Genotype�Cphenotype correlations in Down syndrome identified by array CGH in 30 cases of partial trisomy and partial monosomy chromosome 21

Down syndrome (DS) is one of the most frequent congenital birth defects, and the most common genetic cause of mental retardation. In most cases, DS results from the presence of an extra copy of chromosome 21. DS has a complex phenotype, and a major goal of DS research is to identify genotype–phenotype correlations. Cases of partial trisomy 21 and other HSA21 rearrangements associated with DS features could identify genomic regions associated with specific phenotypes. We have developed a BAC array spanning HSA21q and used array comparative genome hybridization (aCGH) to enable high-resolution mapping of pathogenic partial aneuploidies and unbalanced translocations involving HSA21. We report the identification and mapping of 30 pathogenic chromosomal aberrations of HSA21 consisting of 19 partial trisomies and 11 partial monosomies for different segments of HSA21. The breakpoints have been mapped to within ∼85 kb. The majority of the breakpoints (26 of 30) for the partial aneuploidies map within a 10-Mb region. Our data argue against a single DS critical region. We identify susceptibility regions for 25 phenotypes for DS and 27 regions for monosomy 21. However, most of these regions are still broad, and more cases are needed to narrow down the phenotypic maps to a reasonable number of candidate genomic elements per phenotype.     

Maternally inherited partial monosomy 9p (pter → p24.1) and partial trisomy 20p (pter → p12.1) characterized by microarray comparative genomic hybridization

We report on a 17-year-old patient with midline defects, ocular hypertelorism, neuropsychomotor development delay, neonatal macrosomy, and dental anomalies. DNA copy number investigations using a Whole Genome TilePath array consisting, of 30K BAC/PAC clones showed a 6.36 Mb deletion in the 9p24.1-p24.3 region and a 14.83 Mb duplication in the 20p12.1-p13 region, which derived from a maternal balanced t(9;20)(p24.1;p12.1) as shown by FISH studies. Monosomy 9p is a well-delineated chromosomal syndrome with characteristic clinical features, while chromosome 20p duplication is a rare genetic condition. Only a handful of cases of monosomy 9/trisomy 20 have been previously described. In this report, we compare the phenotype of our patient with those already reported in the literature, and discuss the role of DMRT, DOCK8, FOXD4, VLDLR, RSPO4, AVP, RASSF2, PROKR2, BMP2, MKKS, and JAG1, all genes mapping to the deleted and duplicated regions.     

A 10 Mb duplication in chromosome band 5q31.3-5q33.1 associated with late-onset lipodystrophy, ichthyosis, epilepsy and glomerulonephritis

We report here a 44 years-old patient with late-onset partial lipodystrophy, mental retardation, epilepsy, ichtyosis and glomerulonephritis, carrying a 10 Mb duplication of the chromosome 5q31.3-5q32.1 region detected by array-CGH.     

Deletion (1)(p32.2-p32.3) detected by array-CGH in a patient with developmental delay/mental retardation, dysmorphic features and low cholesterol: A new microdeletion syndrome?

We report on a 25-year-old male with mental retardation and global developmental delay, low levels of total and LDL cholesterol and dysmorphism, which includes macrocephaly, hypertelorism, synophrys, telecanthus, prominent philtrum, low set ears, bilateral cataracts, bilateral cleft lip with cleft palate and widely spaced nipples. While his karyotype and subtelomeric FISH studies were normal, a de novo, 5.4 Mb interstitial deletion at 1p32 [del(1)(p32.2-p32.3)] was identified by oligonucleotide aCGH. The deleted region encompasses a cluster of genes involved in fatty acid oxidation and cholesterol metabolism. One of these genes is PCSK9, a key regulator for a number of cell-surface LDL receptors. In addition to the loss of the paternal allele, our patient is hemizygous for the A443T weak loss-of-function mutation in exon 8 of PCSK9. Loss-of-function mutations within PCSK9 have been shown to cause hypocholesterolemia. Another gene also mapped to this region and deleted in this patient is DAB1, reported to be involved in brain development. Based on the findings in the current patient and in the four previously reported individuals with del(1)(p32.2-p32.3), we suggest that these patients may have a new microdeletion syndrome that may have gone undetected because of its location in a G-negative band. However, the condition can easily be identified by array-CGH.     

An 8.9?Mb 19p13 duplication associated with precocious puberty and a sporadic 3.9?Mb 2q23.3q24.1 deletion containing NR4A2 in mentally retarded members of a family with an intrachromosomal 19p-into-19q between-arm insertion

In a 2 and a half-year-old girl with onset of puberty before the age of 5 months, short stature, hand anomalies and severe mental retardation, an 8.9 Mb interstitial 19p13 duplication containing 215 predicted genes was detected. It was initially assumed that the duplication involved the kisspeptin receptor gene, GPR54, known to stimulate induction of puberty, but more refined duplication mapping excluded this possibility. In an attempt to further understand the genotype–phenotype correlation, global gene expression was measured in skin fibroblasts. The overall expression pattern was quite similar to controls, and only about 25% of the duplicated genes had an expression level that was increased by more than 1.3-fold, with no obvious changes that could explain the precocious puberty. The proband''s mother carried a balanced between-arm insertion of the duplicated segment that resembled a pericentric inversion. The same insertion was found in several other family members, including one who had lost a daughter with severe mental retardation and menarche at the age of 10 years. Another close relative was severely mentally retarded, but neither dysmorphic nor microcephalic. His phenotype was initially ascribed to a presumed cryptic chromosome 19 imbalance caused by the 19p-into19q insertion, but subsequent array-CGH detected a 3.9-Mb deletion of 2q23.3q24.1. This novel microdeletion involves seven genes, of which FMNL2, a suggested regulator of Rho-GTPases, and NR4A2, an essential gene for differentiation of dopaminergic neurons, may be critical genes for the proposed 2q23q24 microdeletion syndrome.     

Robust interferon-α and IL-12 responses by dendritic cells are related to efficient CD4+ T-cell recovery in HIV patients on ART

Amongst HIV patients with successful virological responses to antiretroviral therapy (ART), poor CD4(+) T-cell recovery is associated with low nadir CD4(+) T-cell counts and persistent immune activation. These factors might be influenced by dendritic cell (DC) function. Interferon-α-producing plasmacytoid DC and IL-12-producing myeloid DC were quantified by flow cytometry after stimulation with agonists to TLR7/8 (CL075) or TLR9 (CpG-ODN). These were compared between patients who achieved CD4(+) T-cell counts above or below 200 cells/μL after 6 months on ART (High vs. Low groups). High Group patients had more DC producing interferon-α or IL-12 at Weeks 6 and 12 on ART than Low Group patients. The frequencies of cytokine-producing DC at Week 12 were directly correlated with CD4(+) T-cell counts at baseline and at Week 12. Patients with good recovery of CD4(+) T-cells had robust TLR-mediated interferon-α responses by plasmacytoid DC and IL-12 responses by myeloid DC during early ART (1-3 months).     

TGF-β promotes proliferation of thyroid epithelial cells in IFN-γ(-/-) mice by down-regulation of p21 and p27 via AKT pathway

IFN-γ(-/-) NOD.H-2h4 mice develop an autoimmune disease characterized by hyperplasia and proliferation of thyroid epithelial cells (TEC H/P). Proliferating TECs produce TGF-β, and IFN-γ inhibits TEC H/P. In the present study, cultured TECs were used to directly determine the mechanisms by which these cytokines act on TECs to result in proliferation or inhibition of proliferation. With TECs from IFN-γ(-/-) NOD.H-2h4 mice or mice expressing the dominant negative TGF-β type II receptor on TECs, TGF-β was shown to promote TEC proliferation and IFN-γ was shown to inhibit TEC proliferation in vitro. TGF-β may promote TEC proliferation by down-regulating antiproliferative molecules p21 and p27, whereas IFN-γ may inhibit proliferation by up-regulating antiproliferative molecules p18 and p21 and down-regulating the pro-proliferative molecule cyclin D. Inhibition of AKT abolished the effect of TGF-β on p21 and p27, resulting in similar proliferation of TGF-β-treated and control TECs. Increased expression of proliferating cell nuclear antigen (PCNA), TGF-β, and p-AKT and decreased expression of p21 and p27 by proliferating TECs correlated with the proliferative state of TEC H/P. Taken together, the results suggest that TGF-β promotes TEC proliferation by down-regulating p21 and p27 via the AKT pathway in IFN-γ(-/-) NOD.H-2h4 mice, which may have significant implications for development of effective therapeutic strategies targeting the TGF-β and AKT pathways for treatment of hyperplasia and/or neoplasia.     

Platelet activation and red blood cell phosphatidylserine exposure evaluated by flow cytometry in patients with Behçet's disease: are they related to thrombotic events?

Beh?et's disease (BD) is associated with an increased risk of venous and arterial thromboses that are associated with morbidity and mortality increase, although the mechanisms are not well established. In the present study, we used whole blood cytometry to determine the exposure of CD62 on the surface of platelets and the expression of phosphatidylserine (PS) on the surface of circulating red blood cells. Microparticle and microaggregate formation from platelets were also determined in a well-classified group of 72 patients (39 males, 33 females, aged 46.5 +/- 12.5 years) with BD, in comparison with a well-matched control group of 72 healthy volunteers. Results showed no differences in the above-mentioned parameters when BD patients and controls were compared. However, when we compared BD patients with/without thrombosis using these parameters, there were significant differences between both groups. BD patients with previous thrombosis had a higher percentage of circulating CD62-positive platelets and a higher number of circulating microaggregates than those without thrombosis, suggesting that platelet activation may be involved in the development of thrombotic events in these patients.     

GTS-21, an α7nAChR agonist,suppressed the production of key inflammatory mediators by PBMCs that are elevated in COPD patients and associated with impaired lung function

Chronic obstructive pulmonary disease (COPD) is a lung inflammatory disease characterized by progressive airflow limitation, chronic respiratory symptoms and frequent exacerbations. There is an unmet need to identify novel therapeutic alternatives beside bronchodilators that prevent disease progression. Levels of both Nitric Oxide (NO) and IL-6 were significantly increased in the plasma of patients in the exacerbation phase (ECOPD, n = 13) when compared to patients in the stable phase (SCOPD, n = 38). Levels of both NO and IL-6 were also found to inversely correlate with impaired lung function (%FEV1 predicted). In addition, there was a strong positive correlation between levels of IL-6 and NO found in the plasma of patients and those spontaneously produced by their peripheral blood mononuclear cells (PBMCs), identifying these cells as a major source of these key inflammatory mediators in COPD. GTS-21, an agonist for the alpha 7 nicotinic receptors (α7nAChR), was found to exert immune-modulatory actions in PBMCs of COPD patients by suppressing the production of IL-6 and NO. This study provides the first evidence supporting the therapeutic potential of α7nAChR agonists in COPD due to their ability to suppress the production of key inflammatory markers associated with disease severity.     

Familial ring (18) mosaicism in a 23-year-old young adult with 46,XY,r(18) (::p11→q21::)/46,XY karyotype, intellectual disability, motor retardation and single maxillary incisor and in his phenotypically normal mother, karyotype 47,XX,+r(18)(::p11→q21::)/46,XX

We report on a 23-year-old man with craniofacial findings of the holoprosencephaly spectrum disorder (microcephaly, hypotelorism, depressed nasal bridge, single median maxillary central incisor), fusion of C2-C3 vertebrae, intellectual disability, and severe sleep apnea. Chromosome analysis of blood lymphocytes showed 75% ring (18) cells and 25% normal cells, karyotype mos 46,XY,r(18)(::p11→q21::)[75]/46,XY[25]. His mother was phenotypically normal except for a double ureter and bifid renal pelvis as in his son. She had a supernumerary ring (18) in 10% of blood lymphocytes, karyotype mos 47,XX,+r(18)(::p11→q21::)[10]/46,XX[90]. Familial ring (18) is a rare cytogenetic abnormality. This is the first report of a mother with a supernumerary ring (18) and a son with ring (18) mosaicism. Interestingly, the son showed a true mosaicism (mixoploidy) of ring (18) and normal cells. The mother's 46,XX cells could be easily explained by mitotic instability and ring loss during cell division. However, the coexistence of ring (18) and normal cells in the son is unusual. Possibly, during early postzygotic divisions of a 47,XY,+r(18) zygote, two (possibly subsequent) genetic events could have occurred, one when one normal chromosome 18 was lost (resulting in a cell line with ring 18), and one when the ring 18 was lost (resulting in a cell line without ring, "escape to normal"). Alternatively, the zygote of the son could have been 46,XY,r(18), and postzygotic loss of the ring 18 could have resulted in monosomy 18 cells followed by duplication of chromosome 18 in these cells (a rare mechanism for cell survival previously described as "compensatory" isodisomy).     

Cryptic and partial deletions of PRDM16 and RUNX1 without t(1;21)(p36;q22) and/or RUNX1–PRDM16 fusion in a case of progressive chronic myeloid leukemia: A complex chromosomal rearrangement of underestimated frequency in disease progression?

Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by the presence in leukemic stem cells of the Philadelphia chromosome (Ph) and the formation of the BCR-ABL1 fusion. Untreated, the disease progresses to accelerate phase and blast crisis in which hematopoietic differentiation has become arrested. CML progression is frequently associated with cytogenetic evidence of clonal evolution, defined as additional chromosomal aberrations. We here report a CML resistant to tyrosine kinase inhibitors that rapidly progressed to blastic phase. At this time, array CGH performed on CD34(+) cells revealed cryptic partial deletions of both PRDM16 and RUNX1 and duplication of the der(21) chromosome. These genomic rearrangements were confirmed by FISH with probes targeting the deletion on chromosome 21 (24 kb), and with BAC probes flanking the deletion on 1p36 (220 kb). However, no cryptic t(1;21)(p36;q22) and/or RUNX1-PRDM16 were detected, suggesting that these deletions are the residual hallmarks of a more complex mechanism of chromosomal rearrangement, as indicated by the additional inversion of the region bounded by 1p36.32 and 1p36.12 breaks. At the molecular level, these abnormalities lead to the overexpression of the PR-domain negative oncogenic isoform of PRDM16, associated with two deleted copies within the runt domain of C-teminal aberrant RUNX1. These events are not detectable by conventional cytogenetic and molecular strategies, and may be of underestimated frequency in disease progression.