Examining Whether AOSLO-Based Foveal Cone Metrics in Achromatopsia and Albinism Are Representative of Foveal Cone Structure

Purpose: Adaptive optics scanning light ophthalmoscopy (AOSLO) imaging in patients with achromatopsia (ACHM) and albinism is not always successful. Here, we tested whether optical coherence tomography (OCT) measures of foveal structure differed between patients for whom AOSLO images were either quantifiable or unquantifiable. Methods: The study included 166 subjects (84 with ACHM; 82 with albinism) with previously acquired OCT scans, AOSLO images, and best-corrected visual acuity (BCVA, if available). Foveal OCT scans were assessed for outer retinal structure, outer nuclear layer thickness, and hypoplasia. AOSLO images were graded as quantifiable if a peak cone density could be measured and/or usable if the location of peak density could be identified and the parafoveal mosaic was quantifiable. Results: Forty-nine percent of subjects with ACHM and 57% of subjects with albinism had quantifiable AOSLO images. Older age and better BCVA were found in subjects with quantifiable AOSLO images for both ACHM (P = 0.0214 and P = 0.0276, respectively) and albinism (P = 0.0073 and P < 0.0004, respectively). There was a significant trend between ellipsoid zone appearance and ability to quantify AOSLO (P = 0.0028). In albinism, OCT metrics of cone structure did not differ between groups. Conclusions: Previously reported AOSLO-based cone density measures in ACHM may not necessarily reflect the degree of remnant cone structure in these patients. Translational Relevance: Until AOSLO is successful in all patients with ACHM and albinism, the possibility of the reported data from a particular cohort not being representative of the entire population remains an important issue to consider when interpreting results from AOSLO studies

Whole exome sequencing in dominant cataract identifies a new causative factor, CRYBA2, and a variety of novel alleles in known genes.

Pediatric cataracts are observed in 1-15 per 10,000 births with 10-25 % of cases attributed to genetic causes; autosomal dominant inheritance is the most commonly observed pattern. Since the specific cataract phenotype is not sufficient to predict which gene is mutated, whole exome sequencing (WES) was utilized to concurrently screen all known cataract genes and to examine novel candidate factors for a disease-causing mutation in probands from 23 pedigrees affected with familial dominant cataract. Review of WES data for 36 known cataract genes identified causative mutations in nine pedigrees (39 %) in CRYAA, CRYBB1, CRYBB3, CRYGC (2), CRYGD, GJA8 (2), and MIP and an additional likely causative mutation in EYA1; the CRYBB3 mutation represents the first dominant allele in this gene and demonstrates incomplete penetrance. Examination of crystallin genes not yet linked to human disease identified a novel cataract gene, CRYBA2, a member of the \u3b2\u3b3-crystallin superfamily. The p.(Val50Met) mutation in CRYBA2 cosegregated with disease phenotype in a four-generation pedigree with autosomal dominant congenital cataracts with incomplete penetrance. Expression studies detected cryba2 transcripts during early lens development in zebrafish, supporting its role in congenital disease. Our data highlight the extreme genetic heterogeneity of dominant cataract as the eleven causative/likely causative mutations affected nine different genes, and the majority of mutant alleles were novel. Furthermore, these data suggest that less than half of dominant cataract can be explained by mutations in currently known genes

Vitamin K, an update for the paediatrician

This review summarizes current knowledge on vitamin K for the paediatrician. Vitamin K is a fat-soluble vitamin, present in plants as phylloquinone and produced by bacteria as menaquinone. It is acting as a co-factor for gamma-glutamyl carboxylase. This enzyme is responsible for post-translational modification of some glutamate side chains to gamma-carboxyglutamate. The majority of gamma-carboxylated proteins function in blood coagulation; others play a role in calcium homeostasis. Newborn babies are at particular risk of vitamin K deficiency, as placental transfer is limited and human milk is a poor source. Vitamin K prophylaxis at birth effectively prevents vitamin K deficiency bleeding (VKDB), formerly known as "haemorrhagic disease of the newborn". Recent epidemiological studies provide data on the effectiveness of different administration routes and dosing schemes. Infants of mothers taking drugs that inhibit vitamin K are at risk of early VKDB and should receive 1 mg intramuscular (IM) as soon as possible after birth. Classic VKDB is prevented by intramuscular as well as by oral administration of 1 mg vitamin K. In exclusively breast-fed infants, single IM administration at birth is also effectively preventing (rare) late VKDB but single oral administration is not. If given orally, prophylaxis should be continued by either weekly administration of 1 mg till 12 weeks or repeating 2 mg at weeks 1 and 4. Daily administration of 25 mu g offers insufficient protection. The only infants not fully protected in this way are those with yet unrecognised liver disease. Further work is needed before firm recommendations can be made regarding dose in preterm infants and in patients with fat malabsorption/cholestasis or regarding the role of vitamin K in the prevention of osteoporosis