GATA6 mutations: Characterization of two novel patients and a comprehensive overview of the GATA6 genotypic and phenotypic spectrum

The first human mutations in GATA6 were described in a cohort of patients with persistent truncus arteriosus, and the phenotypic spectrum has expanded since then. This study underscores the broad phenotypic spectrum by presenting two patients with de novo GATA6 mutations, both exhibiting complex cardiac defects, pancreatic, and other abnormalities. Furthermore, we provided a detailed overview of all published human genetic variation in/near GATA6 published to date and the associated phenotypes (n = 78). We conclude that the most common phenotypes associated with a mutation in GATA6 were structural cardiac and pancreatic abnormalities, with a penetrance of 87 and 60%, respectively. Other common malformations were gallbladder agenesis, congenital diaphragmatic hernia, and neurocognitive abnormalities, mostly developmental delay. Fifty‐eight percent of the mutations were de novo, and these patients more often had an anomaly of intracardiac connections, an anomaly of the great arteries, and hypothyroidism, compared with those with inherited mutations. Functional studies mostly support loss‐of‐function as the pathophysiological mechanism. In conclusion, GATA6 mutations give a wide range of phenotypic defects, most frequently malformations of the heart and pancreas. This highlights the importance of detailed clinical evaluation of identified carriers to evaluate their full phenotypic spectrum.     

Behavioral and hormonal responses to stress in the newborn mouse: Effects of maternal deprivation and chlordiazepoxide

These studies investigated behavioral and hormonal responses to stress in developing mice. Experiment 1 examined the effects of 24-hr maternal deprivation on corticosterone (CORT) secretion and ultrasonic vocalization (UVZ) rate in 4-, 8-, and 12-day-old mice. At these ages, exposure to a novel environment resulted in minimal changes in CORT secretion. Maternal deprivation increased pups′ CORT secretion in an age-dependent fashion but did not affect their UVZ rate. The aim of experiment 2 was to test the effects of cholordiazepoxide (CDP), an anxyolytic compound, on CORT secretion and UVZ in both normally reared and in maternally deprived 8-day-old mice. CDP administration elevated CORT increases in deprived (DEP) animals. CDP affected UVZ only in nondcprived (NDEP) animals: UVZ ratewas decreased by high CDP doses Overall, these findings demonstrate that the infant mouse shows a period of stress hyp9oresponsiveness similar to the rat and that maternal presence contributes to inhibit adrenocorticalactivity. CDP administration, butnot novelty exposure, increased CORT secretion in 8-day- old normally reared mice suggesting that during the stress hyporesponsive period, the HPA axis is capable of responding only to specific stimuli. Changes in HPA axis activity and UVZ rateresulting from maternal deprivation and/or CDP challenge do not seem to be directly related. ©1994 John Wiley & Sons, Inc.     

Absence of TREM2 polymorphisms in patients with Alzheimer's disease and Frontotemporal Lobar Degeneration

Triggering Receptor Expressed on Myeloid cells (TREM)2 deficiency originates a genetic syndrome characterized by bone cysts and presenile dementia, named Nasu-Hakola disease (NHD). Early onset dementia and marked involvement of frontal regions are features characterizing both NHD and other kinds of neurodegenerative disorders, such as Frontotemporal Lobar Degeneration (FTLD), and, in some cases, Alzheimer's disease (AD). Three Single Nucleotide Polymorphisms (SNPs) in TREM2 coding region were screened by allelic discrimination in a population of probable AD patients as well as FTLD patients as compared with age-matched controls. In addition, mutation scanning of the coding region of TREM2 gene was carried out in 7 patients with early onset AD (EOAD), 16 FTLD, and 20 controls. None of the SNPs analyzed was present, either in patients or controls. Moreover, mutation scanning of the five exons of TREM2 failed to detect the presence of novel polymorphisms. These data demonstrate that TREM2 coding region is highly conserved, implying a crucial role of this receptor. Further studies, including a functional analysis, are certainly required to clarify the role of TREM2 in neurodegenerative processes.     

Age-dependent changes in the susceptibility to apoptosis of peripheral blood CD4+ and CD8+ T lymphocytes with virgin or memory phenotype

Susceptibility to apoptosis changes with age and most of the available data on lymphocytes refer to mitogen stimulated cells. We studied this susceptibility in quiescent, purified CD4+ or CD8+ T cells from a group of Italian old people compared with a group of young people. We found that an apoptotic agent such as 2-deoxy-D-ribose (dRib), which acts via glutathione depletion and oxidative stress, was more effective in CD4+ T cells from young donors, while no difference was found in CD8+ T cells. On the contrary, another agent such as TNF-alpha, which acts via receptor engagement, was more effective in CD8+ T cells from old subjects, and no difference was found in CD4+ T cells. When marker of activation-memory were investigated, no difference between young and old subjects was found when dRib was used. Differently, when TNF-alpha was used, memory and activated CD4+ T cells from old donors were less sensitive than younger counterparts, while memory CD8+ T cells from old donors were more sensitive than younger counterparts. This suggests that age-related changes in susceptibility to apoptosis of resting T cells largely depend on the type of the apoptotic stimulus which is used as well as on the memory phenotype of the cells. These results may also account, at least in part, for the deep remodelling of T cell repertoire that occurs during ageing.     

The fine structure of the myoneural junctions in the body wall muscles in Branchiobdella pentodonta whit. (Annelida,oligochaeta)

The ultrastructure of the myoneural junctions in the body wall muscles has been studied in Branchiobdella pentodonta Whit. A single junctional type has been found. Within the terminal axon there are two types of vesicles, which differ in number, size and electron opacity. The junctional gap contains the basement membrane. The post-junctional membrane displays concave patches on which slender projections arising from the outer lamina of the sarcolemma extend into the junctional gap. These concave patches overlie a cytoplasmic lamina made up of electron dense material.     

Differential signaling by CpG DNA in DCs and B cells: not just TLR9

CpG-containing oligodeoxynucleotides (CpG ODNs) act on Toll-like receptor 9 (TLR9) that is expressed on B cells and plasmacytoid dendritic cells (pDCs) to stimulate the innate immune system, however, different types of CpG ODNs induce distinct responses. Recent papers suggest some CpG ODNs could require a second receptor or cofactor to signal. The different signaling complexes assembled might impact on the affinity with which CpG ODNs signal to TLR9 or activate additional pathways that lead to distinct immune responses.     

Cation channels,cell volume and the death of an erythrocyte

Similar to a variety of nucleated cells, human erythrocytes activate a non-selective cation channel upon osmotic cell shrinkage. Further stimuli of channel activation include oxidative stress, energy depletion and extracellular removal of Cl^–. The channel is permeable to Ca²⁺ and opening of the channel increases cytosolic [Ca²⁺]. Intriguing evidence points to a role of this channel in the elimination of erythrocytes by apoptosis. Ca²⁺ entering through the cation channel stimulates a scramblase, leading to breakdown of cell membrane phosphatidylserine asymmetry, and stimulates Ca²⁺-sensitive K⁺ channels, thus leading to KCl loss and (further) cell shrinkage. The breakdown of phosphatidylserine asymmetry is evidenced by annexin binding, a typical feature of apoptotic cells. The effects of osmotic shock, oxidative stress and energy depletion on annexin binding are mimicked by the Ca²⁺ ionophore ionomycin (1 µM) and blunted in the nominal absence of extracellular Ca²⁺. Nevertheless, the residual annexin binding points to additional mechanisms involved in the triggering of the scramblase. The exposure of phosphatidylserine at the extracellular face of the cell membrane stimulates phagocytes to engulf the apoptotic erythrocytes. Thus, sustained activation of the cation channels eventually leads to clearance of affected erythrocytes from peripheral blood. Susceptibility to annexin binding is enhanced in several genetic disorders affecting erythrocyte function, such as thalassaemia, sickle-cell disease and glucose-6-phosphate dehydrogenase deficiency. The enhanced vulnerability presumably contributes to the shortened life span of the affected erythrocytes. Beyond their role in the limitation of erythrocyte survival, cation channels may contribute to the triggering of apoptosis in nucleated cells exposed to osmotic shock and/or oxidative stress.     

Primary cutaneous large B-cell lymphoma of the leg: histogenetic analysis of a controversial clinicopathologic entity

This study analyzes the pathologic and molecular features of 5 cases of primary cutaneous large B-cell lymphoma of the leg (PCLBCL-leg), recently included in the European Organization for Research and Treatment of Cancer (EORTC) classification of primary cutaneous lymphoma. PCLBCL-leg accounts for 5% to 10% of all primary cutaneous B-cell lymphoma (PCBCL), usually affects elderly patients and carries a worse prognosis than other forms of PCBCL. It has been proposed that the malignant cells of PCLBCL-leg originate from germinal center (GC)-related cells, but their effective normal counterpart is unclear, and the rationale behind the inclusion of this lymphoma as a separate entity is based on its prognosis rather than on its proved histogenesis. All of our cases of PCLBCL-leg morphologically resembled diffuse large B-cell lymphoma (DLBCL), but to better define their histogenesis, we also analyzed various phenotypic and genotypic markers, including mutations of the Ig and of BCL-6 genes, as well as expression of the bcl-6, MUM1, and CD138/syndecan-1 proteins. Immunohistochemically, all of our cases stained for the L-26/CD20cy and CD79a antigens and expressed the bcl-2, bcl-6, and MUM-1 proteins but were negative for both the CD10/CALLA and CD138 antigens. With respect to molecular analysis, the lymphoma population of all PCLBCL-leg carried hypermutation of Ig genes, and all but 1 case also harbored mutations of the BCL-6 gene. Our results indicate that PCLBCL-leg are similar both under the morphofunctional and molecular profiles to most DLBCL of other sites. Thus, caution seems justified before definitely considering PCLBCL of the leg as a distinct entity.     

A patient with novel MBOAT7 variant: The cerebellar atrophy is progressive and displays a peculiar neurometabolic profile

Mutations in the MBOAT7 gene have been described in 43 patients, belonging to 18 families, showing nonspecific clinical features (intellectual disability [ID], seizures, microcephaly or macrocephaly, and mild to moderate cerebellar atrophy) that make the clinical diagnosis difficult. Here we report the first Italian patient, a 22.5‐year‐old female, one of the oldest reported, born to apparently consanguineous parents. She shows severe ID, macrocephaly, seizures, aggressive outbursts, hyperphagia. We also documented progressive atrophy of the cerebellar vermis, that appeared not before the age of 7. The whole‐exome sequencing of the trio identified a novel homozygous variant c.1057_1058delGCinsCA (p.Ala353His) in the MBOAT7 gene. The variant is considered to be likely pathogenic, since it is absent from population database and it lies in a highly conserved amino acid residue. This disorder has a neurometabolic pathogenesis, implicating a phospholipid remodeling abnormalities. A brain hydrogen‐magnetic resonance spectroscopy (H‐MRS) examination in our patient disclosed a peculiar neurometabolic profile in the cerebellar hemispheric region. This new finding could address the clinical suspicion of MBOAT7‐related disorder, among the wide range of genetic conditions associated with ID and cerebellar atrophy. Moreover, the documented progression of cerebellar atrophy and the worsening of the disease only after some years open to the possibility of a therapeutic window after birth.     

Mild phenotype in two unrelated patients with a partial deletion of 21q22.2-q22.3 defined by FISH and molecular studies

We describe two unrelated patients with cytogenetically visible deletions of 21q22.2-q22.3 and mild phenotypes. Both patients presented minor dysmorphic features including thin marfanoid build, facial asymmetry, downward-slanting palpebral fissures, depressed nasal bridge, small nose with bulbous tip, and mild mental retardation (MR). FISH and molecular studies indicated common deleted areas but different breakpoints. In patient 1, the breakpoint was fine mapped to a 5.2 kb interval between exon 5 and exon 8 of the ETS2 gene. The subtelomeric FISH probe was absent on one homologue 21 indicating a terminal deletion spanning approximately 7.9 Mb in size. In patient 2, the proximal breakpoint was determined to be 300-700 kb distal to ETS2, and the distal breakpoint 2.5-0.3 Mb from the 21q telomere, indicating an interstitial deletion sized approximately 4.7-7.3 Mb. The 21q- syndrome is rare and typically associated with a severe phenotype, but different outcomes depending on the size and location of the deleted area have been reported. Our data show that monosomy 21q of the area distal to the ETS2 gene, representing the terminal 7.9 Mb of 21q, may result in mild phenotypes comprising facial anomalies, thin marfanoid build, and mild MR, with or without signs of holoprosencephaly.