A novel cyclin encoded by a bcl1-linked candidate oncogene

We have previously identified a candidate oncogene (PRAD1 or D11S287E) on chromosome 11q13 which is clonally rearranged with the parathyroid hormone locus in a subset of benign parathyroid tumours. We now report that a cloned human placental PRAD1 complementary DNA encodes a protein of 295 amino acids with sequence similarities to the cyclins. Cyclins can form a complex with and activate p34cdc2 protein kinase, thereby regulating progress through the cell cycle. PRAD 1 messenger RNA levels vary dramatically across the cell cycle in HeLa cells. Addition of the PRAD1 protein to interphase clam embryo lysates containing inactive p34cdc2 kinase and lacking endogenous cyclins allows it to be isolated using beads bearing p13suc1, a yeast protein that binds cdc2 and related kinases with high affinity and coprecipitates kinase-associated proteins. Addition of PRAD1 also induces phosphorylation of histone H1, a preferred substrate of cdc2. These data suggest that PRAD1 encodes a novel cyclin whose overexpression may play an important part in the development of various tumours with abnormalities in 11q13.

Angiopoietin-1 regulates endothelial cell survival through the phosphatidylinositol 3'-Kinase/Akt signal transduction pathway

Angiopoietin-1 (Ang1) is a strong apoptosis survival factor for endothelial cells. In this study, the receptor/second messenger signal transduction pathway for the antiapoptotic effect of Ang1 on human umbilical vein endothelial cells was examined. Pretreatment with soluble Tie2 receptor, but not Tie1 receptor, blocked the Ang1-induced antiapoptotic effect. Ang1 induced phosphorylation of Tie2 and the p85 subunit of phosphatidylinositol 3'-kinase (PI 3'-kinase) and increased PI 3'-kinase activity in a dose-dependent manner. The PI 3'-kinase-specific inhibitors wortmannin and LY294002 blocked the Ang1-induced antiapoptotic effect. Ang1 induced phosphorylation of the serine-threonine kinase Akt at Ser473 in a PI 3'-kinase-dependent manner. Expression of a dominant-negative form of Akt reversed the Ang1-induced antiapoptotic effect. Ang1 mRNA and protein were present in vascular smooth muscle cells but not in endothelial cells. Cultured vascular smooth muscle cells, but not human umbilical vein endothelial cells, secreted Ang1. These findings indicate that the Tie2 receptor, PI 3'-kinase, and Akt are crucial elements in the signal transduction pathway leading to endothelial cell survival induced by the paracrine activity of Ang1.

Sequencing chromosomal abnormalities reveals neurodevelopmental loci that confer risk across diagnostic boundaries

Balanced chromosomal abnormalities (BCAs) represent a relatively untapped reservoir of single-gene disruptions in neurodevelopmental disorders (NDDs). We sequenced BCAs in patients with autism or related NDDs, revealing disruption of 33 loci in four general categories: (1) genes previously associated with abnormal neurodevelopment (e.g., AUTS2, FOXP1, and CDKL5), (2) single-gene contributors to microdeletion syndromes (MBD5, SATB2, EHMT1, and SNURF-SNRPN), (3) novel risk loci (e.g., CHD8, KIRREL3, and ZNF507), and (4) genes associated with later-onset psychiatric disorders (e.g., TCF4, ZNF804A, PDE10A, GRIN2B, and ANK3). We also discovered among neurodevelopmental cases a profoundly increased burden of copy-number variants from these 33 loci and a significant enrichment of polygenic risk alleles from genome-wide association studies of autism and schizophrenia. Our findings suggest a polygenic risk model of autism and reveal that some neurodevelopmental genes are sensitive to perturbation by multiple mutational mechanisms, leading to variable phenotypic outcomes that manifest at different life stages.

Disruption of neurexin 1 associated with autism spectrum disorder

Autism is a neurodevelopmental disorder of complex etiology in which genetic factors play a major role. We have implicated the neurexin 1 (NRXN1) gene in two independent subjects who display an autism spectrum disorder (ASD) in association with a balanced chromosomal abnormality involving 2p16.3. In the first, with karyotype 46,XX,ins(16;2)(q22.1;p16.1p16.3)pat, NRXN1 is directly disrupted within intron 5. Importantly, the father possesses the same chromosomal abnormality in the absence of ASD, indicating that the interruption of alpha-NRXN1 is not fully penetrant and must interact with other factors to produce ASD. The breakpoint in the second subject, with 46,XY,t(1;2)(q31.3;p16.3)dn, occurs approximately 750 kb 5' to NRXN1 within a 2.6 Mb genomic segment that harbors no currently annotated genes. A scan of the NRXN1 coding sequence in a cohort of ASD subjects, relative to non-ASD controls, revealed that amino acid alterations in neurexin 1 are not present at high frequency in ASD. However, a number of rare sequence variants in the coding region, including two missense changes in conserved residues of the alpha-neurexin 1 leader sequence and of an epidermal growth factor (EGF)-like domain, respectively, suggest that even subtle changes in NRXN1 might contribute to susceptibility to ASD.

X-linked protocadherin 19 mutations cause female-limited epilepsy and cognitive impairment

Epilepsy and mental retardation limited to females (EFMR) is a disorder with an X-linked mode of inheritance and an unusual expression pattern. Disorders arising from mutations on the X chromosome are typically characterized by affected males and unaffected carrier females. In contrast, EFMR spares transmitting males and affects only carrier females. Aided by systematic resequencing of 737 X chromosome genes, we identified different protocadherin 19 (PCDH19) gene mutations in seven families with EFMR. Five mutations resulted in the introduction of a premature termination codon. Study of two of these demonstrated nonsense-mediated decay of PCDH19 mRNA. The two missense mutations were predicted to affect adhesiveness of PCDH19 through impaired calcium binding. PCDH19 is expressed in developing brains of human and mouse and is the first member of the cadherin superfamily to be directly implicated in epilepsy or mental retardation.

Molecular cloning and chromosomal mapping of DNA rearranged with the parathyroid hormone gene in a parathyroid adenoma

Parathyroid adenomas are common benign neoplasms for which no chromosomal defects have been described. We recently found two parathyroid adenomas bearing clonal restriction fragment abnormalities involving the PTH locus, and now show that in one of these tumors: (a) a DNA rearrangement occurred at the PTH locus; (b) the rearrangement separated the PTH gene's 5' flanking region from its coding exons, conceivably placing a newly adjacent gene under the influence of PTH regulatory elements; (c) the DNA that recombined with PTH normally maps to 11q13, the known chromosomal location of several oncogenes and the gene for multiple endocrine neoplasia type I; and (d) the rearrangement was a reciprocal, conservative recombination of the locus on 11q13 (Human Gene Mapping Library assignment D11S287) with PTH (on 11p15). These data provide molecular cytogenetic evidence for the clonal occurrence of a major chromosome 11 aberrancy in this benign parathyroid tumor. The D11S287 clone could prove useful in genetic linkage analyses, in determining precise 11q13 breakpoints in other neoplasms, and in identifying a gene on chromosome 11 that may participate in parathyroid tumor development.

Monoclonality and abnormal parathyroid hormone genes in parathyroid adenomas

Previous work based on the relative tissue content of glucose-6-phosphate dehydrogenase isoenzymes suggested that parathyroid adenomas, like primary hyperplasia, may be multicellular (not clonal) in origin. We have reexamined this issue by using two independent molecular genetic methods. We report tumor-cell-specific restriction-fragment-length alterations involving the parathyroid hormone gene from two human parathyroid adenomas. These abnormal restriction fragments indicate that in each case a clonal proliferation of cells was present and also suggest that DNA alterations involving the parathyroid hormone locus may be important in the tumorigenesis or clonal evolution of some parathyroid adenomas. In addition, we used a restriction-fragment-length polymorphism in an X-linked gene (hypoxanthine phosphoribosyltransferase) to examine the clonality of eight parathyroid adenomas in women. Of these eight adenomas, six had the DNA hybridization pattern of monoclonality, and two had an equivocal pattern. None of five hyperplastic parathyroid glands had a monoclonal pattern. We conclude that some (and perhaps many) single parathyroid adenomas are monoclonal neoplasms. Our observations suggest that there is a fundamental biologic difference between parathyroid adenomas and primary hyperplasia--a difference that could prove useful in distinguishing these entities clinically.

Adding posterior lumbar interbody fusion to pedicle screw fixation and posterolateral fusion after decompression in spondylolytic spondylolisthesis

STUDY DESIGN

This is a retrospective study analyzing 76 patients treated by decompression, pedicle screw instrumentation, and fusion for spondylolytic spondyiolisthesis with symptomatic spinal stenosis.

OBJECTIVES

To verify the advantages of adding posterior lumbar interbody fusion to the usual posterolateral fusion with pedicle screw instrumentation.

SUMMARY OF BACKGROUND DATA

Stabilization after decompression of spondylolytic spondylolisthesis is difficult because of a lack of fusional bone bases, gap between the transverse process bases, and incompetent anterior disc support. Posterior lumbar interbody fusion offers anterior support, reduction, and a broad fusion base.

METHODS

Forty patients were treated with posterolateral fusion, and 36 were treated with additional posterior lumbar interbody fusion. They were compared for union, reduction of the deformity, and clinical results.

RESULTS

The patients were followed up for more than 2 years. Nonunion was observed in three patients who underwent posterolateral fusion (7.5%), and no cases of nonunion was found in patients who underwent posterior lumbar interbody fusion. Reduction of slippage was 28.3% in those who underwent posterolateral fusion and 41.6% in those who had posterior lumbar interbody fusion (P = 0.05). In the posterolateral fusion group, eight patients (20%) had recurrence of deformity, with loss of reduction more than 50%. Hardware failures occurred in two patients who had posterolateral fusion. There was no major neurologic complications in both groups. Both groups had satisfactory results in more than 90% of patients, with marked improvement of claudication. However, subjective improvement of back pain by Kirkaldy-Willis criteria revealed differences in the excellent results. An excellent result was reported by 45% in the posterolateral fusion group and by 75% in posterior lumbar interbody fusion group.

CONCLUSIONS

The addition of posterior lumbar interbody fusion to posterolateral fusion after a complete decompression and pedicle screw fixation is a recommended procedure for the treatment of spondylolytic spondylolishesis with spinal stenosis.

Angiopoietin-1 induces endothelial cell sprouting through the activation of focal adhesion kinase and plasmin secretion

Angiopoietin-1 (Ang1) is a strong inducer of endothelial cell sprouting, which is a first step in both angiogenesis and neovascularization. We examined the mechanisms underlying Ang1-induced cell sprouting using porcine pulmonary artery endothelial cells. Ang1 induced the nondirectional and directional migration of endothelial cells mediated through the Tie2 but not the Tie1 receptor. Ang1 induced tyrosine phosphorylation of p125(FAK), and this phosphorylation was dependent on phosphatidylinositol (PI) 3'-kinase activity. Ang1 induced the secretion of plasmin and matrix metalloproteinase-2 (MMP-2), which is inhibited by PI 3'-kinase inhibitors. Ang1 also induced the secretion of small amounts of proMMP-3 and proMMP-9 but not proMMP-1. Ang1 suppressed the secretion of tissue inhibitor of metalloproteinase-2 (TIMP-2), but not of TIMP-1. Addition of alpha(2)-antiplasmin, a combination of TIMP-1 and TIMP-2, or PI 3'-kinase inhibitors inhibited Ang1-induced sprouting activity. Therefore, Ang1-induced sprouting activity in endothelial cells may be accomplished by cytoskeletal changes and secretion of proteinases and may be largely mediated through intracellular PI 3'-kinase activation.

Coadministration of angiopoietin-1 and vascular endothelial growth factor enhances collateral vascularization

Using growth factors to induce vasculogenesis is a promising approach in the treatment of ischemic legs and myocardium. Because the vasculogenesis requires a cascade of growth factors, their receptors, and intracellular signals, such therapies may require the application of more than a single growth factor. We examined the effect of 2 endothelial cell-specific growth factors, angiopoietin-1 (Ang1) and vascular endothelial growth factor (VEGF), on primary cultured porcine coronary artery endothelial cells. VEGF, but not Ang1, increased DNA synthesis and cell number. Ang1 or VEGF induced migration and sprouting activity, increased plasmin and matrix metalloproteinase-2 secretion, and decreased tissue inhibitors of metalloproteinase type 2 secretion. A combination of the submaximal doses of Ang1 and VEGF enhanced these effects and was more potent than the maximal dose of either alone. In a rabbit ischemic hindlimb model, a combination of Ang1 and VEGF gene delivery produced an enhanced effect on resting and maximal blood flow and capillary formation that was greater than that of either factor alone. Angiographic analyses revealed that larger blood vessels were formed after gene delivery of Ang1 or Ang1 plus VEGF than after VEGF gene delivery. These results suggest that combined treatment of Ang1 and VEGF could be used to produce therapeutic vascularization.

Disruption of ROBO2 is associated with urinary tract anomalies and confers risk of vesicoureteral reflux

Congenital anomalies of the kidney and urinary tract (CAKUT) include vesicoureteral reflux (VUR). VUR is a complex, genetically heterogeneous developmental disorder characterized by the retrograde flow of urine from the bladder into the ureter and is associated with reflux nephropathy, the cause of 15% of end-stage renal disease in children and young adults. We investigated a man with a de novo translocation, 46,X,t(Y;3)(p11;p12)dn, who exhibits multiple congenital abnormalities, including severe bilateral VUR with ureterovesical junction defects. This translocation disrupts ROBO2, which encodes a transmembrane receptor for SLIT ligand, and produces dominant-negative ROBO2 proteins that abrogate SLIT-ROBO signaling in vitro. In addition, we identified two novel ROBO2 intracellular missense variants that segregate with CAKUT and VUR in two unrelated families. Adult heterozygous and mosaic mutant mice with reduced Robo2 gene dosage also exhibit striking CAKUT-VUR phenotypes. Collectively, these results implicate the SLIT-ROBO signaling pathway in the pathogenesis of a subset of human VUR.

Neurotrophin 3 potentiates neuronal activity and inhibits gamma-aminobutyratergic synaptic transmission in cortical neurons

Neurotrophins have traditionally been regarded as slowly acting signals essential for neuronal survival and differentiation. However, brain-derived neurotrophic factor and neurotrophin 3 (NT-3) have recently been reported to exert an acute potentiation of synaptic activity at the amphibian neuromuscular junction. Little is known about the role of neurotrophins on functional synapses in the central nervous system. Here we show that NT-3 rapidly increased the frequency of spontaneous action potentials, and it synchronized excitatory synaptic activities in developing cortical neurons. Moreover, the inhibitory synaptic transmission mediated by gamma-aminobutyric acid (GABA) subtype A receptors was found to be reduced by NT-3. Thus, the excitatory effects of NT-3 on spontaneous action potentials were attributable to a reduction of GABAergic transmission. Our findings, together with previous reports of rapid regulation of central nervous system neurotrophin expression by neuronal activity and of the role of GABAergic transmission in cortical plasticity, suggest a mechanism for modulation of synaptic transmission and activity-dependent synaptic modulation in cortical neurons.

Human chromosome 7: DNA sequence and biology

DNA sequence and annotation of the entire human chromosome 7, encompassing nearly 158 million nucleotides of DNA and 1917 gene structures, are presented. To generate a higher order description, additional structural features such as imprinted genes, fragile sites, and segmental duplications were integrated at the level of the DNA sequence with medical genetic data, including 440 chromosome rearrangement breakpoints associated with disease. This approach enabled the discovery of candidate genes for developmental diseases including autism.

Combined modality therapy of A431 human epidermoid cancer using anti-EGFr antibody C225 and radiation

BACKGROUND

Monoclonal antibodies (mAb) to epidermal growth factor receptor (EGFr) inhibit tumor cell proliferation and enhance cytotoxicity of chemotherapeutic agents. The purpose of this study was to investigate the interaction of the anti-EGFr antibody C225 combined with radiotherapy (RT) on EGFr expressing A431 human epidermoid cancer cells.

METHODS

Cell proliferation, apoptosis, EGFr expression and phosphorylation, and clonogenic survival were assayed in vitro. A431 tumor growth inhibition and immunohistochemistry analysis of EGFr expression and apoptosis were assessed in vivo.

RESULTS

C225 plus RT produced greater inhibition of A431 cell proliferation than C225 or RT alone which was corroborated by enhanced apoptosis. Similar clonogenic survival occurred following the addition of C225 to RT, although colonies were smaller in the presence of C225. C225 produced inhibition of EGF-induced phosphorylation of EGFr without concurrent down-regulation of surface receptor, which was not altered by RT. Combined treatment of mice bearing tumors demonstrated enhancement of complete regressions, reduction in time to tumor size doubling, and prolongation of survival. Significant apoptosis occurred in xenograft tumors treated with C225 with or without RT.

CONCLUSIONS

These data demonstrate an interaction between C225 and RT. C225-mediated apoptosis and inhibition of EGFr phosphorylation may be critical in the interaction. Studies to define the precise influence of combined modality treatment on the EGFr signal transduction cascade need to be pursued. The combination of growth factor receptor antibodies and RT has potential application in clinical oncology.

Contribution of copy number variants involving nonsense-mediated mRNA decay pathway genes to neuro-developmental disorders

The nonsense-mediated mRNA decay (NMD) pathway functions not only to degrade transcripts containing premature termination codons (PTC), but also to regulate the transcriptome. UPF3B and RBM8A, important components of NMD, have been implicated in various forms of intellectual disability (ID) and Thrombocytopenia with Absent Radius (TAR) syndrome, which is also associated with ID. To gauge the contribution of other NMD factors to ID, we performed a comprehensive search for copy number variants (CNVs) of 18 NMD genes among individuals with ID and/or congenital anomalies. We identified 11 cases with heterozygous deletions of the genomic region encompassing UPF2, which encodes for a direct interacting protein of UPF3B. Using RNA-Seq, we showed that the genome-wide consequence of reduced expression of UPF2 is similar to that seen in patients with UPF3B mutations. Out of the 1009 genes found deregulated in patients with UPF2 deletions by at least 2-fold, majority (95%) were deregulated similarly in patients with UPF3B mutations. This supports the major role of deletion of UPF2 in ID. Furthermore, we found that four other NMD genes, UPF3A, SMG6, EIF4A3 and RNPS1 are frequently deleted and/or duplicated in the patients. We postulate that dosage imbalances of these NMD genes are likely to be the causes or act as predisposing factors for neuro-developmental disorders. Our findings further emphasize the importance of NMD pathway(s) in learning and memory.

WDR11, a WD protein that interacts with transcription factor EMX1, is mutated in idiopathic hypogonadotropic hypogonadism and Kallmann syndrome

By defining the chromosomal breakpoint of a balanced t(10;12) translocation from a subject with Kallmann syndrome and scanning genes in its vicinity in unrelated hypogonadal subjects, we have identified WDR11 as a gene involved in human puberty. We found six patients with a total of five different heterozygous WDR11 missense mutations, including three alterations (A435T, R448Q, and H690Q) in WD domains important for β propeller formation and protein-protein interaction. In addition, we discovered that WDR11 interacts with EMX1, a homeodomain transcription factor involved in the development of olfactory neurons, and that missense alterations reduce or abolish this interaction. Our findings suggest that impaired pubertal development in these patients results from a deficiency of productive WDR11 protein interaction.

Clinical outcomes and risk factors of post-polypectomy coagulation syndrome: a multicenter, retrospective, case-control study

BACKGROUND AND STUDY AIMS

Post-polypectomy coagulation syndrome (PPCS) is a well known complication of colonoscopic polypectomy. However, no previous studies have reported on the clinical outcomes or risk factors of PPCS. The aim of the current study was to analyze the clinical outcomes and risk factors of PPCS developing after a colonoscopic polypectomy.

PATIENTS AND METHODS

Data for all patients who underwent colonoscopic polypectomies and required hospitalization in nine university hospitals were analyzed retrospectively. The incidence, clinicopathological characteristics, and clinical outcomes of PPCS cases were examined. Additionally, patients who developed PPCS were compared with controls who were matched by age and sex, in order to assess for possible risk factors.

RESULTS

The rate of PPCS that required hospitalization after colonoscopic polypectomy was 0.7/1000. All patients with PPCS were treated medically without the need for surgical interventions. The median durations of therapeutic fasting, hospitalization, and antibiotic use were 3 days, 5.5 days, and 7 days, respectively. The rates of major PPCS and mortality were 2.9 % and 0 %, respectively. On multivariate analysis, hypertension (OR = 3.023, 95 %CI 1.034 - 8.832), large lesion size (OR = 2.855, 95 %CI 1.027 - 7.937), and non-polypoid configuration (OR = 3.332, 95 %CI 1.029 - 10.791) were found to be independent risk factors related to the development of PPCS.

CONCLUSIONS

In this study, the rates of major PPCS and mortality were only 2.9 % and 0 %, respectively. Hypertension, large lesion size, and non-polypoid configuration of the lesion were independently associated with PPCS. Therefore, patients may be reassured by the excellent prognosis of PPCS, while endoscopists should be especially careful when performing colonoscopic polypectomies in patients with hypertension or large and non-polypoid lesions.

Delayed puberty and estrogen resistance in a woman with estrogen receptor α variant

Although androgen resistance has been characterized in men with a normal chromosome complement and mutations in the androgen-receptor gene, a mutation in the gene encoding estrogen receptor α (ESR1) was previously described only in one man and not, to our knowledge, in a woman. We now describe an 18-year-old woman without breast development and with markedly elevated serum levels of estrogens and bilateral multicystic ovaries. She was found to have a homozygous loss-of-function ESR1 mutation in a completely conserved residue that interferes with estrogen signaling. Her clinical presentation was similar to that in the mouse orthologue knockout. This case shows that disruption of ESR1 causes profound estrogen resistance in women. (Funded by the National Institutes of Health.).

Manganese: a transition metal protects nigrostriatal neurons from oxidative stress in the iron-induced animal model of parkinsonism

It has been suggested that transition metals such as iron and manganese produce oxidative injury to the dopaminergic nigrostriatal system. which may play a critical role in the pathogenesis of Parkinson's disease. Intranigral infusion of ferrous citrate (0 to 8.4 nmol, i.n.) acutely increased lipid peroxidation in the substantia nigra and dopamine turnover in the caudate nucleus. Subsequently, it caused a severe depletion of dopamine levels in the rat caudate nucleus. In contrast to iron's pro-oxidant effect, manganese (up to 30 nmol, i.n.) causes neither lipid peroxidation nor nigral injury/dopamine depletion. Manganese (1.05 to 4.2 nmol, i.n.) dose-dependently protected nigral neurons from iron-induced oxidative injury and dopamine depletion. Manganese also suppressed acute increase in dopamine turnover and contralateral turning behaviour induced by iron. In brain homogenates manganese (0 to 10 microM) concentration-dependently inhibited propagation of lipid peroxidation caused by iron (0 to 5 microM). Without the contribution of manganese-superoxide dismutase manganese was still effective in sodium azide and/or heat-pretreated brain homogenates. Surprisingly, iron but not manganese, catalysed the Fenton reaction or the conversion of hydrogen peroxide to hydroxyl radicals. The results indicate that iron and manganese are two transition metals mediating opposite effects in the nigrostriatal system, as pro-oxidant and antioxidant, respectively. In conclusion, intranigral infusion of iron, but not manganese, provides an animal model for studying the pathophysiological role of oxidant and oxidative stress in nigrostriatal degeneration and Parkinsonism. The present results further suggest that the atypical antioxidative properties of manganese may protect substantia nigra compacta neurons from iron-induced oxidative stress.

Characterization of apparently balanced chromosomal rearrangements from the developmental genome anatomy project

Apparently balanced chromosomal rearrangements in individuals with major congenital anomalies represent natural experiments of gene disruption and dysregulation. These individuals can be studied to identify novel genes critical in human development and to annotate further the function of known genes. Identification and characterization of these genes is the goal of the Developmental Genome Anatomy Project (DGAP). DGAP is a multidisciplinary effort that leverages the recent advances resulting from the Human Genome Project to increase our understanding of birth defects and the process of human development. Clinically significant phenotypes of individuals enrolled in DGAP are varied and, in most cases, involve multiple organ systems. Study of these individuals' chromosomal rearrangements has resulted in the mapping of 77 breakpoints from 40 chromosomal rearrangements by FISH with BACs and fosmids, array CGH, Southern-blot hybridization, MLPA, RT-PCR, and suppression PCR. Eighteen chromosomal breakpoints have been cloned and sequenced. Unsuspected genomic imbalances and cryptic rearrangements were detected, but less frequently than has been reported previously. Chromosomal rearrangements, both balanced and unbalanced, in individuals with multiple congenital anomalies continue to be a valuable resource for gene discovery and annotation.

The prevalence of digenic mutations in patients with normosmic hypogonadotropic hypogonadism and Kallmann syndrome

OBJECTIVE

To determine the prevalence of digenic mutations in patients with idiopathic hypogonadotropic hypogonadism (IHH) and Kallmann syndrome (KS).

DESIGN

Molecular analysis of DNA in IHH/KS patients.

SETTING

Academic medical center.

PATIENT(S)

Twenty-four IHH/KS patients with a known mutation (group 1) and 24 IHH/KS patients with no known mutation (group 2).

INTERVENTION(S)

DNA from IHH/KS patients was subjected to polymerase chain reaction-based DNA sequencing of the 13 most common genes (KAL1, GNRHR, FGFR1, KISS1R, TAC3, TACR3, FGF8, PROKR2, PROK2, CHD7, NELF, GNRH1, and WDR11).

MAIN OUTCOME MEASURE(S)

The identification of mutations absent in ≥188 ethnically matched controls. Both SIFT (sorting intolerant from tolerant) and conservation among orthologs provided supportive evidence for pathologic roles.

RESULT(S)

In group 1, 6 (25%) of 24 IHH/KS patients had a heterozygous mutation in a second gene, and in group 2, 13 (54.2%) of 24 had a mutation in at least one gene, but none had digenic mutations. In group 2, 7 (29.2%) of 24 had a mutation considered sufficient to cause the phenotype.

CONCLUSION(S)

When the 13 most common IHH/KS genes are studied, the overall prevalence of digenic gene mutations in IHH/KS was 12.5%. In addition, approximately 30% of patients without a known mutation had a mutation in a single gene. With the current state of knowledge, these findings suggest that most IHH/KS patients have a monogenic etiology.

Medial medullary syndrome. Report of 18 new patients and a review of the literature

BACKGROUND AND PURPOSE

With advanced imaging techniques, infarctions occurring in the medulla are now more easily identified. To date, however, only approximately 30 cases of medial medullary infarction syndrome (MMS) have been reported, and the clinical and radiological characteristics of MMS remain to be studied.

METHODS

We studied 18 patients (15 men, 3 women; mean age, 62 years) who had compatible clinical and MRI findings of MMS and reviewed the previously reported cases.

RESULTS

Seventeen patients had a unilateral lesion usually involving the upper medulla, and 1 had bilateral lesions. Fifteen patients had unilateral sensorimotor stroke, while 2 presented with pure motor stroke. The face was usually but not always spared. The degree of hemiparesis varied, and a tingling sensation with decreased vibration and position sense was the most common sensory manifestation. Two patients had lingual paresis, and none suffered respiratory difficulties. One patient presented with bilateral gait ataxia without sensorimotor dysfunction. Angiography or MR angiography performed in 9 patients showed vertebral artery disease in 6. Three patients had concurrent lateral medullary infarction, and 1 had a previous history of lateral medullary syndrome. The prognosis was generally good, although residual hemiparesis remained in patients with initially severe hemiparesis. Review of 26 previously reported cases showed that they frequently had bilateral lesions, often presenting with quadriplegia, lingual paresis, respiratory symptoms, and a grave prognosis.

CONCLUSIONS

Our data illustrate that MMS is most often manifested as benign hemisensorimotor stroke frequently associated with tingling sensation and impaired deep sensation. This benign form of MMS should be much more common than MMS with poor prognosis and may have been frequently misdiagnosed as capsular or pontine stroke before the era of MRI.

Zebrafish knockout of Down syndrome gene, DYRK1A, shows social impairments relevant to autism

BACKGROUND

DYRK1A maps to the Down syndrome critical region at 21q22. Mutations in this kinase-encoding gene have been reported to cause microcephaly associated with either intellectual disability or autism in humans. Intellectual disability accompanied by microcephaly was recapitulated in a murine model by overexpressing Dyrk1a which mimicked Down syndrome phenotypes. However, given embryonic lethality in homozygous knockout (KO) mice, no murine model studies could present sufficient evidence to link Dyrk1a dysfunction with autism. To understand the molecular mechanisms underlying microcephaly and autism spectrum disorders (ASD), we established an in vivo dyrk1aa KO model using zebrafish.

METHODS

We identified a patient with a mutation in the DYRK1A gene using microarray analysis. Circumventing the barrier of murine model studies, we generated a dyrk1aa KO zebrafish using transcription activator-like effector nuclease (TALEN)-mediated genome editing. For social behavioral tests, we have established a social interaction test, shoaling assay, and group behavior assay. For molecular analysis, we examined the neuronal activity in specific brain regions of dyrk1aa KO zebrafish through in situ hybridization with various probes including c-fos and crh which are the molecular markers for stress response.

RESULTS

Microarray detected an intragenic microdeletion of DYRK1A in an individual with microcephaly and autism. From behavioral tests of social interaction and group behavior, dyrk1aa KO zebrafish exhibited social impairments that reproduce human phenotypes of autism in a vertebrate animal model. Social impairment in dyrk1aa KO zebrafish was further confirmed by molecular analysis of c-fos and crh expression. Transcriptional expression of c-fos and crh was lower than that of wild type fish in specific hypothalamic regions, suggesting that KO fish brains are less activated by social context.

CONCLUSIONS

In this study, we established a zebrafish model to validate a candidate gene for autism in a vertebrate animal. These results illustrate the functional deficiency of DYRK1A as an underlying disease mechanism for autism. We also propose simple social behavioral assays as a tool for the broader study of autism candidate genes.

Properties of excitatory synaptic events in neurons of primary somatosensory cortex of neonatal rats

We have characterized the development of synaptic responses from neurons of rat parietal cortex. Whole-cell recording was used in slice preparations in vitro. Neurons were stained with biocytin to allow their identification, and the sample included pyramidal neurons and Cajal-Retzius cells. Dye-coupling of 3-12 cells was frequently observed from the day of birth (P0) to P3. On average, when recorded with Cs(+)-filled electrodes, the input resistances of neonatal cells were large (mean = 1.1 G omega) and resting membrane potentials were relatively depolarized (mean = -45 mV) when compared to mature neocortical neurons. The application of an NMDA receptor antagonist usually hyperpolarized cells by 5-10 mV and increased their input resistance (mean increase = 83%), suggesting that immature neurons are tonically activated by excitatory amino acids (EAA) in our preparation. Excitatory postsynaptic potentials (EPSPs) or currents (EPSCs) could be obtained from animals as young as P0 by brief stimulation of the subplate. Synaptic responses at these early ages had long durations, often lasting over hundreds of milliseconds, they reversed polarity around 0 mV, and they were blocked by tetrodotoxin and EAA antagonists. Pharmacology and current-voltage relationships demonstrated the presence of both NMDA receptor- and non-NMDA receptor-dependent components in most EPSPs. Unlike synaptic responses of mature neurons, neonatal synaptic responses were composed largely of NMDA receptor-dependent components. We did not observe inhibitory synaptic inputs before P6. In some neurons, single shocks to the subplate region initiated spontaneous EPSPs that lasted > 1 min. This study clearly demonstrates functional synapses in the neocortex of rats on the day of birth. Large NMDA receptor-mediated EPSPs with long duration could have a major influence on the development of cortical circuits in the neonate.