Novel Mutations Including Deletions of the Entire OFD1 Gene in 30 Families with Type 1 Orofaciodigital Syndrome: A Study of the Extensive Clinical Variability

OFD1, now recognized as a ciliopathy, is characterized by malformations of the face, oral cavity and digits, and is transmitted as an X‐linked condition with lethality in males. Mutations in OFD1 also cause X‐linked Joubert syndrome (JBTS10) and Simpson–Golabi–Behmel syndrome type 2 (SGBS2). We have studied 55 sporadic and six familial cases of suspected OFD1. Comprehensive mutation analysis in OFD1 revealed mutations in 37 female patients from 30 families; 22 mutations have not been previously described including two heterozygous deletions spanning OFD1 and neighbouring genes. Analysis of clinical findings in patients with mutations revealed that oral features are the most reliable diagnostic criteria. A first, detailed evaluation of brain MRIs from seven patients with cognitive defects illustrated extensive variability with the complete brain phenotype consisting of complete agenesis of the corpus callosum, large single or multiple interhemispheric cysts, striking cortical infolding of gyri, ventriculomegaly, mild molar tooth malformation and moderate to severe cerebellar vermis hypoplasia. Although the OFD1 gene apparently escapes X‐inactivation, skewed inactivation was observed in seven of 14 patients. The direction of skewing did not correlate with disease severity, reinforcing the hypothesis that additional factors contribute to the extensive intrafamilial variability.     

Next-generation sequencing in X-linked intellectual disability

X-linked intellectual disability (XLID) is a genetically heterogeneous disorder with more than 100 genes known to date. Most genes are responsible for a small proportion of patients only, which has hitherto hampered the systematic screening of large patient cohorts. We performed targeted enrichment and next-generation sequencing of 107 XLID genes in a cohort of 150 male patients. Hundred patients had sporadic intellectual disability, and 50 patients had a family history suggestive of XLID. We also analysed a sporadic female patient with severe ID and epilepsy because she had strongly skewed X-inactivation. Target enrichment and high parallel sequencing allowed a diagnostic coverage of >10 reads for ~96% of all coding bases of the XLID genes at a mean coverage of 124 reads. We found 18 pathogenic variants in 13 XLID genes (AP1S2, ATRX, CUL4B, DLG3, IQSEC2, KDM5C, MED12, OPHN1, SLC9A6, SMC1A, UBE2A, UPF3B and ZDHHC9) among the 150 male patients. Thirteen pathogenic variants were present in the group of 50 familial patients (26%), and 5 pathogenic variants among the 100 sporadic patients (5%). Systematic gene dosage analysis for low coverage exons detected one pathogenic hemizygous deletion. An IQSEC2 nonsense variant was detected in the female ID patient, providing further evidence for a role of this gene in encephalopathy in females. Skewed X-inactivation was more frequently observed in mothers with pathogenic variants compared with those without known X-linked defects. The mutation rate in the cohort of sporadic patients corroborates previous estimates of 5–10% for X-chromosomal defects in male ID patients.     

Infrainguinal atherectomy: a retrospective review of a single-center experience

By decreasing plaque burden, atherectomy provides an alternative to angioplasty and stenting as a means of revascularizing patients with peripheral arterial disease. A new atherectomy device (SilverHawk) has recently been approved by the Food and Drug Administration, but the results with its use are unclear. We analyzed a series of consecutive patients undergoing atherectomy. We retrospectively reviewed the charts of 35 patients undergoing infrainguinal (IF) atherectomy in 38 limbs. The Trans-Atlantic Inter-Society Consensus (TASC) classification and Society of Vascular Surgery runoff scores were calculated. Time to event analysis was performed using Kaplan-Meier estimates. Risk factors affecting patency were analyzed with a multivariate Cox model. Mean patient age was 70 +/- 9.6 years. Indications for intervention were claudication (26%), rest pain (21%), and tissue loss (53%). Femoropopliteal (FP) atherectomy was performed in 68% and tibial atherectomy in 32%. For FP lesions, the TASC distribution was A, 42%; B, 23%; C, 4%; and D, 15%. The average lesion treatment length was 9.4 +/- 10.6 cm (range 1-40), and the runoff score was 5.1 +/- 3.5. For tibial lesions, the TASC distribution was A, 0%; B, 17%; C, 8%; and D, 75%. The average lesion treatment length was 9.2 +/- 6.0 cm (range 2-20), with a runoff score of 5.4 +/- 2.4. A total of 39% of patients had prior IF interventions. Adjunctive angioplasty of the atherectomized lesion was performed in 55% of cases, stenting in 0%, and adjunctive therapy for tandem lesions in 39%. The postoperative ankle-brachial index increased by 0.30 +/- 0.14 and toe pressures increased by 40 +/- 32.4 mm Hg. Mean follow-up was 10 +/- 8 months (range 0.3-23). During the studied period, seven patients required major limb amputation and five open surgical revascularization. Total primary and secondary patency rates were 66% and 70% at 1 year, respectively. Primary and secondary patency rates for FP atherectomy were 68% and 73% at 1 year, respectively. The limb salvage rate was 74% at 6 months. Patients with prior interventions in the atherectomized segment had an almost 10-fold decrease in primary patency. Atherectomy produces acceptable results, similar to those in reported series of conventional balloon angioplasty/stenting. Patients with prior IF interventions had a nearly 10-fold decrease in primary patency. A greater than sixfold decrease in patency rates was noted in patients who underwent simultaneous inflow or outflow procedures, but this finding did not reach statistical significance (p = 0.082). Future studies should focus on cost comparisons with other treatments such as angioplasty and stenting, and prospective randomized trials should be performed to compare these treatment alternatives.     

Creation of a novel hemodialysis bridge graft to extend the life of an adolescent

All conventional dialysis access options were exhausted in a 19-year-old girl with end-stage renal disease (ESRD). Her course was medically and psychosocially complicated. To save her life, a subclavian artery to right atrium hemodialysis bridge graft was created so that she could be dialyzed successfully. Adolescents and young adults confronted with the exhaustion of dialysis access and transplant options face extremely difficult management decisions. Attention to the multi-disciplinary needs of these patients and a combined effort by medical, surgical, psychological, and social work teams are necessary to address properly these dilemmas.     

Effects of age on balance control during walking

OBJECTIVE: To determine the effects of aging on balance control during walking. DESIGN: Two-group repeated-measures design. SETTING: Gait laboratory in Australia. PARTICIPANTS: Convenience sample of 20 healthy older subjects (mean age, 72y) and 20 healthy young subjects (mean age, 24y). INTERVENTIONS: Changes in locomotor performance in response to perturbations to balance were quantified for healthy older adults compared with healthy young adults for (1) straight line walking at preferred speed, (2) straight line walking at fast speed, (3) figure-of-eight walking at preferred speed, and (4) figure-of-eight walking while performing a secondary motor task. MAIN OUTCOME MEASURES: Gait speed, stride length, cadence, and double-limb support duration, using a footswitch system. RESULTS: Healthy older people screened for pathology had gait patterns comparable to young adults for straight line walking at preferred speed. However, multivariate analysis of variance (MANOVA) showed a significant interaction between age and speed when balance was perturbed by requiring subjects to change from walking at preferred to fast speeds (Pillai-Bartlett trace=.259, F(4,35)=3.06, P<.029, partial eta(2)=.259). This occurred because older people did not increase their speed (F(1,38)=7.65, P<.01, partial eta(2)=.168) or stride length (F(1,38)=12.23, P<.01, partial eta(2)=.243) as much as did the young adults. MANOVAs did not show statistically significant interactions between age and turning conditions or age and dual task conditions, although older people walked more slowly and with shorter steps when turning or performing a secondary task. CONCLUSIONS: Balance strategies during gait are task specific and vary according to age. In response to challenges to balance imposed by the requirement to change from preferred to fast walking, older people did not increase their speed and stride length to the same extent as did younger adults. This was possibly a strategy to maintain their stability.     

RPE cells internalize low-density lipoprotein (LDL) and oxidized LDL (oxLDL) in large quantities in vitro and in vivo

PURPOSE: To determine whether plasma low-density lipoprotein (LDL) could be internalized by the RPE and which receptors may be involved. A secondary objective was to determine whether ARPE19 cells could be used as a model to investigate cholesterol processing in the RPE. METHODS: Commercially available human LDL was labeled with rhodamine or AlexaFluor 568. Immunofluorescence was performed using commercially available antibodies to LDL-R, CD36, and LOX-1. Cells and tissues were imaged using epifluorescence and confocal fluorescence microscopy. Immunoblot analysis and RT-PCR were performed using published techniques. RESULTS: Intravenously injected rhodamine-labeled LDL (rhoLDL) was detected in the rat RPE by fluorescence confocal microscopy 24 hours after injection. The rhoLDL was present in some areas and absent in others. Cultured ARPE19 cells were also found to internalize LDL and oxidized LDL (oxLDL) readily. Using AlexaFluor 568-labeled LDL we determined that the average cultured RPE cell could internalize approximately 12 to 16 pg of LDL and oxLDL in 24 hours. Immunoblots readily detected the presence of CD36 and LDL-R in the cultured RPE cells but not LOX-1, whereas RT-PCR detected mRNA for all three receptors. Dual-labeling experiments using AlexaFluor 568-labeled LDL and AlexaFluor 488 for the immunolocalization of the receptors showed colocalization of LDL-R with the internalized LDL and CD36 with oxLDL particles. CONCLUSIONS: Plasma LDL readily enters the RPE through the choriocapillaris but is not found homogeneously throughout the retina. This may suggest some form of regulation to the permeability of the fenestrated choroidal endothelial cell junctions. ARPE19 cells are a good model for studying the internalization mechanisms of LDL and oxLDL in vitro. LDL may be used as a vector to carry hydrophobic molecules into the RPE.     

Russian electrical stimulation: the early experiments

Russian forms of electrical stimulation became popular to a large extent as a result of the activities of Kots, who claimed force gains of up to 40% in elite athletes as a result of what was then a new form of stimulation. He did not provide details of his published work, nor did he give references. Russian electrical stimulation became popular despite the lack of research in the English-language literature. No studies published in English examined whether the "10/50/10" treatment regimen (10 seconds of stimulation followed by 50 seconds rest, repeated for 10 minutes) advocated by Kots is optimal, and only one study addressed whether maximum muscle torque was produced at an alternating current frequency of 2.5 kHz. The few studies that compared low-frequency monophasic pulsed current and Russian electrical stimulation are inconclusive. This article reviews and provides details of the original studies by Kots and co-workers. The authors contend that these studies laid the foundations for the use of Russian forms of electrical stimulation in physical therapy. The authors conclude that there are data in the Russian-language literature that support the use of Russian electrical stimulation but that some questions remain unanswered.