Ehlers-Danlos Syndrome Caused by Biallelic TNXB Variants in Patients with Congenital Adrenal Hyperplasia.

Some variants that cause autosomal-recessive congenital adrenal hyperplasia (CAH) also cause hypermobility type Ehlers-Danlos syndrome (EDS) due to the monoallelic presence of a chimera disrupting two flanking genes: CYP21A2, encoding 21-hydroxylase, necessary for cortisol and aldosterone biosynthesis, and TNXB, encoding tenascin-X, an extracellular matrix protein. Two types of CAH tenascin-X (CAH-X) chimeras have been described with a total deletion of CYP21A2 and characteristic TNXB variants. CAH-X CH-1 has a TNXB exon 35 120-bp deletion resulting in haploinsufficiency, and CAH-X CH-2 has a TNXB exon 40 c.12174C>G (p.Cys4058Trp) variant resulting in a dominant-negative effect. We present here three patients with biallelic CAH-X and identify a novel dominant-negative chimera termed CAH-X CH-3. Compared with monoallelic CAH-X, biallelic CAH-X results in a more severe phenotype with skin features characteristic of classical EDS. We present evidence for disrupted tenascin-X function and computational data linking the type of TNXB variant to disease severity.

Broadening the Spectrum of Ehlers Danlos Syndrome in Patients With Congenital Adrenal Hyperplasia.

CONTEXT: The contiguous gene deletion syndrome (CAH-X) was described in a subset (7%) of congenital adrenal hyperplasia (CAH) patients with a TNXA/TNXB chimera, resulting in deletions of CYP21A2, encoding 21-hydroxylase necessary for cortisol biosynthesis, and TNXB, encoding the extracellular matrix glycoprotein tenascin-X (TNX). This TNXA/TNXB chimera is characterized by a 120-bp deletion in exon 35 and results in TNXB haploinsufficiency, disrupted TGF-ß signaling, and an Ehlers Danlos syndrome phenotype. OBJECTIVE: The objective of the study was to determine the genetic status of TNXB and resulting protein defects in CAH patients with a CAH-X phenotype but not the previously described TNXA/TNXB chimera. Design, Settings, Participants, and Intervention: A total of 246 unrelated CAH patients were screened for TNXB defects. Genetic defects were investigated by Southern blotting, multiplex ligation-dependent probe amplification, Sanger, and next-generation sequencing. Dermal fibroblasts and tissue were used for immunoblotting, immunohistochemical, and coimmunoprecipitation experiments. MAIN OUTCOME MEASURES: The genetic and protein status of tenascin-X in phenotypic CAH-X patients was measured. RESULTS: Seven families harbor a novel TNXB missense variant c.12174C>G (p.C4058W) and a clinical phenotype consistent with hypermobility-type Ehlers Danlos syndrome. Fourteen CAH probands carry previously described TNXA/TNXB chimeras, and seven unrelated patients carry the novel TNXB variant, resulting in a CAH-X prevalence of 8.5%. This highly conserved pseudogene-derived variant in the TNX fibrinogen-like domain is predicted to be deleterious and disulfide bonded, results in reduced dermal elastin and fibrillin-1 staining and altered TGF-ß1 binding, and represents a novel TNXA/TNXB chimera. Tenascin-X protein expression was normal in dermal fibroblasts, suggesting a dominant-negative effect. CONCLUSIONS: CAH-X syndrome is commonly found in CAH due to 21-hydroxylase deficiency and may result from various etiological mechanisms.

Recombinant human factor VIIa for alveolar hemorrhage following allogeneic stem cell transplantation.

The mortality rate of alveolar hemorrhage (AH) after allogeneic hematopoietic stem cell transplantation is greater than 60% with supportive care and high-dose steroid therapy. We performed a retrospective cohort analysis to assess the benefits and risks of recombinant human factor VIIa (rFVIIa) as a therapeutic adjunct for AH. Between 2005 and 2012, 57 episodes of AH occurred in 37 patients. Fourteen episodes (in 14 patients) were treated with steroids alone, and 43 episodes (in 23 patients) were treated with steroids and rFVIIa. The median steroid dose was 1.9 mg/kg/d (interquartile range [IQR], 0.8 to 3.5 mg/kg/d; methylprednisolone equivalents) and did not differ statistically between the 2 groups. The median rFVIIa dose was 41 µg/kg (IQR, 39 to 62 µg/kg), and a median of 3 doses (IQR, 2 to 17) was administered per episode. Concurrent infection was diagnosed in 65% of the episodes. Patients had moderately severe hypoxia (median PaO2/FiO2, 193 [IQR, 141 to 262]); 72% required mechanical ventilation, and 42% survived to extubation. The addition of rFVIIa did not alter time to resolution of AH (P = .50), duration of mechanical ventilation (P = .89), duration of oxygen supplementation (P = .55), or hospital mortality (P = .27). Four possible thrombotic events (9% of 43 episodes) occurred with rFVIIa. rFVIIa in combination with corticosteroids did not confer clear clinical advantages compared with corticosteroids alone. In patients with AH following hematopoietic stem cell transplantation, clinical factors (ie, worsening infection, multiple organ failure, or recrudescence of primary disease) may be more important than the benefit of enhanced hemostasis from rFVIIa.

Performance of galanin transgenic mice in the 5-choice serial reaction time attentional task.

The neuropeptide galanin impairs learning and memory in rodents. The mechanism underlying the cognitive effects of galanin may be related to inhibitory effects of galanin on cholinergic transmission. As cholinergic function is thought to modulate sustained attention, the present study examined whether galanin-overexpressing transgenic mice have impairments in sustained attention. Galanin transgenic (GAL-tg) mice and wild-type (WT) littermate controls were trained in a 5-choice serial reaction time task, modified to assess sustained attention. GAL-tg and WT mice performed similarly during acquisition with respect to accuracy, total omissions, and response speed. Attentional mechanisms were challenged by parametric changes including increased event rate, event asynchrony, or decreased stimulus duration. Singly, these challenges did not differentially affect performance between genotypes. Concurrent administration of these challenges, which represents an optimal test of sustained attention, also had similar effects on GAL-tg and WT mice. When stimulus discriminability was reduced by constant illumination of the house light, GAL-tg mice omitted more trials than WT mice, but other measures of performance did not differ by genotype. Moreover, intraventricular injection of galanin in WT mice did not affect sustained attention. These data indicate that previously reported learning and memory effects of galanin are not secondary to attentional dysfunction.

Galanin impairs performance on learning and memory tasks: findings from galanin transgenic and GAL-R1 knockout mice.

Galanin (GAL) impairs performance on cognitive tasks when administered centrally to rats. GAL transgenic (GAL-tg) mice overexpressing endogenous GAL show deficits on the probe trial of the Morris water maze spatial learning task, on the social transmission of food preference olfactory memory task, and on the trace cued fear conditioning emotional learning and memory task. Knockout mice deficient in the GAL-R1 receptor subtype were normal on most memory tasks, while showing a small deficit in trace cued fear conditioning, suggesting a selective role for the GAL-R1 in aversive memories, and implicating other GAL receptor subtypes in spatial learning and olfactory social memory. The growing body of rodent literature implicating excess GAL in cognitive impairment is relevant to the overexpression of GAL in the basal forebrain during the progression of Alzheimer's disease.

Assembly of adherens junctions is required for sphingosine 1-phosphate-induced matriptase accumulation and activation at mammary epithelial cell-cell contacts.

Sphingosine 1-phosphate (S1P), a bioactive phospholipid, simultaneously induces actin cytoskeletal rearrangements and activation of matriptase, a membrane-associated serine protease in human mammary epithelial cells. In this study, we used a monoclonal antibody selective for activated, two-chain matriptase to examine the functional relationship between these two S1P-induced events. Ten minutes after exposure of 184 A1N4 mammary epithelial cells to S1P, matriptase was observed to accumulate at cell-cell contacts. Activated matriptase first began to appear as small spots at cell-cell contacts, and then its deposits elongated along cell-cell contacts. Concomitantly, S1P induced assembly of adherens junctions and subcortical actin belts. Matriptase localization was observed to be coincident with markers of adherens junctions at cell-cell contacts but likely not to be incorporated into the tightly bound adhesion plaque. Disruption of subcortical actin belt formation and prevention of adherens junction assembly led to prevention of accumulation and activation of the protease at cell-cell contacts. These data suggest that S1P-induced accumulation and activation of matriptase depend on the S1P-induced adherens junction assembly. Although MAb M32, directed against one of the low-density lipoprotein receptor class A domains of matriptase, blocked S1P-induced activation of the enzyme, the antibody had no effect on S1P-induced actin cytoskeletal rearrangement. Together, these data indicate that actin cytoskeletal rearrangement is necessary but not sufficient for S1P-induced activation of matriptase at cell-cell contacts. The coupling of matriptase activation to adherens junction assembly and actin cytoskeletal rearrangement may serve to ensure tight control of matriptase activity, restricted to cell-cell junctions of mammary epithelial cells.