In vivo modulation of FGF biological activity alters cranial suture fate

Gain-of-function mutations in fibroblast growth factor receptors have been identified in numerous syndromes associated with premature cranial suture fusion. Murine models in which the posterior frontal suture undergoes programmed fusion after birth while all other sutures remain patent provide an ideal model to study the biomolecular mechanisms that govern cranial suture fusion. Using adenoviral vectors and targeted in utero injections in rats, we demonstrate that physiological posterior frontal suture fusion is inhibited using a dominant-negative fibroblast growth factor receptor-1 construct, whereas the normally patent coronal suture fuses when infected with a construct that increases basic fibroblast growth factor biological activity. Our data may facilitate the development of novel, less invasive treatment options for children with craniosynostosis.     

Coronal craniosynostosis due to TCF12 mutations in patients from Turkey

Craniosynostosis consists of premature fusion of one or more cranial sutures and can be seen as part of a syndrome or diagnosed as nonsyndromic (isolated). Although more than 180 craniosynostosis syndromes have been identified, 70% of the cases are diagnosed as nonsyndromic. On the other hand, genetic causes of the cases are mostly unknown and the overall frequency of the genetic diagnosis is around 25%. In this study, we used targeted Next Generation Sequencing (NGS) analysis to identify the genetic variations of two craniosynostosis cases. We have identified two different truncating mutations, a known NM_207036.1:c.778_779delAT;p.(Met260Valfs*5) and a novel NM_207036.1:c.1102_1108delTCACCTC;p.(Pro369Glnfs*26) TCF12 variants. Additionally, upon physical examination of these two cases, we have observed some shared clinical similarities as well as differences such as bilateral simian crease and hidden cleft palate. This is the first study that reports the TCF12 mutations in Turkish patients with coronal suture synostosis.     

Cranial Suture Biology of the Aleutian Island Inhabitants

Research on cranial suture biology suggests there is biological and taxonomic information to be garnered from the heritable pattern of suture synostosis. Suture synostosis along with brain growth patterns, diet, and biomechanical forces influence phenotypic variability in cranial vault morphology. This study was designed to determine the pattern of ectocranial suture synostosis in skeletal populations from the Aleutian Islands. We address the hypothesis that ectocranial suture synostosis pattern will differ according to cranial vault shape. Ales Hrdlicka identified two phenotypes in remains excavated from the Aleutian Island. The Paleo‐Aleutians, exhibiting a dolichocranic phenotype with little prognathism linked to artifacts distinguished from later inhabitants, Aleutians, who exhibited a brachycranic phenotype with a greater amount of prognathism. A total of 212 crania representing Paleo‐Aleuts and Aleutian as defined by Hrdlicka were investigated for suture synostosis pattern following standard methodologies. Comparisons were performed using Guttmann analyses. Results revealed similar suture fusion patterns for the Paleo‐Aleut and Aleutian, a strong anterior to posterior pattern of suture fusion for the lateral‐anterior suture sites, and a pattern of early termination at the sagittal suture sites for the vault. These patterns were found to differ from that reported in the literature. Because these two populations with distinct cranial shapes exhibit similar patterns of suture synostosis it appears pattern is independent of cranial shape in these populations of Homo sapiens. These findings suggest that suture fusion patterns may be population dependent and that a standardized methodology, using suture fusion to determine age‐at‐death, may not be applicable to all populations. Anat Rec, 2011. © 2011 Wiley‐Liss, Inc.     

Recent advances in the pathophysiology, diagnosis and treatment of hereditary hemochromatosis and other iron overload syndromes

Recent years have witnessed tremendous advances in the fields of pathophysiology, diagnosis and management of hereditary hemochromatosis (HH) and other iron overload syndromes, the dreadful consequences of which are fully preventable by early diagnosis and treatment. Missense mutations in HFE, a newly discovered gene encoding for a major histocompatibility class-I like molecule, have been found to be strictly associated with most cases of HH. The mechanisms by which a dysfunctional HFE molecule determines increased absorption of iron in HH are on the way to be fully clarified, due to the availability of a knockout mouse model. Epidemiologic studies have shown that HH is one of the most common human hereditary disorders. The possibility to identify HFE heterozygotes by means of a simple genetic test have prompted studies on the association between HFE mutations and iron overload syndromes different from HH. In the era of the historic completion of the human genome projects, genetic testing for HH may soon qualify for being adopted in universal population screening policies. In the present paper, the recent advances in the fields of genetics and pathophysiology of HH and other iron overload syndromes will be summarized. Furthermore, its clinical features, pathology and treatment will be reviewed, and the emerging issues of cost-effective diagnosis and of possible population screening strategies will be succintly discussed.     

Craniosynostosis: genes and mechanisms

Enlargement of the skull vault occurs by appositional growth at the fibrous joints between the bones, termed cranial sutures. Relatively little is known about the developmental biology of this process, but genetically determined disorders of premature cranial suture fusion (craniosynostosis) provide one route to the identification of some of the key molecules involved. Mutations of the MSX2, FGFR1, FGFR2, FGFR3 and TWIST genes yield new insights, both into normal and abnormal cranial suture biogenesis and into problems of broad interest, such as the conservation of molecular pathways in development, and mechanisms of mutation and dominance.      

Human natural killer cell deficiencies

PURPOSE OF REVIEW: Human natural killer cell deficiencies are a relevant clinical entity that provides insight into the role of natural killer cells in host defense, as well as the basic biology of natural killer cells. Since previously reviewing these disorders, significant developments warrant their reconsideration. RECENT FINDINGS: Human natural killer cell deficiencies can occur as part of a more pervasive immunodeficiency syndrome or, rarely, in isolation. The most informative examples of the former are in the context of a known genetic defect, because the deficiency of natural killer cell development or activity can be attributed to the specific gene function. Since last reviewed, there are five human gene mutations that are now appreciated to affect natural killer cells, and additional new insights into natural killer cell biology have been obtained through seven others. Six new reports of isolated natural killer cell deficiencies, as well as a suggested classification scheme, are also reviewed. SUMMARY: Appreciation of human genetic syndromes that include natural killer cell deficiencies, as well as new cases of isolated natural killer cell deficiencies, continue to advance the understanding of natural killer cell biology and solidify the role of natural killer cells in defense against human herpesviral infection.     

Genetics of endocrine tumours

Major advances have been made in the understanding of the genetic mechanisms underlying endocrine tumorigenesis, through the study of several syndromes of genetic predisposition and the identification of the genes involved. The syndrome of type 1 multiple endocrine neoplasia (MEN-1) is one of the best known; this autosomal dominant hereditary syndrome predisposes to the development of endocrine tumors of the pituitary, the parathyroids, the foregut and the adrenals. The responsible gene, known as MEN-1, encodes an original protein, menin, involved in several major cellular functions, such as the control of cell proliferation and differentiation. Type 2 multiple endocrine neoplasia (MEN-2) is an autosomal dominant hereditary syndrome associated with the development of medullary carcinomas of the thyroid, pheochromocytomas and hyperparathyroidism; the corresponding gene, RET, encodes a transmembrane receptor with tyrosine kinase activity. Endocrine tumors are also associated with non Hippel-Lindau disease and with phacomatoses, such as type 1 neurofibromatosis and tuberous sclerosis. Finally, isolated familial syndromes of endocrine tumors have been described: isolated familial hyperparathyroidism type II (HRPT2), associated with alterations in a gene coding for an original protein, parafibromin, or isolated familial syndromes of pheochromocytomas and paragangliomas (PRG) associated with mutations in the genes SDHB, SDHC or SDHD, which encode succinate-dehydrogenase subunits. The understanding of the genetic mechanisms underlying these syndromes of predisposition is essential for the diagnosis and management of these patients and their family; it also gives insight on the molecular mechanisms of endocrine tumorigenesis.     

Timing of ectocranial suture activity in Gorilla gorilla as related to cranial volume and dental eruption

Research has shown that Pan and Homo have similar ectocranial suture synostosis patterns and a similar suture ontogeny (relative timing of suture fusion during the species ontogeny). This ontogeny includes patency during and after neurocranial expansion with a delayed bony response associated with adaptation to biomechanical forces generated by mastication. Here we investigate these relationships for Gorilla by examining the association among ectocranial suture morphology, cranial volume (as a proxy for neurocranial expansion) and dental development (as a proxy for the length of time that it has been masticating hard foods and exerting such strains on the cranial vault) in a large sample of Gorilla gorilla skulls. Two-hundred and fifty-five Gorilla gorilla skulls were examined for ectocranial suture closure status, cranial volume and dental eruption. Regression models were calculated for cranial volumes by suture activity, and Kendall's tau (a non-parametric measure of association) was calculated for dental eruption status by suture activity. Results suggest that, as reported for Pan and Homo, neurocranial expansion precedes suture synostosis activity. Here, Gorilla was shown to have a strong relationship between dental development and suture activity (synostosis). These data are suggestive of suture fusion extending further into ontogeny than brain expansion, similar to Homo and Pan. This finding allows for the possibility that masticatory forces influence ectocranial suture morphology.     

Molecular mechanisms of congenital heart disease

BackgroundCongenital heart disease (CHD) is the most common type of birth defect. Despite the many advances in our understanding of cardiac development and many genes related to cardiac development identified, the fundamental etiology for the majority of cases of congenital heart disease remains unknown.MethodsThis review summarizes normal cardiac development, outlines the recent discoveries of the genetic causes of CHD, and provides possible strategies for exploring them.ResultsCHD is a multifactorial complex disease, with environmental and genetic factors playing important roles. A number of causative genes of selected congenital heart defects and genetic syndromes have been found. The molecular mechanisms of CHD may include mutations in components of the cardiac gene network, altered haemodynamics, regulatory pathway of cardiac genes, micro-RNA dysfunction, epigenetics, adult congenital heart diseases, and so on.ConclusionsThe molecular basis of CHD is an exciting and rapidly evolving field. The continuing advances in the understanding of the molecular mechanisms of CHD will hopefully result in improved genetic counseling and care of affected individuals and their families.     

The epigenomics revolution in myelodysplasia: a clinico-pathological perspective

Rapid advances in molecular technologies are continually re-shaping the way we view and understand the mechanisms driving oncogenesis. The last decade has witnessed unparalleled change in the biology and therapy of the myelodysplastic syndromes (MDS), a heterogeneous collection of clonal myeloid disorders characterised by ineffective haematopoiesis and susceptibility to acute leukaemia transformation. Pivotal studies demonstrating the positive effects of hypomethylating agents on clinical outcome have brought an 'epigenomics revolution' to this disease, emphasising the importance of epigenetic mechanisms to the underlying pathogenesis of MDS. One of the most important future challenges in the MDS field will be to determine whether epigenetic therapies can be made more 'targeted' through identification of biomarkers which define subsets of patients most likely to benefit from treatment. A wave of novel mutations have recently been reported in MDS and other myeloid disorders, several of which regulate endogenous methylation networks within cells (including TET2, DNMT3A, IDH and EZH2). The relevance of these lesions in being able to predict response to epigenetic modulators and their correlation with epigenetic signatures in MDS are beginning to emerge.     

Familial endocrine tumours: pheochromocytomas and extra-adrenal paragangliomas – an update

Pheochromocytomas (PCC) and paragangliomas (PGL) are tumours occurring in the adrenal medulla and in extra-adrenal paraganglia, respectively. They have long been associated with familial occurrence and several syndromes had been described in which PCC formed an important component, including multiple endocrine neoplasia type 2, von Hippel-Lindau disease and neurofibromatosis type 1. Since the beginning of this millennium, both by the elucidation of specific genes, such as the various succinate dehydrogenase genes, as well as by generic molecular biology approaches, such as The Cancer Genome Atlas (TCGA) initiative, it was shown that the frequency of germline mutations in candidate genes for PCC and PGL has increased to 35–40%. In addition, somatic mutations have been shown to be much more frequent than previously thought, such that now 60–65% of these tumours harbour either a germline or a somatic mutation. This review gives an overview of the various syndromes and the genes involved, concluding with recommendations for genetic testing in the current era of genome wide analysis.     

FGF signaling in craniofacial biological control and pathological craniofacial development

Fibroblast growth factor receptors comprise a family of four evolutionarily conserved transmembrane proteins (FGFR1, FGFR2, FGFR3 and FGFR4) known to be critical for the normal development of multiple organ systems. In this review we will primarily focus upon the role of FGF/FGFR signaling as it influences the development of the craniofacial skeleton. Signaling by FGF receptors is regulated by the tissue-specific expression of FGFR isoforms, receptor subtype specific fibroblast growth factors and heparin sulfate proteoglycans. Signaling can also be limited by the expression of endogenous inhibitors. Gain-of-function mutations in FGFRs are associated with a series of congenital abnormality syndromes referred to as the craniosynostosis syndromes. Craniosynostosis is the clinical condition of premature cranial bone fusion and patients who carry craniosynostosis syndrome-associated mutations in FGFRs commonly have abnormalities of the skull vault in the form of craniosynostosis. Patients may also have abnormalities in the facial skeleton, vertebrae and digits. In this review we will discuss recent in vitro and in vivo studies investigating biologic mechanisms by which signaling through FGFRs influences skeletal development and can lead to craniosynostosis.     

KRAS gene mutations in Noonan syndrome familial cases cluster in the vicinity of the switch II region of the G-domain: report of another family with metopic craniosynostosis

Noonan syndrome (NS) and Noonan-related disorders [cardio-facio-cutaneous (CFC), Costello, Noonan syndrome with multiple lentigines (NS-ML), and neurofibromatosis-Noonan syndromes (NFNS)] are a group of developmental disorders caused by mutations in genes of the RAS/MAPK pathway. Mutations in the KRAS gene account for only a small proportion of affected Noonan and CFC syndrome patients that present an intermediate phenotype between these two syndromes, with more frequent and severe intellectual disability in NS and less ectodermal involvement in CFC syndrome, as well as atypical clinical findings such as craniosynostosis. Recently, the first familial case with a novel KRAS mutation was described. We report on a second vertical transmission (a mother and two siblings) with a novel mutation (p.M72L), in which the proband has trigonocephaly and the affected mother and sister, prominent ectodermal involvement. Metopic suture involvement has not been described before, expanding the main different cranial sutures which can be affected in NS and KRAS gene mutations. The gene alteration found in the studied family is in close proximity to the one reported in the other familial case (close to the switch II region of the G-domain), suggesting that this specific region of the gene could have less severe effects on intellectual ability than the other KRAS gene mutations found in NS patients and be less likely to hamper reproductive fitness.     

Human mutations affecting aging--a review.

A review of human genetic mutations that affect aging and their potential contribution to help understand normal aging processes is presented. The lifespans of most animal species, including man, have a genetically determined maximum. The lifespan of man appears to have evolved exceedingly rapidly, which suggests that relatively few genes may determine longevity. Analysis of biochemical evolution suggests that the regulation of enzyme levels may underlie most evolutionary changes. There is a wide spectrum of human genetic mutations. Some, such as progeria and Werner's syndrome, produce a phenotype resembling premature aging and may involve genes related to the aging process. Certain human chromosomal abnormalities, such as Down's syndrome, produce an appearance of premature aging and may be due to abnormal gene regulatory mechanisms. Progress in understanding the genetic mechanisms underlying aging is likely to come from elucidation of the molecular defects that result in the premature aging syndromes and from insights gained regarding the regulatory mechanisms governing eukaryotic genetic expression.