Detection of heterozygous SALL1 deletions by quantitative real time PCR proves the contribution of a SALL1 dosage effect in the pathogenesis of Townes-Brocks syndrome

Townes-Brocks syndrome (TBS) is an autosomal dominantly inherited disorder characterized by ear, anal, limb, and renal malformations, and results from mutations in the gene SALL1. All SALL1 mutations previously found in TBS patients create preterminal termination codons. In accordance with the findings of pericentric inversions or balanced translocations, TBS was initially assumed to be caused by SALL1 haploinsufficiency. This assumption was strongly contradicted by a Sall1 mouse knock-out, because neither hetero- nor homozygous knock-out mutants displayed a TBS-like phenotype. A different mouse mutant mimicking the human SALL1 mutations, however, showed a TBS-like phenotype in the heterozygous situation, suggesting a dominant-negative action of the mutations causing TBS. We applied quantitative real time PCR to detect and map SALL1 deletions in 240 patients with the clinical diagnosis of TBS, who were negative for SALL1 mutations. Deletions were found in three families. In the first family, a 75 kb deletion including all SALL1 exons had been inherited by two siblings from their father. A second, sporadic patient carried a de novo 1.9-2.6 Mb deletion including the whole SALL1 gene, and yet another sporadic case was found to carry an intragenic deletion of 3384 bp. In all affected persons, the TBS phenotype is rather mild as compared to the phenotype resulting from point mutations. These results confirm that SALL1 haploinsufficiency is sufficient to cause a mild TBS phenotype but suggest that it is not sufficient to cause the severe, classical form. It therefore seems that there is a different contribution of SALL1 gene function to mouse and human embryonic development.     

Vitamin D deficiency in children with recurrent respiratory infections,with or without immunoglobulin deficiency

Purpose

The objective of this study was to evaluate thevitamin D concentration in patients with recurrent respiratory infections with or without immunoglobulin G, A or M (IgG, IgA, IgM) deficiency, and to find a correlation between the vitamin D concentration and the response to hepatitis B vaccination.

Delayed diagnosis of adrenal hypoplasia congenita in a patient with a new mutation in the NR0B1 gene

Determining the precise cause of adrenal insufficiency occurring in infancy is of critical importance for both the correct management of affected children and the provision of correct genetic advice to their families. We report a case of a 24-year-old, male patient bearing a new mutation in the DAX1 gene. The patient was born at term, from a healthy pregnancy. Adrenal insufficiency was diagnosed in the fourth week of life with a salt-wasting syndrome, but it was mistakenly believed to be secondary to congenital adrenal hyperplasia (CAH). On hydrocortisone substitution, the child continued to develop normally, but the diagnosis of CAH was questioned, which led to an episode of an abrupt withdrawal of hydrocortisone substitution and subsequently caused a reoccurrence of a life-threatening salt-wasting syndrome. Owing to close follow-up, the patient's gonadal axis deficiency was promptly identified, which allowed an assisted but successful onset of puberty. We proposed the diagnosis of adrenal hypoplasia congenita (AHC) in this patient and identified a hemizygous mutation (c.1130delAinsGT, p.E377GfsX12) in exon 1 of the NR0B1 gene. To our knowledge, the detected mutation has not been described previously (HGMD Professional 2010.4, Human Gene Mutation Database, Biobase, Beverly, MA, USA). It leads to a frameshift, a premature stop codon, and, most likely, non-sense-mediated decay of the mutant mRNA. In this case, close patient follow-up minimized the detrimental consequences of an incorrect diagnosis. Nevertheless, it highlights the importance of the early precise diagnosis of patients with AHC.     

Monosomy 21 in hematologic diseases

Monosomy 21 mosaicism as a sole cytogenetic abnormality is very uncommon, with 47 cases described in the literature. We identified five cases of low-level monosomy 21 mosaicism since 1998, none of which were confirmed by fluorescence in situ hybridization (FISH) analysis or follow-up cytogenetic studies. These five cases, and many of the previously reported cases, probably represent the random appearance of several monosomy 21 cells as artifacts of cell culture or microscope slide preparation. The most convincing reported cases of monosomy 21 mosaicism suggest a rare association of monosomy 21 with acute myelocytic leukemia and chronic lymphocytic leukemia. Future cases suggestive of monosomy 21 mosaicism should be confirmed by analysis of additional metaphase cells and by FISH analysis of interphase cells.     

Detection of β-Herpesviruses in Polish Adult Cord Blood Stem Cell Recipients by Real-Time PCR: Single Centre Study

Umbilical cord blood transplantation (UCBT) is known to be associated with increased risk of infections, compared to bone marrow or peripheral blood stem cell transplantation. In viral diseases for which specific treatment is available, real-time PCR assays are reliable diagnostic tools for timely initiation of appropriate therapy and for rapid assessment of the efficacy of antiviral treatment strategies. A retrospective review of samples from a group of seven adult cord blood stem cell recipients was made. Serum samples taken up to 180 days after transplantation were examined with quantitative real-time PCR for measurement of viral load (CMV, HHV-6, and HHV-7). Cytomegalovirus (CMV) DNA was detected in samples taken from four patients (57%) in the period of 20–80 days after transplantation. Products of amplification of human herpesvirus 6 (HHV-6) DNA were found in samples taken between days 25 and 37 following UCBT from only one patient (14%). On the other hand, the majority of patients (n = 6, 86%) had HHV-7 DNA detected in the period 15–58 days after transplantation. Co-infection with HHV-7 was demonstrated at onset of all episodes of microbiologically confirmed CMV or HHV-6 infection. Our observations indicate that real-time PCR is not only useful for monitoring herpesviral infections in transplant recipients, but is also a powerful method for clarifying the relationships between the viral load and clinical symptoms. Further investigation with a much larger group of patients will be needed to confirm these observations and translate them into a clinical approach.     

Silencing preBötzinger complex somatostatin-expressing neurons induces persistent apnea in awake rat

Delineating neurons that underlie complex behaviors is of fundamental interest. Using adeno-associated virus 2, we expressed the Drosophila allatostatin receptor in somatostatin (Sst)-expressing neurons in the preB?tzinger Complex (preB?tC). Rapid silencing of these neurons in awake rats induced a persistent apnea without any respiratory movements to rescue their breathing. We hypothesize that breathing requires preB?tC Sst neurons and that their sudden depression can lead to serious, even fatal, respiratory failure.     

Human T cell lymphotropic virus type I (HTLV-I) among female prostitutes in Kinshasa, Zaire

Three hundred seventy-seven prostitutes from Kinshasa, Zaire, were enrolled in a study to determine associated risk factors for human immunodeficiency virus type 1 (HIV-1) and human T cell lymphotropic virus type I (HTLV-I) infection. Twelve samples (3.2%) were seropositive for HTLV-I; results for HIV-1 (101 [26.8%]) are reported elsewhere. HTLV-I prevalence increased with age, and seven of the seropositive women originated from the Equateur region, a remote area in northwestern Zaire. The prevalence among women from Equateur (7.2%) was higher than that of women from all other regions (1.8%, P = .02). Presence of HTLV-I antibodies was not associated with frequency or type of sex practice. In a subsequent study, 350 serum samples were obtained from a variety of subjects in the Equateur region in 1986. Nineteen (5.4%) showed antibodies to HTLV-I. These data and a recent report of a cluster of patients with tropical spastic paraparesis from this region suggest that HTLV-I is endemic in the Equateur region of Zaire.     

Characterization of a de novo 48,XX, + r(X), + r(17) by in situ hybridizatio in a patient with neurofibromatosis (NF1)

We describe a patient with familial neurofibromatosis (NF1), short stature, developmental delay, and a de novo chromosome abnormality. In sity hybridization was done using chromosome specific centromere probes to characterize the karyotype as 46,XX/47, XX,+r(X) (p11q11)/47,XX,+r(17) (p11q11)/48, XX,+r(X) (p11q11),+r(17) (p11q11). The NF1 mutation, as well as each superunmerary ring chromosome, may have played a role in perturbing the normal developmenal process of this patient. © 1993 Wiley-Liss, Inc.     

Dynamic structure of lipid-bound synaptobrevin suggests a nucleation-propagation mechanism for trans-SNARE complex formation

The synaptic vesicle protein synaptobrevin engages with syntaxin and SNAP-25 to form the SNARE complex, which drives membrane fusion in neuronal exocytosis. In the SNARE complex, the SNARE motif of synaptobrevin forms a 55-residue helix, but it has been assumed to be mostly unstructured in its prefusion form. NMR data for full-length synaptobrevin in dodecylphosphocholine micelles reveals two transient helical segments flanked by natively disordered regions and a third more stable helix. Transient helix I comprises the most N-terminal part of the SNARE motif, transient helix II extends the SNARE motif into the juxtamembrane region, and the more stable helix III is the transmembrane domain. These helices may have important consequences for SNARE complex folding and fusion: helix I likely forms a nucleation site, the C-terminal disordered SNARE motif may act as a folding arrest signal, and helix II likely couples SNARE complex folding and fusion.     

压电频移中和萃取法测定微克量枸橼酸维静宁

用涂圈压电石英晶体频移一中和萃取法测定枸橼酸维静宁(咳必清),检出限0.02μg,在0.05～1.6μg范围内呈线性,相关系数0.999,变异系数为2.3%。与经典的中和萃取法相比,本法具有明显的优越性。