The c.156_157insAlu BRCA2 mutation has so far only been reported in hereditary breast/ovarian cancer (HBOC) families of Portuguese origin. Since this mutation is not detectable using the commonly used screening methodologies and must be specifically sought, we screened for this rearrangement in a total of 5,440 suspected HBOC families from 22 labs from 13 countries from several continents. Whereas the c.156_157insAluBRCA2 mutation was detected in 11 of 149 suspected HBOC families from Portugal, representing 37.9% of all deleterious mutations, in other countries it was detected only in one proband living in France and in four individuals requesting predictive testing living in France and in the USA, all having in common the fact that they are relatively recent immigrants of Portuguese origin in those countries. After performing an extensive haplotype study in carrier families, we estimate that this founder mutation has occurred 558±215 years ago. We further demonstrate significant quantitative differences regarding the production of the BRCA2 full length RNA and the transcript with exon 3 skipping in c.156_157insAlu BRCA2 mutation carriers and in controls, indicating that disruption of alternative transcript ratios is the mechanism causing hereditary breast/ovarian cancer associated with this BRCA2 rearrangement. We further show that the cumulative incidence of breast cancer in c.156_157insAlu BRCA2 mutation carriers does not differ from that of other BRCA2 and BRCA1 pathogenic mutations, further strengthening its role as the major contributor to hereditary predisposition to breast cancer in Portugal. We recommend that all suspected HBOC families from Portugal or with Portuguese ancestry are specifically tested for this rearrangement, ideally prior to screening of the entire coding regions of BRCA1 and BRCA2.3

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Our findings are consistent with those reported by other published series. We therefore conclude that the probability of having pathological results in array-CGH increases with the presence of any of the features mentioned above in patients with ID/GDD.

Presentación de casos clínicos RESUMENEl síndrome renal-coloboma es una enfermedad autosómica dominante caracterizada por hipodisplasia renal y coloboma. Se presenta el caso de una niña de 12 años afecta de enfermedad renal crónica, colobomas papilares bilaterales y mutación excepcional del gen PAX-2. Con diagnóstico prenatal de hipoplasia renal bilateral, a los 5 días de vida, presentó clínica y datos analíticos compatibles con enfermedad renal crónica. En los controles posteriores, se apreció reflujo vesicoureteral grado ii bilateral, que se resolvió espontáneamente, proteinuria mantenida en rango no nefrótico controlada con enalapril y colobomas bilaterales con atrofia macular izquierda. La función renal se mantuvo estable. El estudio genético demostró mutación p.R104X de novo sin sentido en heterocigosis. Globalmente, existen documentados 80 casos de síndrome renalcoloboma asociado a mutaciones de este gen. Las evaluaciones oftalmológicas y genéticas son fundamentales en los casos de hipodisplasia renal. La función renal determinará el pronóstico. Se realizó una revisión bibliográfica de la etiopatogenia de la enfermedad. Palabras clave: coloboma de nervio óptico, síndrome papilorrenal, PAX2. ABSTRACTRenal-coloboma syndrome is an autosomal dominant disease characterized by renal hypodysplasia and coloboma. A case of a 12-year-old girl with chronic kidney disease, bilateral optic nerve colobomas and an exceptional PAX-2 gene mutation is presented. Diagnosed in prenatal scans with bilateral renal hypoplasia, she presented clinical and laboratory findings of chronic kidney disease at 5 days of life. Following tests Mutación infrecuente en el síndrome renal-coloboma: a propósito de un caso y revisión Infrequent mutation in renal-coloboma syndrome: case report and reviewshowed grade II bilateral vesicoureteral reflux spontaneously solved, maintained non nephrotic proteinuria controlled with enalapril and bilateral colobomas with left macular atrophy. Renal function remained stable. Genetic study showed de novo and non sense mutation p.R104X in heterocygosis. Currently there are 80 published cases of renal-coloboma syndrome associated with this gene mutations. Ophthalmologic and genetic evaluations are crucial in cases affected by renal hypodysplasia. Renal function will establish prognosis. We review the etiopathogenesis of this disease.

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