Phenotype and genotype in 17 patients with Goltz-Gorlin syndrome.

BACKGROUND: Goltz-Gorlin syndrome or focal dermal hypoplasia is a highly variable, X-linked dominant syndrome with abnormalities of ectodermal and mesodermal origin. In 2007, mutations in the PORCN gene were found to be causative in Goltz-Gorlin syndrome. METHOD: A series of 17 patients with Goltz-Gorlin syndrome is reported on, and their phenotype and genotype are described. RESULTS: In 14 patients (13 females and one male), a PORCN mutation was found. Mutations included nonsense (n = 5), frameshift (n = 2), aberrant splicing (n = 2) and missense (n = 5) mutations. No genotype-phenotype correlation was found. All patients with the classical features of the syndrome had a detectable mutation. In three females with atypical signs, no mutation was found. The male patient had classical features and showed mosaicism for a PORCN nonsense mutation in fibroblasts. Two affected sisters had a mutation not detectable in their parents, supporting germline mosaicism. Their father had undergone radiation for testicular cancer in the past. Two classically affected females had three severely affected female fetuses which all had midline thoracic and abdominal wall defects, resembling the pentalogy of Cantrell and the limb-body wall complex. Thoracic and abdominal wall defects were also present in two surviving patients. PORCN mutations can possibly cause pentalogy of Cantrell and limb-body wall complexes as well. Therefore, particularly in cases with limb defects, it seems useful to search for these. CONCLUSIONS: PORCN mutations can be found in all classically affected cases of Goltz-Gorlin syndrome, including males. Somatic and germline mosaicism occur. There is no evident genotype-phenotype correlation.

Clinical features in a family with an R460H mutation in transforming growth factor beta receptor 2 gene.

OBJECTIVES: To describe the clinical findings and natural history in 22 carriers of an R460H mutation in the transforming growth factor beta receptor 2 gene (TGFbetaR2) from a five-generation kindred ascertained by familial aortic dissection. METHODS: 13 of the confirmed carriers were interviewed and examined, and information about the remaining carrier was obtained from medical records. Clinical information about deceased individuals was obtained, when possible, from postmortem reports, death certificates and medical records. RESULTS: There have been eight sudden deaths; the cause of death was aortic dissection in all six cases in which a postmortem examination was performed. Three individuals had undergone aortic replacement surgery. Dissection had occurred throughout the aorta, and in one case in the absence of aortic root dilatation. Subarachnoid haemorrhage, due to a ruptured berry aneurysm, had occurred in two individuals. Four gene carriers and one deceased family member who were investigated had tortuous cerebral blood vessels. One had tortuous vertebral arteries, two had tortuous carotid arteries and one a tortuous abdominal aorta. Two individuals were found to have a brachiocephalic artery aneurysm and a subclavian artery aneurysm, respectively. CONCLUSIONS: Despite the predisposition to aortic dilatation and dissection, individuals did not frequently manifest the skeletal features of Marfan syndrome, with the exception of joint hypermobility. No one individual had ocular lens dislocation. Striae and herniae were common. There was some overlap with Ehlers-Danlos syndrome type 4, OMIM 130050, with soft translucent skin, which is easily bruised. Other features were arthralgia, migraine and a tendency to fatigue easily, varicose veins and prominent skin striae. This family provides further evidence that mutations in TGFbetaR2 cause a distinct syndrome that needs to be distinguished from Marfan syndrome to direct investigation and management of patients and shows the natural history, spectrum of clinical features and variable penetrance of this newly recognised condition.

CD40-mediated signaling in monocytic cells: up-regulation of tumor necrosis factor receptor-associated factor mRNAs and activation of mitogen-activated protein kinase signaling pathways.

The biochemical pathways involved in CD40 signaling have been extensively studied in B cells and B cell lines, and appear to be primarily initiated by recruitment of the tumor necrosis factor (TNF) receptor-associated factor (TRAF) signaling proteins to the CD40 cytoplasmic domain. Signaling pathways activated through CD40 in monocytes/macrophages have not been characterized as well as in B cells. Using human monocytes and the human monocytic cell line THP1, we examined signal transduction events induced by CD40 engagement with its ligand, CD154. In human monocytes, all TRAF mRNAs were expressed constitutively and CD40 ligation resulted in a strong up-regulation of TRAF1 mRNA. In THP1 cells, CD40 ligation induced expression of TRAF1 and TRAF5 mRNAs. Engagement of CD40 in both monocytes and THP1 cells led to the rapid and transient activation of the extracellular signal-regulated kinases (ERK) 1 and 2, and to low levels of JNK activation. No CD40-dependent activation of p38 mitogen-activated protein kinase (MAPK) was found. In CD154-stimulated monocytes and THP1 cells the upstream ERK1/2 activator, MAPK kinase (MEK) 1/2, and downstream substrate, c-Myc, were activated. By blocking activation of ERK1/2 with a MEK-specific inhibitor, PD98059, CD40-dependent secretion of the pro-inflammatory cytokines, TNF-alpha, IL-6 and IL-8, was demonstrated to be linked to the ERK1/2 pathway. The ERK1/2 pathway did not appear to be involved in up-regulating TRAF1 and TRAF5 mRNAs in THP1 cells. Collectively, these results suggest distinct differences between B cells and monocytic cells in CD40-dependent activation of MAPK pathways.

Multivalent, but not divalent, antigen receptor cross-linkers synergize with CD40 ligand for induction of Ig synthesis and class switching in normal murine B cells. A redefinition of the TI-2 vs T cell-dependent antigen dichotomy.

A number of previous studies have suggested that cross-linkage of the B cell Ag receptor may be critical for induction of humoral immune responses to T cell-dependent (TD) Ags in vivo. Previous work also indicated a critical role, in these responses, for CD40-mediated signaling mediated by binding of the inducible T cell membrane protein, CD40 ligand (CD40L). Data in this manuscript demonstrate that concentrations of bivalent anti-IgD or anti-IgM Ab as high as 30 micrograms/ml induced little if any enhancement of CD40-dependent Ig secretion by resting murine B cells. In contrast, concentrations as low as 3 pg/ml of multivalent, dextran-conjugated, anti-IgD (alpha delta-dex) or anti-IgM (alpha mu-dex) were strongly synergistic with CD40L for induction of B cell proliferation, viable cell outgrowth, Ig isotype switching, and maturation to Ig secretion. As many as 30% of the B cells became membrane IgG1+ after stimulation with CD40L, anti-Ig-dextran, and IL-4 + IL-5, with a concomitant three- to fivefold increase in numbers of viable cells as compared with control cultures. High Ig secretory responses were obtained in response to the combined actions of CD40L and alpha delta-dex or alpha mu-dex, utilizing concentrations of B cell activator that when acting alone induced only modest Ig secretion. Surprisingly, although we previously demonstrated that alpha delta-dex selectively and strongly suppressed IgE production by T cell-activated B cells, it strikingly augmented IgE expression by CD40L-activated B cells. These data suggest 1) a key role for Ag receptor cross-linkage in CD40-dependent induction of humoral immune responses, 2) that to achieve a membrane Ig-dependent enhancing effect in the presence of activated T cells, TD Ags must be displayed to the B cell as a multivalent array of epitopes, 3) that picomolar concentrations of Ag can mediate this effect, and 4) that at least for induction of IgE responses, B cell stimulation via CD40L or via activated T cells may lead to a qualitatively different pathway of activation.

Regulation of CD40 ligand expression and use of recombinant CD40 ligand for studying B cell growth and differentiation.

Helper T cell activation leads to transient expression of a ligand for the B cell surface protein, CD40. CD40 ligand can deliver helper T cell-derived contact signals to B lymphocytes that drive B cell activation and proliferation. Regulation of expression of CD40 ligand is analogous to that of other helper T cell-derived lymphokines. A soluble form of CD40 ligand is capable of delivering proliferative signals to B cells only when cross-linked or when IL-4 is added. Recombinant CD40 ligand in membrane vesicles can be used to develop in vitro systems for studying class switching, clonal selection, and affinity maturation in normal B lymphocytes.

B cell differentiation induced by helper T cell membranes: evidence for sequential isotype switching and a requirement for lymphokines during proliferation.

Small dense B cells are stimulated to proliferate by membranes prepared from activated helper T (Th) cell clones. In combination with Th2 lymphokines, Th membranes stimulate B cells to differentiate to secrete predominantly immunoglobulin (Ig)M, IgG1 and IgE. The activity in Th membrane requires the expression of CD40 ligand by the T cells, and initiation of the B cell response occurs through the ligation of CD40 on the B cell surface. We have further characterized the properties of the B cell response and found that Th membranes stimulated B cell proliferation and Ig secretion in a cell density independent manner and the majority of the stimulated B cells underwent a limited number of division rounds between day 2 and 5 of culture. IgM-secreting cells appeared in culture by day 3 and increased to reach a maximum, comprised of 30% of the viable cells, on day 5. IgG1-secreting cells appeared 12-24 h after IgM-secreting cells, and IgE-secreting cells did not appear until day 5. These data are consistent with a sequential model of isotype switching related to cell division. As lymphokines were absolutely required for antibody production we were able to determine when during culture they were essential. Lymphokines needed to be present prior to and during B cell proliferation for differentiation to Ig-secreting cells to proceed. This period corresponded closely to the time of maximum DNA synthesis. Consistent with sequential switching of Ig isotypes, differentiation to IgM secretion required the shortest exposure to lymphokines and IgE the longest. These experiments strongly suggest that the lymphokine-induced commitment to differentiate is made before DNA synthesis begins, although the lymphokine-delivered signals are necessary during DNA synthesis to support Ig class switching.

Regulation of expression of the ligand for CD40 on T helper lymphocytes.

Activated Th cells deliver contact-dependent signals to resting B lymphocytes that initiate and drive B cell proliferation. Recently, a ligand for the B lymphocyte membrane protein, CD40, has been identified that delivers contact-dependent Th cell signals to B cells. A dimeric soluble form of CD40 was produced and used to further characterize the regulation of expression of the CD40 ligand. Expression of the CD40 ligand was rapidly induced after Th lymphocyte activation, and its stability depended upon whether Th cells were activated with soluble or plastic-bound stimuli. Th cells activated with soluble stimuli rapidly turned over cell-surface CD40 ligand whereas Th cells activated with plastic-bound stimuli exhibited more stable CD40 ligand expression for up to 48 h. Removal of activated Th cells from the plastic-bound stimulus resulted in a rapid turnover of CD40 ligand, suggesting that continuous stimulation could maintain CD40 ligand expression. Ligation by soluble CD40 could also stabilize expression of CD40 ligand on the Th cell surface. Both CD40 ligand and IL-2 were transiently synthesized from 1 to 12 h after Th cell activation and had similar kinetics of synthesis. In Con A-activated Th cells newly synthesized CD40 ligand exhibited an initial high turnover (1.5 h t1/2) and after 5 h of Th cell activation became more stable (10-h t1/2). In Th cells activated with plastic-bound anti-CD3, CD40 ligand exhibited a similar biphasic turnover except that the rapid turnover phase began significantly later. This delay could allow more time for newly synthesized CD40 ligand to assemble or associate with other molecules and thus become stabilized on the cell surface. Newly synthesized CD40 ligand in Con A-activated Th cells appeared to not be efficient in delivering Th cell-dependent contact signals to resting B cells, implying the need for assembly or accessory proteins. Regulation of CD40 ligand expression was consistent with all the characteristics of Th cell-delivered contact signals to B cells and may contribute to the high degree of specificity in B cell responses.

Purification of a 130-kDa T cell glycoprotein that binds human interleukin 4 with high affinity.

The interleukin 4 (IL-4) receptor was purified from the gibbon T cell line MLA 144. These cells were found to express high numbers of human IL-4-binding proteins (5000-6000 sites/cell) with an affinity constant (Kd) similar to that measured in human cell lines (Kd = 40-70 pM). Affinity cross-linking of 125I-IL-4 to human cell lines and MLA 144 cells demonstrated the labeling of three proteins of approximately 130, 75, and 65 kDa. Human IL-4-binding sites were solubilized from MLA 144 cells using Triton X-100 and then purified by carboxymethyl chromatography, which removed 50% of the protein without loss of IL-4-binding activity. Then sequential affinity purification over wheat germ agglutinin and a single IL-4 Affi-Gel 10 column resulted in a final 8000-fold purification of the IL-4 receptor. When analyzed on a silver-stained sodium dodecyl sulfate-polyacrylamide gel, the purified receptor migrated as a single molecular species of 130 +/- 5 kDa. Identification of the 130-kDa protein as the IL-4 receptor was demonstrated by cross-linking experiments and specific binding of 125I-IL-4 to nitrocellulose membranes after electrophoretic transfer of the purified receptor on sodium dodecyl sulfate-polyacrylamide gel.

Expression of high affinity receptors for murine interleukin 4 (BSF-1) on hemopoietic and nonhemopoietic cells.

In this report a method for the affinity purification and radiolabeling of recombinant mouse interleukin (IL)-4 is described. It is shown on the basis of several criteria that IL-4 retains full biologic activity after radioiodination and can therefore be used as a valid model for measuring the binding characteristics of native IL-4. By using Scatchard plot analysis of equilibrium binding data, it is demonstrated that 125I-IL-4 binds to a high affinity cell surface receptor which is expressed by both hemopoietic and nonhemopoietic cells. The dissociation constant for 125I-IL-4 (Kd = 20 to 60 pM) corresponds to the concentration of IL-4 which gives 50% biologic activity (i.e., 10 to 30 pM). Binding of 125I-IL-4 is rapid (t1/2 of 2 min), whereas dissociation occurs at a slow rate (t1/2 approximately 4 hr). The IL-4 receptor shows a high degree of specificity. Whereas unlabeled mouse IL-4 competed with mouse 125I-IL-4 in an equimolar fashion for binding to IL-4 receptors, several other lymphokines, including mouse IL-2, IL-3, interferon-gamma, granulocyte-macrophage colony-stimulating factor, and human IL-1, IL-2, and IL-4 were unable to inhibit, even at molar excesses of 400 to 800-fold. At 37 degrees C, 125I-IL-4 is rapidly internalized (approximately 200 molecules/cell/min) by HT-2 cells, with at least 85% of cell surface receptors being functional in this respect. Receptors for IL-4 were found to be expressed by subclasses of T and B cells, mast cells, macrophages, and by cells of the myeloid and erythroid lineages. This wide distribution of receptor expression closely matches the known spectrum of biologic activities of IL-4, including proliferation and/or differentiation of T and B cells, mast cells and granulocytes, and induction of macrophage antigen-presenting capacity. IL-4 receptors were also found on a variety of nonhemopoietic cells such as cloned stromal cell lines from the bone marrow, spleen, thymus, and brain, and on muscle, brain, melanoma, fibroblast, and liver cells. Indeed, only 5 of more than 90 cell types tested have undetectable numbers of IL-4 receptors. The biologic effects of IL-4 on nonhemopoietic cells have not yet been reported and await elucidation.

In-utero intravascular transfusion of the fetus for the management of severe Rhesus isoimmunization--a reappraisal.

Ten fetuses, severely affected by Rhesus (D) haemolytic disease, received one to three intravascular blood transfusions at between 18 and 30 weeks gestation, with the use of fetoscopically guided needles into one of the umbilical cord vessels. Although the technique was successfully accomplished in all cases, the fetal response to the procedure was varied. Only two fetuses survived beyond the neonatal period, and one child subsequently died principally because of the problems resulting from premature delivery. The reason for the low rate of survival has been explored and the continued use of the method described is now questioned.

The obstetric management of non-immunological hydrops.

During the past 8 years, non-Rhesus hydrops has been observed in 31 pregnancies extending beyond 28 weeks gestation. Only three of the babies survived. Antenatal diagnosis is possible by ultrasound examination and although 27 of our patients had at least one indication for this procedure, only 22 were so investigated and in 13, fetal hydrops was demonstrated. Twenty-three were delivered before 36 weeks gestation, 10 by caesarean section of whom none survived; 16 babies were stillborn. Fourteen infants had major cardiovascular anomalies and six had other major malformations. In five infants, infection was thought to be causally related to fetal hydrops and in only four could no cause for the hydrops be found. In five pregnancies the cause of hydrops was discovered antenatally; this influenced subsequent management and two of the five survived. The unexpected appearance of a very abnormal fetal heart rate pattern requires the exclusion of fetal anomaly and non-immunological hydrops. When a diagnosis of non-immune hydrops is made its underlying cause should be sought without delay so that specific treatment may be instituted in the few cases where this is appropriate. A high incidence of complications of the third stage of labour should be anticipated. Subsequent pregnancies are likely to be normal.