Girl with combined cellular immunodeficiency,pancytopenia, malformations,deletion 11q23.3 → qter,and trisomy 8q24.3 → qter

We describe here a 3‐year‐old girl demonstrating combined cellular immunodeficiency of B‐ and T‐cells, pancytopenia, multiple anomalies, and severe mental retardation. Cytogenetic analysis and fluorescent in situ hybridization (FISH) indicated an unbalanced translocation of chromosomes 8q and 11q, resulting in monosomy 11q23.3‐qter and trisomy 8q24.3‐qter. The association of cellular immunodeficiency and partial deletion 11q and/or partial trisomy 8q has not been described previously; however, the 11q deletion has been reported with humoral immunodeficiency or pancytopenia. Some one‐third to one‐half of patients with partial monosomy 11q were reported to have pancytopenia, which has been related to the absence of the 11q23‐q24 region. Our case narrows down the critical interval for thrombo‐ or pancytopenia to 11q23.3‐q24 and excludes both the ATM (which resides on 11q23.1) and the MLL genes as possible candidate genes. We are proposing that haploinsufficiency of the NFRKB gene on 11q24‐q25 and/or the ETS‐1 proto‐oncogene on 11q24 may have caused or contributed to the immunodeficiency (decreased levels of B‐ and T‐lymphocytes) in our patient. © 2002 Wiley‐Liss, Inc.     

1.15 Mb microdeletion in chromosome band 20p13 associated with moderate developmental delay—Additional case and data's review

We report on a 9‐year‐old girl with subtelomeric 20p microdeletion. She was referred for genetic counseling because of learning difficulties/school problems. During the evaluation short stature, hypoplastic fingernails, submucous cleft palate with cleft uvula, flat feet, and frequent upper respiratory infections, as well as the large fontanelle after birth were observed. No facial dysmorphic features specific for chromosomal aberrations were present. The diagnosis of deletion of 20p13 was established by MLPA, and delineated by arrayCGH. Our report describes the third individual with this approximate deletion, and presents detailed molecular and phenotypic characteristics providing new data supporting future genotype–phenotype study. © 2012 Wiley Periodicals, Inc.     

Spitz melanocytic tumours – a review

Spitz tumours comprise a spectrum of melanocytic proliferations that share a set of distinct cytological features and molecular pathways. They include benign naevi, intermediate or indeterminate tumours and rare melanomas. Spitz tumours are notorious for the difficulty of distinguishing benign neoplasms with atypical features from melanomas and the related diagnostic uncertainty. Advances in the knowledge of the molecular pathways and genomic aberrations associated with these neoplasms have permitted opportunities for a reduction in the number of uncertain diagnoses and a more objective distinction between Spitz tumours from Spitz-like neoplasms. The presence of a Spitz molecular pathway, such as Harvey rat sarcoma viral oncogene homologue (HRAS) aberrations or kinase fusions, distinguishes a bona fide Spitz neoplasm from Spitz-like naevi or melanomas with conventional driver mutations. Spitz neoplasms with benign histopathological features and, if such testing is performed, benign cytogenetic and molecular findings, are termed Spitz naevi. Spitz neoplasms with frankly malignant histopathological findings or ambiguous microscopic findings associated with genetic or genomic aberrations most in keeping with melanoma are designated as Spitz melanoma. Tumours with microscopic features and genetic/genomic aberrations in between naevi and melanomas are classified as Spitz melanocytoma.     

Comparative studies of rat IgG to further delineate the Fc : FcRn interaction site

Recent data have indicated that the MHC class I-related receptor, FcRn, regulates the half-lives of serum IgG in addition to its known role in transferring IgG from mother to young. In the current study, the activity of rat IgG (rIgG) isotypes in FcRn-mediated functions has been analyzed. The serum half-life and maternofetal transfer in mice decreased in the order rIgG2a > rIgG1 > rIgG2c > rIgG2b. This decrease in activity correlates well with reduced binding affinity for soluble mouse FcRn, and site-directed mutagenesis of a recombinant Fc-hinge fragment has been used to investigate the molecular basis for the differences in activities of the rIgG. Analysis of the serum half-lives of the mutated Fc-hinge fragments demonstrated that, in addition to Ile253, His310, His435 and His436 that were identified in earlier studies, amino acids at positions 257, 307 and 309 play a role in building the FcRn interaction site of IgG. The study also excludes the involvement of amino acids in a fourth loop located at the CH2-CH3 domain interface that encompasses residues 386 – 387 in FcRn binding. Sequence differences at positions 257, 307 and 309 between rIgG most likely account for the reduced affinity of rIgG2b and IgG2c relative to rIgG1 and rIgG2a for binding to FcRn.     

High‐throughput sequencing of a 4.1 Mb linkage interval reveals FLVCR2 deletions and mutations in lethal cerebral vasculopathy

Rare lethal disease gene identification remains a challenging issue, but it is amenable to new techniques in high‐throughput sequencing (HTS). Cerebral proliferative glomeruloid vasculopathy (PGV), or Fowler syndrome, is a severe autosomal recessive disorder of brain angiogenesis, resulting in abnormally thickened and aberrant perforating vessels leading to hydranencephaly. In three multiplex consanguineous families, genome‐wide SNP analysis identified a locus of 14 Mb on chromosome 14. In addition, 280 consecutive SNPs were identical in two Turkish families unknown to be related, suggesting a founder mutation reducing the interval to 4.1 Mb. To identify the causative gene, we then specifically enriched for this region with sequence capture and performed HTS in a proband of seven families. Due to technical constraints related to the disease, the average coverage was only 7×. Nonetheless, iterative bioinformatic analyses of the sequence data identified mutations and a large deletion in the FLVCR2 gene, encoding a 12 transmembrane domain‐containing putative transporter. A striking absence of alpha‐smooth muscle actin immunostaining in abnormal vessels in fetal PGV brains, suggests a deficit in pericytes, cells essential for capillary stabilization and remodeling during brain angiogenesis. This is the first lethal disease‐causing gene to be identified by comprehensive HTS of an entire linkage interval. Hum Mutat 31:1–8, 2010. © 2010 Wiley‐Liss, Inc.     

DNA immunization in relB-deficient mice discloses a role for dendritic cells in IgM → IgG1 switch in vivo

A single intraspleen inoculation of plasmid DNA coding for an immunoglobulin heavy chain gene initiates immunity and establishes immunologic memory against the antigenic determinants of transgenic immunoglobulins, somatic transgene immunization. During priming mice produce IgM but not IgG1 antibodies. Since IgM → IgG1 class switch occurs spontaneously during the primary immune response to protein antigens we investigated possible mechanisms for failure of spontaneous isotype switch in vivo in this model of immunity. We found that inoculation of plasmid DNA in the form of a chimeric gene coding for granulocyte-macrophage colony-stimulating factor (GM-CSF) was able to drive IgG1 class switch readily after priming. Since GM-CSF activates cells of the dendritic lineage we tested the possibility that dendritic cells (DC) may be involved in regulating IgM → IgG1 switch. To this end we used bone marrow chimeras constructed from mice carrying the null mutation for the relB member of the NF-κB/Rel family as these mice lack bone marrow-derived mature DC. RelB (-/-) mice and (-/-) bone marrow chimeras inoculated with DNA/GM-CSF did not produce IgG1 antibodies during the primary immune response. Since relB (-/-) bone marrow chimeras lack DC of donor origin but possess resident follicular dendritic cells we conclude that Ig class switch in vivo is regulated by the function of interdigitating dendritic cells (IDC). Thus, IDC may contribute to the qualitative aspects of the emerging immune response.     

NMR Study of Hyperbranched Polyphenylenes from the AB2, (AB2 + AB) and (A2 + B3) Methods

Summary: The ¹H NMR and ¹³C NMR spectra of hyperbranched polyphenylenes synthesised from AB₂, (AB₂ + AB) and (A₂ + B₃) monomers (A: ethynyl group; B: cyclopentadienonyl group) were analysed with respect to the characteristic substructures of these polymers. The broad and overlapping NMR spectra were studied by a combination of 1D and 2D NMR techniques. Furthermore, appropriate model compounds were synthesised, and their ¹H and ¹³C NMR spectra were fully assigned. The signal assignments achieved allow to substantiate the different hyperbranched polyphenylene structures. Steric hindrance in densely packed di‐ and trihexaarylphenyl substituted units of the (A₂ + B₃) polyphenylenes results in the decrease of the rotation frequency of phenyl rings in these structures to such an extent that the motion is slow on the ¹H NMR time scale. This can be proved both by EXSY and variable‐temperature experiments. Steric constraints were also deduced for the AB₂ polyphenylenes from signal line shape.

Selected spectra from a VT ¹H NMR experiment on polymer 7b (solvent: C₂D₂Cl₄; *–¹³C satellites of the solvent; signal at 7.3 ppm due to traces of CHCl₃).