Molecular analysis of the CTNS gene in Jordanian families with nephropathic cystinosis / Análisis molecular del gen CTNS en familias jordanas afectadas por cistinosis nefropática

Objetivo: La cistinosis nefropática es una enfermedad de almacenamiento lisosómico autosómica recesiva que se caracteriza por la acumulación del aminoácido cistina en varios tejidos del cuerpo. Ello se debe a una mutación en el gen CTNS, que codifica la proteína cistinosina. El objetivo de este estudio fue secuenciar los exones codificantes del gen CTNS en cinco familias jordanas afectadas por la cistinosis. Métodos: Los casos índice se presentaron inicialmente con síntomas del síndrome de Fanconi. Exámenes oftalmológicos revelaron la acumulación de cristales de cistina en la córnea a la edad de 2 años, lo que sugería la existencia de cistinosis. Todos los exones codificantes, las secuencias intrónicas flanqueantes y la región promotora del gen CTNS se amplificaron mediante reacción en cadena de la polimerasa y fueron objeto de secuenciación. Resultados: Ninguno de los casos índice de este estudio presentaba la deleción 57-kb europea en el gen CTNS. Se identificaron siete variantes en las secuencias codificante y promotora del gen CTNS en los casos índice de este estudio. Dos de estas variantes eran una mutación del gen CTNS previamente identificada en un genotipo heterocigótico de dos pacientes de descendencia europea. Las dos mutaciones eran c.829dupA en el exón 10 y c.890G>A en el exón 11. El caso índice de la familia número 2 era heterocigótico compuesto respecto a las dos mutaciones. Conclusión: El presente estudio es el primer estudio molecular sobre cistinosis nefropática infantil en Jordania. Logramos identificar con éxito las mutaciones en el gen CTNScausante en familias jordanas. Los resultados sirven de base para la detección precoz de esta enfermedad mediante herramientas moleculares en una población jordana marcadamente consanguínea (AU)

Objective: Nephropathic cystinosis is an autosomal recessive lysosomal storage disorder that is characterised by the accumulation of the amino acid cystine in several body tissues due to a mutation in the CTNS gene, which encodes the cystinosin protein. The aim of this study was to sequence the coding exons of the CTNS gene in five different Jordanian families and one family from Sudan with nephropathic cystinosis. Methods: Probands initially presented with Fanconi syndrome symptoms. An eye examination showed the accumulation of cystine crystals in the cornea by the age of 2 years, suggesting cystinosis. All of the coding exons and flanking intronic sequences and the promoter region of the CTNS gene were amplified using polymerase chain reaction and subjected to sequencing. Results: None of the probands in this study carried the European 57-kb deletion in the CTNS gene. Seven variants in the coding and promoter sequence of the CTNS gene were identified in the probands of this study. Two of these variants were a CTNS mutation that was previously identified in a heterozygous genotype in two different patients of European descendant. The two mutations were c.829dupA in exon 10 and c.890G>A in exon 11. The proband of family 2 was compound-heterozygous for the two mutations. Conclusion: This study is the first molecular study of infantile nephropathic cystinosis in Jordan. We successfully identified the causative CTNS mutations in Jordanian families. The results provide a basis for the early detection of the disease using molecular tools in a highly consanguineous Jordanian population (AU)

Molecular analysis of the CTNS gene in Jordanian families with nephropathic cystinosis.

OBJECTIVE: Nephropathic cystinosis is an autosomal recessive lysosomal storage disorder that is characterised by the accumulation of the amino acid cystine in several body tissues due to a mutation in the CTNS gene, which encodes the cystinosin protein. The aim of this study was to sequence the coding exons of the CTNS gene in five different Jordanian families and one family from Sudan with nephropathic cystinosis. METHODS: Probands initially presented with Fanconi syndrome symptoms. An eye examination showed the accumulation of cystine crystals in the cornea by the age of 2 years, suggesting cystinosis. All of the coding exons and flanking intronic sequences and the promoter region of the CTNS gene were amplified using polymerase chain reaction and subjected to sequencing. RESULTS: None of the probands in this study carried the European 57-kb deletion in the CTNS gene. Seven variants in the coding and promoter sequence of the CTNS gene were identified in the probands of this study. Two of these variants were a CTNS mutation that was previously identified in a heterozygous genotype in two different patients of European descendant. The two mutations were c.829dupA in exon 10 and c.890G>A in exon 11. The proband of family 2 was compound-heterozygous for the two mutations. CONCLUSION: This study is the first molecular study of infantile nephropathic cystinosis in Jordan. We successfully identified the causative CTNS mutations in Jordanian families. The results provide a basis for the early detection of the disease using molecular tools in a highly consanguineous Jordanian population.

Cyclosporine-a therapy in steroid dependent nephrotic syndrome: experience in amman, jordan.

The use of Cyclosporin-A (CsA) has been well described and is currently recommended for use in patients with steroid dependent nephrotic syndrome (SDNS), especially when they start having steroid side effects. Over a three-year period, a total of 10 patients diagnosed as having SNDS at the King Hussein Medical Center, Amman, Jordan were retrospectively studied. Their mean age was 9.53 +/- 4.9 years. All patients included in the study failed to maintain long-term remission following cyclophosphamide therapy and had all manifested at least one steroid side effect prior to the introduction of CsA. Kidney biopsy was performed on all patients and all had normal renal functions prior to the introduction of CsA. After inducing remission with conventional steroid therapy, CsA was given in a dose of 4-6 mg/Kg/day orally in two divided doses and adjusted to maintain a mean blood trough level between 100 and 150 ng/ml. Total duration of therapy ranged between six and 24 months with a mean of 17 +/- 7.7. Steroid therapy was stopped in all patients within two months of starting CsA. Four patients relapsed after 4-6 months of stopping steroids. However, remission was re-induced when low dose alternate day prednisolone therapy was added. Two patients relapsed four months after stopping CsA, which was given for 24 months. Our study suggests that CsA is effective in maintaining long-term remission and decreasing steroid requirements in patients with SDNS.