Fluorescence in situ hybridization (FISH) evaluation of chromosomes 6, 7, 9 and 10 throughout human melanocytic tumorigenesis.

Loss of the 9p21 region, 6q and 10q and gain of chromosome 7 are the most frequent chromosomal abnormalities found in human melanomas, but very few cytogenetic data are available regarding dysplastic and common naevi. To study the occurrence of the most consistent chromosomal changes during melanocytic tumorigenesis, archival samples from 30 common naevi and 30 naevus-associated melanomas were analysed by interphase fluorescence in situ hybridization (FISH) using centromeric probes for chromosomes 9 and 7 and locus-specific probes for 9p21, 6q11.1, 6q24.1, 10p15.3 and 10q23.1 regions. In naevus-associated melanomas, separate evaluations were made for sectors corresponding to residual naevus, dysplastic naevus, radial growth phase melanoma and vertical growth phase melanoma. No chromosomal aberrations were found in common naevi, but monosomy 7 was observed in one case. In naevus-associated melanomas, loss of the entire chromosome 9 or of the 9p21 region was observed in 56% of common and 54% of dysplastic naevus sectors, in 64% of radial growth phase melanoma and in 82% of vertical growth phase melanoma. Loss of the long arm of chromosome 6, monosomy 10 and deletion 10q were exclusively confined to radial (18% for both chromosomes) and vertical (29 and 59%, respectively) growth phase melanomas. Polysomy of chromosome 7 was detected only in melanoma sectors (radial growth phase, 14%; vertical growth phase, 59%). The high incidence of 9p21 loss in melanoma-associated naevi, which is maintained in all evolutionary phases of melanocytic tumorigenesis, and the complete absence of chromosomal aberrations in common naevi, strongly suggest that 9p21 loss may be regarded as a cytogenetic marker of melanocytic naevi with a high potential for progression.

Analysis of SCA8 and SCA12 loci in 134 Italian ataxic patients negative for SCA1-3, 6 and 7 CAG expansions.

Spinocerebellar ataxias (SCA) are a heterogeneous group of neurodegenerative disorders, six of which are caused by expansion of a polyglutamine-coding CAG repeats ( SCA1- 3, 6, 7 and 17). In addition, expansions of a CAG triplet in the 5' region of a gene and a CTG triplet in an antisense RNA have been demonstrated in the SCA12 and SCA8 genes respectively. Our series of 134 ataxic patients (22 familial and 112 sporadic, tested negative for SCAI-3, 6, 7) was investigated for the presence of triplet expansions in the SCA8 and SCA12 genes. No SCA12 expansion was identified. A moderate SCA8 expansion (85-97 repeats) was found in two unrelated families with slowly progressive cerebellar ataxia. The frequency of SCA8 expansion accounts for approximately 4.3 % of the whole pool of our ataxia families (2 out of 46), while none of the 127 controls screened carried > 35 CTG+CTA repeats. Our data suggest a possible pathogenetic role of this mutation, which at present is still controversial, and confirm the rarity of the SCA12 expansion in Italian patients.

Polymorphism of the uteroglobin gene in systemic lupus erythematosus and IgA nephropathy.

Uteroglobin (UG) is a multifunctional protein with anti-inflammatory/immunomodulatory properties. The UG gene is located on the long arm of chromosome 11 (11q12.3-q13.1) in a region linked to some immune disorders. A guanine-adenine substitution at position 38 (A38G) has been found in the noncoding region of exon 1 that is significantly correlated with an increased risk of developing immune-mediated diseases. Recently an experimental model of UG knockout mice showed that in mice, UG deficiency causes severe glomerulopathy with mesangial deposition of IgA-fibronectin complexes. To detect the presence of polymorphisms in the UG coding sequence, the DNA of 109 patients with IgA nephropathy (IgAN), and 32 patients with systemic lupus erythematosus (SLE) were tested for the nucleotide sequence of all three UG exons by heteroduplex analysis. We detected heterozygous DNA only for exon 1 due to the A38G substitution, as confirmed by sequencing. We tested for A38G polymorphism, by restriction endonuclease digestion (Sau96I), both in SLE patients and in IgAN patients. Twenty patients with either membranous nephropathy (12) or focal and segmental glomerular sclerosis and 120 healthy subjects served as controls. Compared with both healthy controls and non-IgA control patients, the frequency of the 38A allele was significantly higher in SLE patients (38 of 64 alleles versus 89 of 240 alleles, p = 0.002, and versus 7 of 40 alleles, p < 0.001). IgAN patients showed an allelic distribution similar to both control groups. A subgroup of 18 IgAN patients undergoing renal replacement therapy because of end-stage renal disease showed a significant increase in 38A allele frequency (5 of 36 38G alleles versus 31 of 36 38A alleles, p < 0.001). UG is an immunomodulatory agent that is able to (a) inhibit the activity of several phospholipase A2 (PLA2s), (b) interfere with the function of both neutrophils and monocytes, and (c) prevent immune recognition, perhaps by masking surface antigens. This could account for the role this molecule plays in SLE. The A38G polymorphism is located within a region corresponding to the rat minimal promoter that proved to be important in the transcriptional regulation of UG. Although the significance of any alterations in the UG exon 1 noncoding region in humans has yet to be clarified, initial evidence suggests that it may alter the control of immune response and of inflammation.