A homozygous POC1B variant causes recessive cone-rod dystrophy.

Purpose: To report a case of initial cone dystrophy that advanced to a cone-rod dystrophy with homozygous variants in the POC1B gene.Methods: Retinal structure and visual function assessments were performed using fundoscopy, spectral-domain optical coherence tomography, full field electroretinography, semi-kinetic perimetry, and Ishihara plate testing. A DNA sample was collected and sent for diagnostic molecular genetic testing with a cone-rod dystrophy panel.Results: Clinical examination and electroretinography confirmed a clinical diagnosis of cone dystrophy. Molecular genetic testing revealed homozygous variants in POC1B (c.1355 G > A, p.(Arg452Gln)). Follow-up three years later showed progression to a cone-rod dystrophy.Conclusion: Our case describes an ophthalmological phenotype associated with a homozygous POC1B missense variant and provides clinical support for variant classification.

Sickle cell trait newborn screen results: disclosure and management.

This study aims to evaluate the notification process of sickle cell trait (SCT) identified by newborn screening in Alberta. On April 1, 2019, Alberta began newborn screening for sickle cell disease (SCD) and elected to report sickle cell trait (SCT). For 1 year, healthcare providers (HCPs) were sent a questionnaire which addressed the perceived importance of disclosing the SCT results, whether HCPs felt competent in disclosing the result, knowledge of available resources, and comfort with coordinating and interpreting testing for the newborn's parents. As a control, we collected data from HCPs receiving positive cystic fibrosis (CF) newborn screen results. A total of 107 out of 203 SCT questionnaires were returned and 41 of 66 CF questionnaires were returned. Respondents felt it was important that the results be shared with families (98% and 100%, respectively). Most respondents felt competent (SCT: 95%; CF: 85%), and willing to disclose the result to the family (SCT: 92%; CF: 88%). Fewer respondents were comfortable interpreting the results (SCT: 70%; CF: 51%)), and willing to arrange parental testing (SCT: 61%; CF: 59%). Family practitioners were significantly more willing to arrange SCT parental testing (88%) compared to pediatricians (40%) (OR = 5.3; CI 1.9, 15.4; p < 0.001). HCP comments revealed two themes: referral to another HCP for follow-up and identification of the primary HCP. Results support this disclosure process, and HCPs felt comfortable following up with SCT newborn screen results. The study identified challenges such as pediatricians being less comfortable ordering parental testing and the ordering HCP not always being the primary care provider.

The Axenfeld-Rieger Syndrome Gene FOXC1 Contributes to Left-Right Patterning.

Precise spatiotemporal expression of the Nodal-Lefty-Pitx2 cascade in the lateral plate mesoderm establishes the left-right axis, which provides vital cues for correct organ formation and function. Mutations of one cascade constituent PITX2 and, separately, the Forkhead transcription factor FOXC1 independently cause a multi-system disorder known as Axenfeld-Rieger syndrome (ARS). Since cardiac involvement is an established ARS phenotype and because disrupted left-right patterning can cause congenital heart defects, we investigated in zebrafish whether foxc1 contributes to organ laterality or situs. We demonstrate that CRISPR/Cas9-generated foxc1a and foxc1b mutants exhibit abnormal cardiac looping and that the prevalence of cardiac situs defects is increased in foxc1a-/-; foxc1b-/- homozygotes. Similarly, double homozygotes exhibit isomerism of the liver and pancreas, which are key features of abnormal gut situs. Placement of the asymmetric visceral organs relative to the midline was also perturbed by mRNA overexpression of foxc1a and foxc1b. In addition, an analysis of the left-right patterning components, identified in the lateral plate mesoderm of foxc1 mutants, reduced or abolished the expression of the NODAL antagonist lefty2. Together, these data reveal a novel contribution from foxc1 to left-right patterning, demonstrating that this role is sensitive to foxc1 gene dosage, and provide a plausible mechanism for the incidence of congenital heart defects in Axenfeld-Rieger syndrome patients.