in RPGR in Caucasian populations.

Detection of a 46,XX,der(3)t(3;4)(p25;p16.1) by using chromosome microdissection.

We performed chromosome microdissection in order to define the "de novo" rearrangement observed in a female patient affected by: frontal microgyria, mild psychomotor retardation, thoracic scoliosis, XIIth rib asymmetry and facial dysmorphisms. Through the use of the micro-FISH we evidenced a deletion of the 3p25pter region and a 4p16.1 duplication. We performed a karyotype-phenotype correlation in our patient and in the ones previously reported in literature which had a 3p25pter deletion or the 4p16 duplication.