Molecular study of the rhodopsin gene in retinitis pigmentosa patients in the Basque Country.

Retinitis pigmentosa (RP) is a degenerative disorder affecting the outer segment of the retina and leading to night blindness and progressive visual field loss. The rhodopsin gene encodes a photolabile pigment located in the rod outer segments constituting around 80-90% of its protein content and is the initiation point for the visual cascade upon absorption of a single photon. Seventy-five unrelated, isolated RP families in the Basque Country, with at least one affected member, were diagnosed at our hospital after ophthalmic examination and electroretinogram analysis. The patients received genetic counselling according to their individual case based on their clinical diagnosis. The modes of inheritance found from pedigree studies were the following: 20% (15/75) were classified as autosomal dominant retinitis pigmentosa (ADRP), 17.33% (13/75) were autosomal recessive (ARRP), 2.66% (2/75) were unclassified (NC), and 60% (45/75) were sporadic cases (SCRP). From these families, 75 unrelated and affected index cases together with 22 affected relatives and 42 unaffected relatives were screened for mutations in the rhodopsin gene by GC clamped denaturing gradient gel electrophoresis. Our results showed that five ADRP, three ARRP, 15 SCRP, and one NC families had alterations in this gene. Only three of these alterations, that is 4% (3/75) (95% CL 0-8), appeared to be responsible for the disease. This represents a lower percentage than the 10% previously reported.

[Interstitial deletion of the long arms of chromosome 13]. / Un caso de delección intersticial del brazo largo del cromosoma 13.

We present a case of a child with important phenotypic abnormalities (retinoblastoma, hypoplasia of the thumbs and genital), as well as craneofacial and evident psychomotor retardation. The chromosomal study showed a interstitial delection of the long arms of a chromosome from D group. We try to correlate karyotypes and phenotype, telling about difficulties that this relation means insisting about the importance of knowing more cases of chromosome 13 delection. We also think that subbands analysis represents an important factor in this correlation.