Isolation and characterization of a human novel RAB (RAB39B) gene

Loss of RAB39B does not alter MPTP-induced Parkinson's disease-like phenotypes in mice

Parkinson's disease (PD) is a common neurodegenerative movement disorder with undetermined etiology. A major pathological hallmark of PD is the progressive degeneration of dopaminergic neurons in the substantia nigra. Loss-of-function mutations in the RAB39B gene, which encodes a neuronal-specific small GTPase RAB39B, have been associated with X-linked intellectual disability and pathologically confirmed early-onset PD in multiple families. However, the role of RAB39B in PD pathogenesis remains elusive. In this study, we treated Rab39b knock-out (KO) mice with MPTP to explore whether RAB39B deficiency could alter MPTP-induced behavioral impairments and dopaminergic neuron degeneration. Surprisingly, we found that MPTP treatment impaired motor activity and led to loss of tyrosine hydroxylase-positive dopaminergic neurons and gliosis in both WT and Rab39b KO mice. However, RAB39B deficiency did not alter MPTP-induced impairments. These results suggest that RAB39B deficiency does not contribute to PD-like phenotypes through compromising dopaminergic neurons in mice; and its role in PD requires further scrutiny.

RAB39B as a Chemosensitivity-Related Biomarker for Diffuse Large B-Cell Lymphoma

Background: Diffuse large B-cell lymphoma (DLBCL) is the most common aggressive lymphoma with an increased tendency to relapse or refractoriness. RAB39B, a member of the Ras-oncogene superfamily, is associated with a variety of tumors. Nevertheless, the role of RAB39B in DLBCL is still unknown. This study aimed to identify the role of RAB39B in DLBCL using integrated bioinformatics analysis.

Methods: RAB39B expression data were examined using TIMER, UCSC, and GEO databases. The LinkedOmics database was used to study the genes and signaling pathways related to RAB39B expression. A Protein–protein interaction network was performed in STRING. TIMER was used to analyze the correlation between RAB39B and infiltrating immune cells. The correlation between RAB39B and m6A-related genes in DLBCL was analyzed using TCGA data. The RAB39B ceRNA network was constructed based on starBase and miRNet2.0 databases. Drug sensitivity information was obtained from the GSCA database.

Results: RAB39B was highly expressed in multiple tumors including DLBCL. The protein–protein interaction network showed enrichment of autophagy and RAS family proteins. Functional enrichment analysis of RAB39B co-expression genes revealed that RAB39B was closely related to DNA replication, protein synthesis, cytokine–cytokine receptor interaction, JAK-STAT signaling pathway, NF-kappa B signaling pathway, and autophagy. Immune infiltrate analysis showed that the amount of RAB39B was negatively correlated with iDC, Tem, and CD8 T-cell infiltration. CD4⁺ T cell and DC were negatively correlated with CNV of RAB39B. DLBCL cohort analysis found that RAB39B expression was related to 14 m6A modifier genes, including YTHDC1, YTHDC2, YTHDF1, YTHDF2, YTHDF3, RBMX, ZC3H13, METTL14, METTL3, RBM15, RBM15B, VIRMA, FTO, and ALKBH5. We constructed 14 possible ceRNA networks of RAB39B in DLBCL. The RAB39B expression was associated with decreased sensitivity of chemotherapy drugs such as dexamethasone, doxorubicin, etoposide, vincristine, and cytarabine and poor overall survival in DLBCL. In vitro experiments showed that RAB39B was associated with proliferation, apoptosis, and drug sensitivity of DLBCL cells.

Conclusion: RAB39B is abnormally elevated and related to drug resistance and poor OS in DLBCL, which may be due to its involvement in immune infiltration, m6A modification, and regulation by multiple non-coding RNAs. RAB39B may be used as an effective biomarker for the diagnosis and treatment of DLBCL.

CRISPR-Cas9-Based Technology and Its Relevance to Gene Editing in Parkinson's Disease

Parkinson’s disease (PD) and other chronic and debilitating neurodegenerative diseases (NDs) impose a substantial medical, emotional, and financial burden on individuals and society. The origin of PD is unknown due to a complex combination of hereditary and environmental risk factors. However, over the last several decades, a significant amount of available data from clinical and experimental studies has implicated neuroinflammation, oxidative stress, dysregulated protein degradation, and mitochondrial dysfunction as the primary causes of PD neurodegeneration. The new gene-editing techniques hold great promise for research and therapy of NDs, such as PD, for which there are currently no effective disease-modifying treatments. As a result, gene therapy may offer new treatment options, transforming our ability to treat this disease. We present a detailed overview of novel gene-editing delivery vehicles, which is essential for their successful implementation in both cutting-edge research and prospective therapeutics. Moreover, we review the most recent advancements in CRISPR-based applications and gene therapies for a better understanding of treating PD. We explore the benefits and drawbacks of using them for a range of gene-editing applications in the brain, emphasizing some fascinating possibilities.

Clustered regularly interspaced short palindromic repeats as an advanced treatment for Parkinson's disease

Recently, genome-editing technology like clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 has improved the translational gap in the treatments mediated through gene therapy. The advantages of the CRISPR system, such as, work in the living cells and tissues, candidate this technique for the employing in experiments and the therapy of central nervous system diseases. Parkinson's disease (PD) is a widespread, disabling, neurodegenerative disease induced by dopaminergic neuron loss and linked to progressive motor impairment. Pathophysiological basis knowledge of PD has modified the PD classification model and expresses in the sporadic and familial types. Analyses of the earliest genetic linkage have shown in PD the inclusion of synuclein alpha (SNCA) genomic duplication and SNCA mutations in the familial types of PD pathogenesis. This review analyzes the structure, development, and function in genome editing regulated through the CRISPR/Cas9. Also, it explains the genes associated with PD pathogenesis and the appropriate modifications to favor PD. This study follows the direction by understanding the PD linking analyses in which the CRISPR technique is applied. Finally, this study explains the limitations and future trends of CRISPR service in relation to the genome-editing process in PD patients' induced pluripotent stem cells.

Dysfunction of RAB39B-Mediated Vesicular Trafficking in Lewy Body Diseases

Intracellular vesicular trafficking is essential for neuronal development, function, and homeostasis and serves to process, direct, and sort proteins, lipids, and other cargo throughout the cell. This intricate system of membrane trafficking between different compartments is tightly orchestrated by Ras analog in brain (RAB) GTPases and their effectors. Of the 66 members of the RAB family in humans, many have been implicated in neurodegenerative diseases and impairment of their functions contributes to cellular stress, protein aggregation, and death. Critically, RAB39B loss-of-function mutations are known to be associated with X-linked intellectual disability and with rare early-onset Parkinson's disease. Moreover, recent studies have highlighted altered RAB39B expression in idiopathic cases of several Lewy body diseases (LBDs). This review contextualizes the role of RAB proteins in LBDs and highlights the consequences of RAB39B impairment in terms of endosomal trafficking, neurite outgrowth, synaptic maturation, autophagy, as well as alpha-synuclein homeostasis. Additionally, the potential for therapeutic intervention is examined via a discussion of the recent progress towards the development of specific RAB modulators. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

RAB39B Deficiency Impairs Learning and Memory Partially Through Compromising Autophagy

RAB39B is located on the X chromosome and encodes the RAB39B protein that belongs to the RAB family. Mutations in RAB39B are known to be associated with X-linked intellectual disability (XLID), Parkinson’s disease, and autism. However, the patho/physiological functions of RAB39B remain largely unknown. In the present study, we established Rab39b knockout (KO) mice, which exhibited overall normal birth rate and morphologies as wild type mice. However, Rab39b deficiency led to reduced anxiety and impaired learning and memory in 2 months old mice. Deletion of Rab39b resulted in impairments of synaptic structures and functions, with reductions in NMDA receptors in the postsynaptic density (PSD). RAB39B deficiency also compromised autophagic flux at basal level, which could be overridden by rapamycin-induced autophagy activation. Further, treatment with rapamycin partially rescued impaired memory and synaptic plasticity in Rab39b KO mice, without affecting the PSD distribution of NMDA receptors. Together, these results suggest that RAB39B plays an important role in regulating both autophagy and synapse formation, and that targeting autophagy may have potential for treating XLID caused by RAB39B loss-of-function mutations.

RAB39B's role in membrane traffic, autophagy, and associated neuropathology

Neuropathological disorders are increasingly associated with dysfunctions in neuronal membrane traffic and autophagy, with defects among members of the Rab family of small GTPases implicated. Mutations in the human Xq28 localized gene RAB39B have been associated with X-linked neurodevelopmental defects including macrocephaly, intellectual disability, autism spectrum disorder (ASD), as well as rare cases of early-onset Parkinson's disease (PD). Despite the finding that RAB39B regulates GluA2 trafficking and could thus influence synaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor subunit composition, reasons for the wide-ranging neuropathological consequences associated with RAB39B defects have been unclear. Recent studies have now unraveled possible mechanisms underlying the neuropathological roles of this brain-enriched small GTPase. Studies in RAB39B knockout mice showed that RAB39B interacts with components of Class I phosphatidylinositol-3-kinase (PI3K) signaling. In its absence, the PI3K-AKT-mechanistic target of rapamycin signaling pathway in neural progenitor cells (NPCs) is hyperactivated, which promotes NPC proliferation, leading to macrocephaly and ASD. Pertaining to early-onset PD, a complex of C9orf72, Smith-Magenis syndrome chromosome region candidate 8 and WD repeat domain 41 that functions in autophagy has been identified as a guanine nucleotide exchange factor of RAB39B. Here, recent findings that have shed light on our mechanistic understanding of RAB39B's role in neurodevelopmental and neurodegenerative pathologies are reviewed. Caveats and unanswered questions are also discussed, and future perspectives outlined.

CRISPR System: A High-throughput Toolbox for Research and Treatment of Parkinson's Disease

In recent years, the innovation of gene-editing tools such as the CRISPR/Cas9 system improves the translational gap of treatments mediated by gene therapy. The privileges of CRISPR/Cas9 such as working in living cells and organs candidate this technology for using in research and treatment of the central nervous system (CNS) disorders. Parkinson's disease (PD) is a common, debilitating, neurodegenerative disorder which occurs due to loss of dopaminergic neurons and is associated with progressive motor dysfunction. Knowledge about the pathophysiological basis of PD has altered the classification system of PD, which manifests in familial and sporadic forms. The first genetic linkage studies in PD demonstrated the involvement of Synuclein alpha (SNCA) mutations and SNCA genomic duplications in the pathogenesis of PD familial forms. Subsequent studies have also insinuated mutations in leucine repeat kinase-2 (LRRK2), Parkin, PTEN-induced putative kinase 1 (PINK1), as well as DJ-1 causing familial forms of PD. This review will attempt to discuss the structure, function, and development in genome editing mediated by CRISP/Cas9 system. Further, it describes the genes involved in the pathogenesis of PD and the pertinent alterations to them. We will pursue this line by delineating the PD linkage studies in which CRISPR system was employed. Finally, we will discuss the pros and cons of CRISPR employment vis-à-vis the process of genome editing in PD patients' iPSCs.

Rab39a and Rab39b Display Different Intracellular Distribution and Function in Sphingolipids and Phospholipids Transport

Rab GTPases define the identity and destiny of vesicles. Some of these small GTPases present isoforms that are expressed differentially along developmental stages or in a tissue-specific manner, hence comparative analysis is difficult to achieve. Here, we describe the intracellular distribution and function in lipid transport of the poorly characterized Rab39 isoforms using typical cell biology experimental tools and new ones developed in our laboratory. We show that, despite their amino acid sequence similarity, Rab39a and Rab39b display non-overlapping intracellular distribution. Rab39a localizes in the late endocytic pathway, mainly at multivesicular bodies. In contrast, Rab39b distributes in the secretory network, at the endoplasmic reticulum/cis-Golgi interface. Therefore, Rab39a controls trafficking of lipids (sphingomyelin and phospholipids) segregated at multivesicular bodies, whereas Rab39b transports sphingolipids biosynthesized at the endoplasmic reticulum-Golgi factory. Interestingly, lyso bis-phosphatidic acid is exclusively transported by Rab39a, indicating that both isoforms do not exert identical functions in lipid transport. Conveniently, the requirement of eukaryotic lipids by the intracellular pathogen Chlamydia trachomatis rendered useful for dissecting and distinguishing Rab39a- and Rab39b-controlled trafficking pathways. Our findings provide comparative insights about the different subcellular distribution and function in lipid transport of the two Rab39 isoforms.

Sex Differences in Autophagy Contribute to Female Vulnerability in Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia, with over 5. 4 million cases in the US alone (Alzheimer's Association, 2016). Clinically, AD is defined by the presence of plaques composed of Aβ and neurofibrillary pathology composed of the microtubule associated protein tau. Another key feature is the dysregulation of autophagy at key steps in the pathway. In AD, disrupted autophagy contributes to disease progression through the failure to clear pathological protein aggregates, insulin resistance, and its role in the synthesis of Aβ. Like many psychiatric and neurodegenerative diseases, the risk of developing AD, and disease course are dependent on the sex of the patient. One potential mechanism through which these differences occur, is the effects of sex hormones on autophagy. In women, the loss of hormones with menopause presents both a risk factor for developing AD, and an obvious example of where sex differences in AD can stem from. However, because AD pathology can begin decades before menopause, this does not provide the full answer. We propose that sex-based differences in autophagy regulation during the lifespan contribute to the increased risk of AD, and greater severity of pathology seen in women.

Consequences of Rab GTPase dysfunction in genetic or acquired human diseases

Rab GTPases are important regulators of intracellular membrane trafficking in eukaryotes. Both activating and inactivating mutations in Rab genes have been identified and implicated in human diseases ranging from neurological disorders to cancer. In addition, altered Rab expression is often associated with disease prognosis. As such, the study of diseases associated with Rabs or Rab-interacting proteins has shed light on the important role of intracellular membrane trafficking in disease etiology. In this review, we cover recent advances in the field with an emphasis on cellular mechanisms.

A novel RAB39B gene mutation in X-linked juvenile parkinsonism with basal ganglia calcification

OBJECTIVES

Mutations in RAB39B have been reported as a potential cause of X-linked Parkinson's disease (PD), a rare form of familial PD. We conducted a genetic analysis on RAB39B to evaluate whether RAB39B mutations are related to PD in the Chinese population.

METHODS

In this study, 2 patients from an X-linked juvenile parkinsonism pedigree were clinically characterized and underwent whole-exome sequencing. A comprehensive screening for RAB39B mutations in 505 sporadic patients with PD and 510 healthy controls in a Chinese population was also performed.

RESULTS

A novel mutation, c. 536dupA (p.E179fsX48), in RAB39B was identified in the juvenile parkinsonism pedigree. Brain MRI and CT scans in the 2 patients revealed calcification within the bilateral globus pallidus. No other potentially disease-causing RAB39B mutations were found in sporadic PD patients and controls.

CONCLUSIONS

X-linked juvenile parkinsonism could be caused by a RAB39B mutation, and basal ganglia calcification may be a novel clinical feature of RAB39B-related parkinsonism. © 2016 International Parkinson and Movement Disorder Society.

Consequences of Rab GTPase dysfunction in genetic or acquired human diseases

Rab GTPases are important regulators of intracellular membrane trafficking in eukaryotes. Both activating and inactivating mutations in Rab genes have been identified and implicated in human diseases ranging from neurological disorders to cancer. In addition, altered Rab expression is often associated with disease prognosis. As such, the study of diseases associated with Rabs or Rab-interacting proteins has shed light on the important role of intracellular membrane trafficking in disease etiology. In this review, we cover recent advances in the field with an emphasis on cellular mechanisms.

Rab GTPases: The Key Players in the Molecular Pathway of Parkinson's Disease

Parkinson’s disease (PD) is a progressive movement disorder with multiple non-motor symptoms. Although family genetic mutations only account for a small proportion of the cases, these mutations have provided several lines of evidence for the pathogenesis of PD, such as mitochondrial dysfunction, protein misfolding and aggregation, and the impaired autophagy-lysosome system. Recently, vesicle trafficking defect has emerged as a potential pathogenesis underlying this disease. Rab GTPases, serving as the core regulators of cellular membrane dynamics, may play an important role in the molecular pathway of PD through the complex interplay with numerous factors and PD-related genes. This might shed new light on the potential therapeutic strategies. In this review, we emphasize the important role of Rab GTPases in vesicle trafficking and summarize the interactions between Rab GTPases and different PD-related genes.

RAB39B gene mutations are not linked to familial Parkinson's disease in China

Recently, RAB39B mutations were reported to be a causative factor in patients with Parkinson's disease (PD). To validate the role of RAB39B in familial PD, a total of 195 subjects consisting of 108 PD families with autosomal-dominant (AD) inheritance and 87 PD families with autosomal-recessive (AR) inheritance in the Chinese Han population from mainland China were included in this study. We did not identify any variants in the coding region or the exon-intron boundaries of the gene by Sanger sequencing method in the DNA samples of 180 patients (100 with AD and 80 with AR). Furthermore, we did not find any variants in the RAB39B gene when Whole-exome sequencing (WES) was applied to DNA samples from 15 patients (8 with AD and 7 with AR) for further genetic analysis. Additionally, when quantitative real-time PCR was used to exclude large rearrangement variants in these patients, we found no dosage mutations in RAB39B gene. Our results suggest that RAB39B mutation is very rare in familial PD and may not be a major cause of familial PD in the Chinese Han Population.

Loss-of-function mutations in RAB39B are associated with typical early-onset Parkinson disease

Rab proteins are small molecular weight guanosine triphosphatases involved in the regulation of vesicular trafficking.(1) Three of 4 X-linked RAB genes are specific to the brain, including RAB39B. Recently, Wilson et al.(2) reported that mutations in RAB39B cause X-linked intellectual disability (ID) and pathologically confirmed Parkinson disease (PD). They identified a ∼45-kb deletion resulting in the complete loss of RAB39B in an Australian kindred and a missense mutation in a large Wisconsin kindred. Here, we report an additional affected man with typical PD and mild mental retardation harboring a new truncating mutation in RAB39B.

Probing the virus host interaction in high containment: an approach using pooled short hairpin RNA

The study of viruses in high containment offers unique challenges for technology-intense approaches. These approaches include high-throughput screening for small-molecule antivirals and genetic perturbation-based screens for host factors required for viral replication. Here, we describe the use of whole-genome scale pooled short hairpin RNA (shRNA) libraries to screen for host factors necessary for viral infection at BSL2, and the transition of this technique into the BSL4 environment. Pooled screening provides a unique way to circumvent many of the technological challenges associated with other high-throughput screening approaches in high containment. Our pooled screening approach identified host factors involved in the replication of orthopoxviruses (Vaccinia and Monkeypox) and filoviruses (Ebola and Marburg) under conditions that enable straightforward screen-to-follow-up approaches.

Mutations in RAB39B cause X-linked intellectual disability and early-onset Parkinson disease with α-synuclein pathology

Advances in understanding the etiology of Parkinson disease have been driven by the identification of causative mutations in families. Genetic analysis of an Australian family with three males displaying clinical features of early-onset parkinsonism and intellectual disability identified a ∼45 kb deletion resulting in the complete loss of RAB39B. We subsequently identified a missense mutation (c.503C>A [p.Thr168Lys]) in RAB39B in an unrelated Wisconsin kindred affected by a similar clinical phenotype. In silico and in vitro studies demonstrated that the mutation destabilized the protein, consistent with loss of function. In vitro small-hairpin-RNA-mediated knockdown of Rab39b resulted in a reduction in the density of α-synuclein immunoreactive puncta in dendritic processes of cultured neurons. In addition, in multiple cell models, we demonstrated that knockdown of Rab39b was associated with reduced steady-state levels of α-synuclein. Post mortem studies demonstrated that loss of RAB39B resulted in pathologically confirmed Parkinson disease. There was extensive dopaminergic neuron loss in the substantia nigra and widespread classic Lewy body pathology. Additional pathological features included cortical Lewy bodies, brain iron accumulation, tau immunoreactivity, and axonal spheroids. Overall, we have shown that loss-of-function mutations in RAB39B cause intellectual disability and pathologically confirmed early-onset Parkinson disease. The loss of RAB39B results in dysregulation of α-synuclein homeostasis and a spectrum of neuropathological features that implicate RAB39B in the pathogenesis of Parkinson disease and potentially other neurodegenerative disorders.

Human diseases associated with form and function of the Golgi complex

The Golgi complex lies at the heart of the secretory pathway and is responsible for modifying proteins and lipids, as well as sorting newly synthesized molecules to their correct destination. As a consequence of these important roles, any changes in its proteome can negatively affect its function and in turn lead to disease. Recently, a number of proteins have been identified, which when either depleted or mutated, result in diseases that affect various organ systems. Here we describe how these proteins have been linked to the Golgi complex, and specifically how they affect either the morphology, membrane traffic or glycosylation ability of this organelle.

DENN domain proteins: regulators of Rab GTPases

The DENN domain is a common, evolutionarily ancient, and conserved protein module, yet it has gone largely unstudied; until recently, little was known regarding its functional roles. New studies reveal that various DENN domains interact directly with members of the Rab family of small GTPases and that DENN domains function enzymatically as Rab-specific guanine nucleotide exchange factors. Thus, DENN domain proteins appear to be generalized regulators of Rab function. Study of these proteins will provide new insights into Rab-mediated membrane trafficking pathways.

A proteomics approach to decipher the molecular nature of planarian stem cells

Background

In recent years, planaria have emerged as an important model system for research into stem cells and regeneration. Attention is focused on their unique stem cells, the neoblasts, which can differentiate into any cell type present in the adult organism. Sequencing of the Schmidtea mediterranea genome and some expressed sequence tag projects have generated extensive data on the genetic profile of these cells. However, little information is available on their protein dynamics.

Results

We developed a proteomic strategy to identify neoblast-specific proteins. Here we describe the method and discuss the results in comparison to the genomic high-throughput analyses carried out in planaria and to proteomic studies using other stem cell systems. We also show functional data for some of the candidate genes selected in our proteomic approach.

Conclusions

We have developed an accurate and reliable mass-spectra-based proteomics approach to complement previous genomic studies and to further achieve a more accurate understanding and description of the molecular and cellular processes related to the neoblasts.

Rab39a binds caspase-1 and is required for caspase-1-dependent interleukin-1beta secretion

Interleukin-1β (IL-1β) is an important pro-inflammatory cytokine that is secreted by unconventional means in a caspase-1-dependent manner. Using a one-step immunoprecipitation approach to isolate endogenous caspase-1 from the monocytic THP1 cell line, we identified previously undescribed binding partners using mass spectrometry. One of the proteins identified was Rab39a, a member of the Rab GTPase family, a group of proteins that have important roles in protein trafficking and secretion. We confirmed by co-immunoprecipitation that Rab39a binds caspase-1. Knock down of Rab39a with small interfering RNA resulted in diminished levels of secreted IL-1β but had no effect on induction of pro-IL-1β mRNA by lipopolysaccharide. Rab39a contains a highly conserved caspase-1 cleavage site and was cleaved in the presence of recombinant caspase-1 or lipopolysaccharide. Finally, overexpression of Rab39a results in an increase in IL-1β secretion, and furthermore, overexpression of a Rab39a construct lacking the caspase-1 cleavage site leads to an additional increase in IL-1β secretion. Altogether, our findings show that Rab39a interacts with caspase-1 and suggest that Rab39a functions as a trafficking adaptor linking caspase-1 to IL-1β secretion.

Int22h-related inversions causing hemophilia A: a novel insight into their origin and a new more discriminant PCR test for their detection

BACKGROUND

Intrachromosomal, homologous recombination of the duplicon int22h-1 with int22h-2 or int22h-3 causes inversions accounting for 45% of severe hemophilia A, hence the belief that int22h-2 and int22h-3 are in opposite orientation to int22h-1. However, inversions involving int22h-2 are five times rarer than those involving its virtually identical copy: int22h-3. Recent sequencing has indicated that int22h-2 and int22h-3 form the internal part of the arms of an imperfect palindrome so that int22h-2, in the centromeric arm, has the same orientation as int22h-1 and, upon recombination with int22h-1, should produce deletions and duplications but not inversions.

AIM

This work aims to provide rapid tests for all the mutations that can result from recombinations between the int22h sequences and to investigate whether int22h-2-related inversions causing hemophilia A arise in chromosomes, where the arms of the palindrome have recombined so that int22h-2 and int22h-3 swap places and orientation.

PATIENTS/METHODS

Twenty patients with int22h-related inversions were examined together with a control and inversion carriers using reverse transcription-polymerase chain reaction (RT-PCR), long-range PCR and sequencing.

RESULTS AND CONCLUSIONS

Analysis of mRNA in patients and a control provided evidence confirming the palindromic arrangement of int22h-2 and int22h-3 and the proposed inversion polymorphism that allows int22h-2 to be in the telomeric arm of the palindrome and in opposite orientation to int22h-1. New long-range PCR reactions were used to develop a single tube test that detects and discriminates inversions involving int22h-2 or int22h-3 and a two-tube test that can distinguish inversions, deletions, and duplications due to recombination between int22h sequences.

Recurrent duplication of Xq27∼qter in hematological malignancies revealed by multicolor fluorescence in situ hybridization and multicolor banding

Multicolor fluorescence in situ hybridization (M-FISH) experiments were performed to determine the composition of abnormal complex karyotypes in 15 cases of hematological malignancy. Four cases were found to have unsuspected unbalanced X chromosome translocations, which resulted in the presence of extra X chromosome material. We determined the identity of the duplicated chromosome regions using the multicolor banding (mBAND) technique. Xq27-qter was duplicated in three of the four male cases with an X chromosome abnormality (i.e., in one third of male cases and one fifth of all cases). These preliminary results may point to the existence of a recurrent chromosome abnormality, either translocation at a specific Xq27 locus or duplication of Xq27-qter.