Molecular analysis of the SLC22A12 (URAT1) gene in patients with primary gout.

OBJECTIVE: To analyse the SLC22A12 (URAT1) gene in primary gout patients, first-grade relatives and healthy controls and the possible association of them with demographic and clinical data. SUBJECTS AND METHODS: We included 69 consecutive patients with diagnosis of primary gout, as well as 29 first-grade relatives and 120 healthy volunteers. Demographic and clinical data were obtained from the patients and relatives. DNA was purified from peripheral blood and all 10 exons of the SLC22A12 (URAT1) gene were sequenced. RESULTS: We found six different mutations in the SLC22A12 gene in 16 out of 69 (23%) patients with primary gout. Five mutations were in exon 5 and one in exon 4; five out of six mutations were heterozygous (one compound heterozygous) and one homozygous. The C850G mutation (exon 5) was found in 11 gout patients, these patients have lower levels of triglycerides than the rest of the group: 160 +/- 56 vs 292 +/- 203 mg/dl (P = 0.038). In one family, we found SLC22A12 mutations in three relatives within exon 5. We did not find mutations in the other exons studied (1-3 and 6-10), nor in any of the 10 exons of the 120 healthy volunteers. CONCLUSIONS: We found several mutations in SLC22A12 gene associated with primary gout, the definite role of these mutations in URAT1 activity needs to be further studied.

Carrier identification by FISH analysis in isolated cases of X-linked ichthyosis.

X-linked ichthyosis (XLI) is an inborn error of metabolism due to steroid sulfatase (STS) deficiency. STS assay and FISH are useful in diagnosing carrier status of XLI. Biochemical analysis appears to indicate that most sporadic cases are inherited. Since this method does not seem to be completely reliable in recognizing XLI-carriers, the aim of the present study was to corroborate by FISH whether or not most sporadic cases of XLI had de novo mutations. XLI patients were classified through STS assay and PCR amplification of 5'-3' ends of the STS gene. XLI patients had undetectable levels of STS activity and complete deletion of the STS gene. Patients' mothers were studied through STS assay and FISH. Nine out of 12 mothers presented an STS activity compatible with XLI-carrier state. These mothers also had only one copy of the STS gene, indicating that they carry the primary gene defect. One mother had normal STS activity but only one copy of the STS gene. This data corroborated that most sporadic cases do not represent de novo mutations, and that FISH must be included in the analysis of mothers of sporadic cases when they present with normal STS activity, in order to correctly diagnose the XLI carrier state.

Deletion of exons 1-5 of the STS gene causing X-linked ichthyosis.

X-linked ichthyosis is an inherited disorder due to steroid sulfatase deficiency. It is clinically characterized by dark, adhesive, and regular scales of the skin. Most X-linked ichthyosis patients present large deletions of the STS gene and flanking markers; a minority show a point mutation or partial deletion of the STS gene. In this study we analyzed the STS gene in a family with simultaneous occurrence of X-linked ichthyosis and ichthyosis vulgaris. X-linked ichthyosis diagnosis was confirmed through steroid sulfatase assay in leukocytes using 7-[3H]-dehydroepiandrosterone sulfate as a substrate. Exons 1, 2, 5, and 6-10, and the 5' flanking markers DXS1130, DXS1139, and DXS996 of the STS gene were analyzed by polymerase chain reaction. X-linked ichthyosis patients of the family (n = 4 males) had undetectable levels of STS activity (0.00 pmol per mg protein per h). The DNA analysis showed that only exons 6-10 and the 5' flanking markers of the STS gene were present. We report the first partial deletion of the STS gene spanning exons 1-5 in X-linked ichthyosis patients.

Deletion pattern of the STS gene in X-linked ichthyosis in a Mexican population.

BACKGROUND: X-linked ichthyosis (XLI) is an inherited disorder due to steroid sulfatase deficiency (STS). Most XLI patients (>90%) have complete deletion of the STS gene and flanking sequences. The presence of low copy number repeats (G1.3 and CRI-S232) on either side of the STS gene seems to play a role in the high frequency of these interstitial deletions. In the present study, we analyzed 80 Mexican patients with XLI and complete deletion of the STS gene. MATERIALS AND METHODS: STS activity was measured in the leukocytes using 7-[(3)H]-dehydroepiandrosterone sulfate as a substrate. Amplification of the regions telomeric-DXS89, DXS996, DXS1139, DXS1130, 5' STS, 3' STS, DXS1131, DXS1133, DXS237, DXS1132, DXF22S1, DXS278, DXS1134-centromeric was performed through PCR. RESULTS: No STS activity was detected in the XLI patients (0.00 pmoles/mg protein/h). We observed 3 different patterns of deletion. The first two groups included 25 and 32 patients, respectively, in which homologous sequences were involved. These subjects showed the 5' STS deletion at the sequence DXS1139, corresponding to the probe CRI-S232A2. The group of 32 patients presented the 3' STS rupture site at the sequence DXF22S1 (probe G1.3) and the remaining 25 patients had the 3' STS breakpoint at the sequence DXS278 (probe CRI-S232B2). The third group included 23 patients with the breakpoints at several regions on either side of the STS gene. No implication of the homologous sequences were observed in this group. CONCLUSION: These data indicate that more complex mechanisms, apart from homologous recombination, are occurring in the genesis of the breakpoints of the STS gene of XLI Mexican patients.

Mutation report: a novel partial deletion of exons 2-10 of the STS gene in recessive X-linked ichthyosis.

X-linked ichthyosis is an inherited disease due to steroid sulfatase deficiency. Onset is at birth or early after birth with dark, regular, and adherent scales of skin. Approximately 85%-90% of X-linked ichthyosis patients have large deletions of the STS gene and flanking sequences. Three patients have been identified with partial deletions of the gene. Two deletions have been found at the 3' extreme and the other one implicating exons 2-5. This study describes a novel partial deletion of the STS gene in an X-linked ichthyosis patient. The subject was classified through steroid sulfatase assay in leukocytes using 7-[3H]-dehydroepiandrosterone sulfate as a substrate. Exons 1, 2, 5, and 7-10, and 3' flanking sequences DXS1131, DXS1133, DXS237, DXS1132, DXF22S1, and DXS278 of the STS gene were analyzed through polymerase chain reaction. The DNA analysis showed that exon 1 and 3' flanking sequences from DXS237 to DXS278 were present. In this study we report the fourth partial deletion of the STS gene and the first spanning exons 2-10 in X-linked ichthyosis patients.