An immune tolerance approach using transient low-dose methotrexate in the ERT-naïve setting of patients treated with a therapeutic protein: experience in infantile-onset Pompe disease.

PURPOSE: To investigate immune tolerance induction with transient low-dose methotrexate (TLD-MTX) initiated with recombinant human acid α-glucosidase (rhGAA), in treatment-naïve cross-reactive immunologic material (CRIM)-positive infantile-onset Pompe disease (IOPD) patients. METHODS: Newly diagnosed IOPD patients received subcutaneous or oral 0.4 mg/kg TLD-MTX for 3 cycles (3 doses/cycle) with the first 3 rhGAA infusions. Anti-rhGAA IgG titers, classified as high-sustained (HSAT; ≥51,200, ≥2 times after 6 months), sustained intermediate (SIT; ≥12,800 and <51,200 within 12 months), or low (LT; ≤6400 within 12 months), were compared with those of 37 CRIM-positive IOPD historic comparators receiving rhGAA alone. RESULTS: Fourteen IOPD TLD-MTX recipients at the median age of 3.8 months (range, 0.7-13.5 months) had a median last titer of 150 (range, 0-51,200) at median rhGAA duration ~83 weeks (range, 36-122 weeks). One IOPD patient (7.1%) developed titers in the SIT range and one patient (7.1%) developed titers in the HSAT range. Twelve of the 14 patients (85.7%) that received TLD-MTX remained LT, versus 5/37 HSAT (peak 51,200-409,600), 7/37 SIT (12,800-51,000), and 23/37 LT (200-12,800) among comparators. CONCLUSION: Results of TLD-MTX coinitiated with rhGAA are encouraging and merit a larger longitudinal study.

Pierpont syndrome associated with the p.Tyr446Cys missense mutation in TBL1XR1.

We present a 7-year old male with severe delays, hypotonia and dysmorphic features who had striking, deep palmar and plantar creases and pillowing of the soft tissues of the palms and soles. His facial features included a high anterior hairline, small eyes with narrowed palpebral fissures, a bulbous nasal tip with a short columella, and a large mouth with a thin upper vermilion, and small chin. He had a submucous cleft palate, bilateral cryptorchidism and hydronephrosis. Cranial imaging demonstrated an Arnold Chiari malformation that was also present in his maternal uncle by report. Exome sequencing revealed a de novo heterozygous sequence variant, p.Tyr446Cys, in TBL1XR1 that has previously been reported in six patients with Pierpont syndrome. This sequence variant occurs in the carboxy-terminal, WD40 domain of the protein. As TBL1XR1 is a critical component of the NCoR/SMRT co-repressor complex and the WD40 repeats are hypothesized to interact with histone H2B and H4, the mutation may impact protein interactions necessary for stabilizing the complex with chromatin. De novo missense and frameshift mutations and deletions involving TBL1XR1 have been described in patients with intellectual disability and autism, but without any of the dysmorphic findings or malformations associated with Pierpont syndrome, implying a mutation-specific mechanism for the pathogenicity of p.Tyr446Cys. Our case is the first individual with this mutation to have a submucous cleft palate and hydronephrosis, although his severe delays, hypotonia, dysmorphic findings and emerging scoliosis appear consistent with previous reports. His distinctive facial and digital features are further evidence that p.Tyr446Cys results in a clinically recognizable, syndromic form of intellectual disability in contrast to other TBL1XR1 mutations.

Corneal clouding, cataract, and colobomas with a novel missense mutation in B4GALT7-a review of eye anomalies in the linkeropathy syndromes.

We present a 5-year-old female with a distinctive phenotype comprising global developmental delays, pre- and post-natal growth restriction, striking joint laxity with soft skin, and scoliosis. She had a triangular facies, a prominent forehead, proptosis, a small nose, and a small jaw. Her ocular findings included corneal clouding, colobomas of the iris and optic nerve, and posterior subcapsular cataracts. Exome sequencing identified homozygosity for c.970T>A, predicting p.(Cys324Ser), in the xylosylprotein 4-beta-galactosyltransferase, polypeptide 7 (B4GALT7) gene. Variant segregation was consistent with autosomal recessive inheritance and the missense substitution was predicted to be pathogenic. As the phenotype of this child is consistent with that described in other "linkeropathy" syndromes, we conclude that p.(Cys324Ser) is likely to be disease-causing. The eye features were a notable part of this child's presentation and mutations in the linkeropathy genes (XYLT1, XYLT2, B4GALT7, B3GALT6, and B3GAT3) can be associated with ocular findings, including blue sclerae, refractive errors, corneal clouding, strabismus, nystagmus, cataracts, glaucoma, and retinal abnormalities, including retinal detachment. The corneal clouding and cataracts in this patient may thus have been caused by her B4GALT7 mutation, but the colobomas are a novel phenotypic finding. However, a different genetic etiology or a role for modifying genetic factors has not been excluded in the etiology of her colobomas. © 2016 Wiley Periodicals, Inc.

International genetic counseling students' perspective on their training experience in the United States.

International students face social, psychological and academic challenges upon moving to a foreign country to pursue higher education. Clinical disciplines such as genetic counseling present additional challenges adapting to an unfamiliar health care system and different interactions and expectations with patients and colleagues. This study used semi-structured interviews to identify challenges that international genetic counseling students face during training in the United States. Eight international genetic counseling alumni who graduated from U.S.-accredited programs were interviewed. Participants stated that the U.S. academic system was unfamiliar-class participation and paper-writing required the greatest adjustment. There was a need for help in understanding social norms in academic settings. Clinically, they were unfamiliar with the dynamics and communication style of U.S. families. Non-native English speakers experienced greater difficulty in all areas. Most participants reported that they were uncomfortable asking for help in transitioning to life, study and work. Participants identified mentorship programs for international students as potentially useful in clarifying expectations in academic and clinical settings. These results may assist international students preparing to study genetic counseling in the U.S. and may help genetic counseling training programs identify the academic and clinical challenges faced by international students.

Discrete change in volatile anesthetic sensitivity in mice with inactivated tandem pore potassium ion channel TRESK.

BACKGROUND: We investigated the role of tandem pore potassium ion channel (K2P) TRESK in neurobehavioral function and volatile anesthetic sensitivity in genetically modified mice. METHODS: Exon III of the mouse TRESK gene locus was deleted by homologous recombination using a targeting vector. The genotype of bred mice (wild type, knockout, or heterozygote) was determined using polymerase chain reaction. Morphologic and behavioral evaluations of TRESK knockout mice were compared with wild-type littermates. Sensitivity of bred mice to isoflurane, halothane, sevoflurane, and desflurane were studied by determining the minimum alveolar concentration preventing movement to tail clamping in 50% of each genotype. RESULTS: With the exception of decreased number of inactive periods and increased thermal pain sensitivity (20% decrease in latency with hot plate test), TRESK knockout mice had healthy development and behavior. TRESK knockout mice showed a statistically significant 8% increase in isoflurane minimum alveolar concentration compared with wild-type littermates. Sensitivity to other volatile anesthetics was not significantly different. Spontaneous mortality of TRESK knockout mice after initial anesthesia testing was nearly threefold higher than that of wild-type littermates. CONCLUSIONS: TRESK alone is not critical for baseline central nervous system function but may contribute to the action of volatile anesthetics. The inhomogeneous change in anesthetic sensitivity corroborates findings in other K2P knockout mice and supports the theory that the mechanism of volatile anesthetic action involves multiple targets. Although it was not shown in this study, a compensatory effect by other K2P channels may also contribute to these observations.

Regional expression of the anesthetic-activated potassium channel TRESK in the rat nervous system.

The two-pore-domain potassium (K(2P)) channels contribute to background (leak) potassium currents maintaining the resting membrane potential to play an important role in regulating neuronal excitability. As such they may contribute to nociception and the mechanism of action of volatile anesthetics. In the present study, we examined the protein expression pattern of the K(2P) channel TRESK in the rat central nervous system (CNS) and peripheral nervous system (PNS) by immunohistochemistry. The regional distribution expression pattern of TRESK has both similarities and significant differences from that of other K(2P) channels expressed in the CNS. TRESK expression is broadly found in the brain, spinal cord and dorsal root ganglia (DRG). TRESK expression is highest in important CNS structures, such as specific cortical layers, periaqueductal gray (PAG), granule cell layer of the cerebellum, and dorsal horn of the spinal cord. TRESK expression is also high in small and medium sized DRG neurons. These results provide an anatomic basis for identifying functional roles of TRESK in the rat nervous system.

Molecular biology of background K channels: insights from K(2P) knockout mice.

K(2P) channels are a family of cellular proteins that are essential for electrical signaling throughout the body. There are six K(2P) channel subfamilies, consisting of 15 distinct mammalian genes. K(2P) channels display a remarkable range of regulation by cellular, physical and pharmacologic agents, including protein kinases, intracellular Ca(2+), changes in internal and external pH, anesthetic agents, heat, stretch and membrane deformers. The molecular and cellular mechanisms underlying this regulation are complex and cooperate at many different levels. Recent research has provided strong evidence that the spatiotemporal-specific expression of K(2P) channels are determinants of physiologic selectivity and specificity. In recent years, knockout mice have been generated with inactivated K(2P) channel genes. These animals shed new light on the contribution of K(2P) channels to normal and abnormal physiology. In this review, we summarize the published data on these mice to broaden the understanding of the role of K(2P) channel activity.

Gene expression analysis in interstitial lung edema induced by saline infusion.

To investigate the molecular events taking place during the development of hydraulic interstitial edema, we analyzed by microarray and conventional molecular techniques the variation of gene expression in lung from rabbits treated with slow-rate saline infusions. This analysis indicates that even a condition characterized by a small increase in extravascular water can have a significant influence on the inflammatory milieu. In this regard, cytokines, in particular TNFalpha, can be considered early mediators capable of inducing secondary effects on the injured tissue. Moreover, two MT1 genes were strongly up-regulated, data consistent with their role as protective molecules.

Differential regulation of Notch signal transduction in leukaemia and lymphoma cells in culture.

The transduction of Notch signal plays an intricate role in cell differentiation and pathogenesis of haematological malignancies as well as in certain congenital conditions. We found no genomic changes in either gene in 34 leukaemic samples and 25 leukaemia and lymphoma cell lines. The functionality of Notch signalling was tested using HES1 gene activation. We show that Notch signalling is differentially regulated in T-acute lymphoblastic leukaemia (ALL) and B-lymphoma cells. The Notch pathway is intact in a majority of B-lymphoma cell lines, but EBNA2, which mimics notch function, can occasionally activate the pathway. In contrast, the Notch pathway is constitutively active in T-ALL. This is the first demonstration of a distinction between B-lymphomas and T-cell leukaemias in the functioning of the Notch-signalling pathway. This might be related to their pathogenesis.

Allele frequency of two intragenic microsatellite loci of SEL1L gene in Northern Italian population.

Two cytosine-adenine (CA) repeats CAR/CAL and RepIN20 occur in the human SEL1L gene, which is regarded as a candidate gene for insulin-dependent diabetes mellitus (IDDM) and Grave's disease. We have characterized these repeats to determine if they might serve as effective microsatellite markers for linkage analysis to clarify whether SEL1L gene plays a role in the pathogenesis of these autoimmune diseases. The allele frequencies and average heterozygosity of the microsatellite repeats were analysed in 94 DNA samples from peripheral blood mononuclear (PBMC) cells from adults of Northern Italy. The average heterozygosity was 0.68 for CAR/CAL polymorphism and 0.85 for RepIN20. The size of PCR fragments of CAR/CAL ranged from 207-225 bp and the most frequent allele was 207 bp (40.4%). The size of the fragments of RepIN20 ranged from 237-255 bp and the most frequent allele was 249 bp (30.8%). In the light of the highly polymorphic nature of both microsatellites and their intragenic location in SEL1L gene, we suggest that they could provide a means for linkage analysis to clarify the potential role of SEL1L in conferring susceptibility to IDDM or Grave's disease.