Navigating the White Dot Syndromes with Optical Coherence Tomography (OCT) and OCT Angiography (OCT-A).

INTRODUCTION: White dot syndromes are a heterogeneous group of diseases that affect different layers in the retina and choroid. Multimodal imaging is fundamental in the diagnosis, but also can be crucial in unveiling the pathogenesis of these entities. MATERIAL AND METHODS: Literature review. RESULTS: Optical coherence tomography (OCT) provides depth-resolved, histological grade images of the vitreous, retina, and choroid. This technology is very useful to localize the primary nature and level of pathology of the various white dot syndromes. En face OCT can provide additional information regarding the interrelationship of lesion types. Vascular involvement at the level of the retina, choriocapillaris or choroid can be assessed by en face OCT angiography (OCT-A) and is not limited by masking, leakage or staining as can occur with conventional angiography (fluorescein or indocyanine green angiography) which requires dye injection. CONCLUSION: OCT and OCTA are fundamental in the diagnosis and follow-up of white dots syndromes.

Response to selection from new mutation and effective size of partially inbred populations. II. Experiments with Drosophila melanogaster.

Divergent artificial selection for abdominal bristle number in Drosophila melanogaster has been carried out starting from a genetically homogeneous base population. Lines with two different systems of mating, random (P lines) or between full sibs whenever possible (about 50%), random otherwise (I lines) were compared. Responses after 40 generations of selection were mostly due to one or two mutations of large effect (0.2 to 2 phenotypic standard deviations) per line. Ten mutations affecting the selected trait were individually studied (five lethal and five non-lethal, these being predominantly additive). These mutations satisfactorily explain the response attained, although some minor mutations may also be involved. No evidence of epistasis for bristle number was found. The average final divergence was 57% larger in the P lines, but it was mostly due to lethals or highly deleterious mutations. Thus, after relaxation of selection, the ranking reversed and the mean divergence became significantly larger in the I lines (14%). Analysis of inbreeding showed that the very small amount of variation created by spontaneous mutations (a heritability for the selected trait of about 3%) was responsible for a reduction in the effective size of about 50% in the I lines (relative to the case with random selection), but only about 10% in the P lines. Mutational heritabilities estimated from the response to selection (0.05-0.18%) were within the range usually found for this trait in previous experiments. REML estimates account for correlations between relatives, and were much larger in those lines where the response was due to lethal mutations, as these do not contribute to response after reaching maximum frequency.