Transgenic Rescue of the LARGEmyd Mouse: A LARGE Therapeutic Window?

LARGE is a glycosyltransferase involved in glycosylation of α-dystroglycan (α-DG). Absence of this protein in the LARGEmyd mouse results in α-DG hypoglycosylation, and is associated with central nervous system abnormalities and progressive muscular dystrophy. Up-regulation of LARGE has previously been proposed as a therapy for the secondary dystroglycanopathies: overexpression in cells compensates for defects in multiple dystroglycanopathy genes. Counterintuitively, LARGE overexpression in an FKRP-deficient mouse exacerbates pathology, suggesting that modulation of α-DG glycosylation requires further investigation. Here we demonstrate that transgenic expression of human LARGE (LARGE-LV5) in the LARGEmyd mouse restores α-DG glycosylation (with marked hyperglycosylation in muscle) and that this corrects both the muscle pathology and brain architecture. By quantitative analyses of LARGE transcripts we also here show that levels of transgenic and endogenous LARGE in the brains of transgenic animals are comparable, but that the transgene is markedly overexpressed in heart and particularly skeletal muscle (20–100 fold over endogenous). Our data suggest LARGE overexpression may only be deleterious under a forced regenerative context, such as that resulting from a reduction in FKRP: in the absence of such a defect we show that systemic expression of LARGE can indeed act therapeutically, and that even dramatic LARGE overexpression is well-tolerated in heart and skeletal muscle. Moreover, correction of LARGEmyd brain pathology with only moderate, near-physiological LARGE expression suggests a generous therapeutic window

GGPS1 mutations cause muscular dystrophy/hearing loss/ovarian insufficiency syndrome

Objective A hitherto undescribed phenotype of early onset muscular dystrophy associated with sensorineural hearing loss and primary ovarian insufficiency was initially identified in 2 siblings and in subsequent patients with a similar constellation of findings. The goal of this study was to understand the genetic and molecular etiology of this condition. Methods We applied whole exome sequencing (WES) superimposed on shared haplotype regions to identify the initial biallelic variants in GGPS1 followed by GGPS1 Sanger sequencing or WES in 5 additional families with the same phenotype. Molecular modeling, biochemical analysis, laser membrane injury assay, and the generation of a Y259C knock‐in mouse were done. Results A total of 11 patients in 6 families carrying 5 different biallelic pathogenic variants in specific domains of GGPS1 were identified. GGPS1 encodes geranylgeranyl diphosphate synthase in the mevalonate/isoprenoid pathway, which catalyzes the synthesis of geranylgeranyl pyrophosphate, the lipid precursor of geranylgeranylated proteins including small guanosine triphosphatases. In addition to proximal weakness, all but one patient presented with congenital sensorineural hearing loss, and all postpubertal females had primary ovarian insufficiency. Muscle histology was dystrophic, with ultrastructural evidence of autophagic material and large mitochondria in the most severe cases. There was delayed membrane healing after laser injury in patient‐derived myogenic cells, and a knock‐in mouse of one of the mutations (Y259C) resulted in prenatal lethality. Interpretation The identification of specific GGPS1 mutations defines the cause of a unique form of muscular dystrophy with hearing loss and ovarian insufficiency and points to a novel pathway for this clinical constellation

Pre-counseling education for low literacy women at risk of Hereditary Breast and Ovarian Cancer (HBOC): patient experiences using the Cancer Risk Education Intervention Tool (CREdIT).

The Cancer Risk Education Intervention Tool (CREdIT) is a computer-based (non-interactive) slide presentation designed to educate low-literacy, and ethnically and racially diverse public hospital patients at risk of Hereditary Breast and Ovarian Cancer (HBOC) about genetics. To qualitatively evaluate participants' experience with and perceptions of a genetic education program as an adjunct to genetic counseling, we conducted direct observations of the intervention, semi-structured in person interviews with 11 women who viewed CREdIT, and post-counseling questionnaires with the two participating genetic counselors. Five themes emerged from the analysis of interviews: (1) genetic counseling and testing for breast/ovarian cancer was a new concept; (2) CREdIT's story format was particularly appealing; (3) changes in participants' perceived risk for breast cancer varied; (4) some misunderstandings about individual risk and heredity persisted after CREdIT and counseling; (5) the context for viewing CREdIT shaped responses to the presentation. Observations demonstrated ways to make the information provided in CREdIT and by genetic counselors more consistent. In a post-session counselor questionnaire, counselors' rating of the patient's preparedness before the session was significantly higher for patients who viewed CREdIT prior to their appointments than for other patients. This novel educational tool fills a gap in HBOC education by tailoring information to women of lower literacy and diverse ethnic/racial backgrounds. The tool was well received by interview participants and counselors alike. Further study is needed to examine the varied effects of CREdIT on risk perception. In addition, the implementation of CREdIT in diverse clinical settings and the cultural adaptation of CREdIT to specific populations reflect important areas for future work