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R W Hendriks

Publications and source records attributed to R W Hendriks.

At least 37 records · Page 2Linked to original sources
PubMed1994

Mutation analysis of the Bruton's tyrosine kinase gene in X-linked agammaglobulinemia: identification of a mutation which affects the same codon as is altered in immunodeficient xid mice.

X-linked agammaglobulinemia (XLA) is an inherited immunodeficiency disease in man, reflecting an arrest in differentiation of pre-B cells to mature B cell stages. The gene defective in XLA has been identified as a cytoplasmic protein tyrosine kinase, named btk (Bruton's tyrosine kinase). Here we report the characterization of mutations in the btk gene of five unrelated XLA families. Amplified products were generated from cDNA, cloned and sequenced. Three single point mutations and two small insertions were identified. One of the point mutations and the two insertions created stop codons that would lead to truncated btk proteins. In one XLA patient we found a single basepair substitution that altered the highly conserved Arg288 within the SH2 domain and would therefore abrogate interactions with substrate phosphotyrosines. In another XLA patient a single basepair substitution was observed that altered the conserved Arg28 residue in the N-terminal unique region of unknown function. This residue is also mutated in the xid mouse, which has a different, less severe, B cell deficiency. We conclude that a similar mutation in the btk gene leads in man to an almost complete arrest at an early stage of B cell differentiation, but in the mouse to only limited B cell abnormalities.

Agammaglobulinaemia Tyrosine Kinase↗
PubMed1994

Absence of the XIST gene from late-replicating isodicentric X chromosomes in leukaemia.

The mechanism of X-inactivation in man is thought to involve a specific cis-acting locus within the X-inactivation centre at Xq13 (1,2). The XIST gene (X inactive specific transcript) at Xq13 is ubiquitously expressed only from the inactive X and as such may be involved in or influenced by the X-inactivation process (3,4). We have localised the breakpoints on two acquired isodicentric X chromosomes associated with leukaemia to a 450 kilobase region of DNA within Xq13, which result in deletion of the XIST gene. We have demonstrated that these chromosomes remain inactive and that there is no evidence of XIST expression from the remaining intact X chromosomes. The data suggest that XIST is not required for the maintenance of X-inactivation on these somatically rearranged X chromosomes.

Anemia, Refractory, with Excess of Blasts↗
PubMed1993

Diversity of immunoglobulin kappa light chain gene rearrangements and evidence for somatic mutation in V kappa IV family gene segments in X-linked agammaglobulinemia.

X-linked agammaglobulinemia (XLA) is a humoral immunodeficiency disease in man, characterized by an arrest in B lymphocyte differentiation at the precursor B cell stage. The structure of expressed immunoglobulin (Ig) kappa light (L) chain rearrangements of nine B lymphoblastoid cell lines from one XLA patient was investigated by amplification of cDNA by the polymerase chain reaction using 5' V kappa family-specific primers and a 3' kappa constant region primer. Members of all four V kappa gene families were found to be utilized in Ig kappa L chain rearrangements at frequencies that were consistent with random V kappa family usage. There was no preference for usage of any particular kappa joining segment. Additional diversity was generated by deletions and random nucleotide insertions at the site of juxtaposition. Particular V kappa members seemed to be overrepresented in the sample. The observed homology of the V kappa I, V kappa II and V kappa III region sequences, both to each other and to known germ-line V kappa sequence indicated the absence of somatic mutations in the majority of these expressed Ig genes. In contrast of the single-member V kappa IV family four different sequences were found to be expressed. That these sequences were mutated derivatives of a germ-line V kappa IV element was substantiated both by sequence analysis and oligonucleotide hybridization. This finding shows that the mutation process can occur in early stages of B cell development i.e. before H chain class switch has occurred. The presence of these mutations is probably independent of clonal expansion since XLA patients are unable to respond to antigen. We conclude that the differentiation arrest in XLA does not preclude early onset of somatic mutation events in V kappa gene segments.

Agammaglobulinemia↗
PubMed1993

The Bruton's tyrosine kinase gene is expressed throughout B cell differentiation, from early precursor B cell stages preceding immunoglobulin gene rearrangement up to mature B cell stages.

X-linked agammaglobulinemia (XLA) is an immunodeficiency disease in man, resulting from an arrest in early B cell differentiation. The gene defective in XLA has recently been identified and encodes a cytoplasmic protein tyrosine kinase, named Bruton's tyrosine kinase (btk), essential for cell differentiation and proliferation at the transition from pre-B to later B cell stages. In this study we investigated btk expression by Northern blotting experiments in a series of human (precursor-) B cell lines, acute lymphoblastic leukemias and plasmacytomas. btk was found to be already expressed in very early stages of B cell differentiation, even prior to immunoglobulin (Ig) heavy (H) or light (L) chain gene rearrangements. Transcripts were also detected at the pre-B cell stage and in mature B cells, irrespective of the Ig H chain class expressed. Approximately at the transition from mature B cells to plasma cells, expression of the btk gene is down-regulated. In addition, the btk gene was found to be expressed in myeloid cell lines and acute myeloid leukemias. btk expression in myeloid cells is probably not a prerequisite for myeloid differentiation, since myeloid cells in XLA patients seem not to be affected. No btk expression was found in T-lineage cells. The btk expression profile, i.e. from early precursor-B cell stages preceding Ig rearrangement up to mature B cells, supports the hypothesis that the XLA defect resides in a critical step of B cell development which is independent of the Ig gene recombination machinery.

Agammaglobulinemia↗
PubMed1993

Norrie disease gene: characterization of deletions and possible function.

Positional cloning experiments have resulted recently in the isolation of a candidate gene for Norrie disease (pseudoglioma; NDP), a severe X-linked neurodevelopmental disorder. Here we report the isolation and analysis of human genomic DNA clones encompassing the NDP gene. The gene spans 28 kb and consists of 3 exons, the first of which is entirely contained within the 5' untranslated region. Detailed analysis of genomic deletions in Norrie patients shows that they are heterogeneous, both in size and in position. By PCR analysis, we found that expression of the NDP gene was not confined to the eye or to the brain. An extensive DNA and protein sequence comparison between the human NDP gene and related genes from the database revealed homology with cysteine-rich protein-binding domains of immediate--early genes implicated in the regulation of cell proliferation. We propose that NDP is a molecule related in function to these genes and may be involved in a pathway that regulates neural cell differentiation and proliferation.

Amino Acid Sequence↗
PubMed1993

Mapping of the X linked form of hyper IgM syndrome (HIGM1)

X linked immunodeficiency with hyperimmunoglobulinaemia M (HIGM1), which is characterised by agammaglobulinaemia together with excess IgM production reflecting an impairment of the immunoglobulin heavy chain class switch of B lymphocytes, has been mapped to Xq26. We report multipoint linkage data in six families with HIGM1 which show that the most likely position for the gene is close to HPRT with a maximum lod score of 4.89. The finding of recombinations between HIGM1 and both HPRT and DXS42 implies that HIGM1 is not allelic to X linked lymphoproliferative disease. These data will be useful in genetic counselling in families and will also be useful in testing candidate genes.

Base Sequence↗
PubMed1993

Carrier detection in X-linked immunodeficiencies. II: An X inactivation assay based on differential methylation of a line-1 repeat at the DXS255 locus.

The differential methylation of a CpG island 2.5 kb distant from a hypervariable region at the DXS255 locus provides the basis for a Southern blotting X chromosome inactivation analysis system. The technique enables carrier detection in about 90% of females at risk from pedigrees with Wiskott-Aldrich syndrome, X-linked severe combined immunodeficiency or X-linked agammaglobulinemia.

Agammaglobulinemia↗
PubMed1992

Immunoglobulin kappa light chain germ-line transcripts in human precursor B lymphocytes.

B lymphoblastoid cell lines (BLCL), established from bone marrow and peripheral blood mononuclear cells from two severe combined immunodeficiency (SCID) patients, manifested a complete absence of genomic rearrangements of the immunoglobulin (Ig) heavy (H) and light (L) chain loci. The BLCL contained germ-line transcripts of the Ig kappa region locus of approximately 1.2 kilobase (kb). By cDNA cloning and sequence analysis the transcripts were shown to consist of a C kappa segment, a J kappa 1 gene segment, 160 base pairs (bp) of J kappa 1 5' intervening sequence, containing the heptamer/nonamer recombination recognition sequences and at the 5' end a 523-bp segment designated human kappa zero, The first 206 bp of this 5' segment were homologous to the reported murine kappa zero region. Genomic restriction mapping and DNA sequence analysis demonstrated that the human kappa zero segment is located approximately 4 kb upstream of J kappa 1. The kappa zero segment contains a putative promoter region with an OCT2 binding site, and has a splice donor site to accomplish splicing to an acceptor site 160 bp upstream of J kappa 1. Expression of the kappa zero gene segment was found in BLCL derived from normal fetal bone marrow, in which both Ig kappa loci were in the germ-line configuration. These findings indicate that the described transcripts are not only present in SCID, but also in normal developing pre-B lymphocytes. The expression of germ-line Ig kappa L chain transcripts may be associated with the locus becoming accessible to gene rearrangement.

B-Lymphocytes↗
PubMed1992

Characterization of a highly polymorphic region near the first exon of the human MAOA gene containing a GT dinucleotide and a novel VNTR motif.

The genes encoding the A and B forms of the human monoamine oxidase enzymes (MAOA and MAOB) are localized at Xp11.23-Xp11.4. We report the characterization of a highly informative polymorphic region within a 2.9-kb cloned fragment containing the first exon of the MAOA gene. The polymorphic region consists of a GT microsatellite directly adjacent to an imperfectly duplicated novel 23-bp VNTR motif. DNA sequencing within and flanking the repeated segment allowed the design of specific amplification primers. In 56 unrelated females, 15 different alleles were identified with sizes ranging from 285 to 388 bp. The alleles differed in both the number of dinucleotide and the number of VNTR repeats, yielding a highly informative polymorphic marker locus with a calculated heterozygosity value of 75%.

Alleles↗
PubMed1992

The hypervariable DXS255 locus contains a LINE-1 repetitive element with a CpG island that is extensively methylated only on the active X chromosome.

The DXS255 locus at Xp11.22 is highly polymorphic due to a 26-bp variable number of tandem repeats (VNTR) motif. In previous studies, one of the MspI sites flanking the VNTR manifested a correlation between methylation and X chromosome inactivation. Here we show, by DNA sequence analysis, that this MspI site is located within the CpG island at the 5' end of a LINE-1 element, which is 2.5 kb from the VNTR. The methylation status of the CpG island was assessed in Southern blotting experiments using the methylation-sensitive enzymes HpaII, HhaI, and BssHII. All these sites were completely methylated on active X chromosomes, consistent with previously reported findings of full methylation of LINE-1 elements throughout the genome. However, on inactive X chromosomes these sites were predominantly unmethylated, although patterns were found to be heterogeneous. The results suggest that LINE-1 elements on the inactive X chromosome are not suppressed by full methylation of their CpG islands. The differential methylation of the DXS255 CpG island provides the basis for a highly informative X inactivation analysis system.

Base Sequence↗
PubMed1992

Isolation and characterization of a candidate gene for Norrie disease.

Previous analysis has refined the location of the gene for Norrie disease, a severe, X-linked, recessive neurodevelopmental disorder, to a yeast artificial chromosome subfragment of 160 kilobases (kb). This fragment was used to screen cDNA libraries from human fetal and adult retina. As a result, we have identified an evolutionarily conserved cDNA, which is expressed in fetal and adult brain and encodes a predicted protein of 133 amino acids. The cDNA detects genomic sequences which span a maximum of 50 kb, and which are partly deleted in several typical Norrie disease patients. An EcoRI polymorphism with a calculated heterozygosity value of 43% was observed. The locus identified is a strong candidate for the Norrie disease gene.

Amino Acid Sequence↗
PubMed1992

An X chromosome inactivation assay based on differential methylation of a CpG island coupled to a VNTR polymorphism at the 5' end of the monoamine oxidase A gene.

A CpG island has been identified just upstream of the first exon of the human monoamine oxidase A (MAOA) gene, localized to Xp11.4-Xp11.23. Southern blotting following digestion with the methylation sensitive restriction endonucleases SmaI, HpaII and HhaI, indicated that CpG dinucleotides within the CpG island were unmethylated on the active X chromosome and extensively methylated on the inactive X chromosome. These sites of differential methylation were close to a polymorphic GT-dinucleotide/VNTR region, which is located 1 kb 3' of the first exon and has a heterozygosity value of 75%. PCR primers were designed for amplification of 1.2-1.3 kb DNA fragments, encompassing both the hypervariable region and a cluster of six HpaII sites within the CpG-rich region. Cleavage of HpaII sites was found to be restricted to active X chromosomes. Therefore, following HpaII digestion, DNA fragments were exclusively amplified from inactive X chromosomes. The resulting PCR products were digested with SacI, which reduced the size of the DNA fragments containing the hypervariable region to 230-330 bp, and were subsequently analyzed on denaturating polyacrylamide gels. Because amplified fragments were exclusively derived from the inactive X chromosome, the relative densities of the two allelic fragments should reflect the proportions of cells that have either of the two X chromosome inactivated. The results of this PCR-based X chromosome inactivation assay were fully concordant with Southern blotting methylation analyses at the PGK locus. It therefore provides a rapid and informative method in tumour clonality analysis and carrier detection in X-linked diseases.

Base Sequence↗
PubMed1992

X chromosome inactivation patterns in haematopoietic cells of female carriers of X-linked severe combined immunodeficiency determined by methylation analysis at the hypervariable DXS255 locus.

The patterns of X chromosome inactivation were determined in 14 females from three unrelated X-linked severe combined immunodeficiency (XSCID) pedigrees. All the females were found to be heterozygous for the hypervariable DXS255 locus, enabling analysis of differential methylation of this locus in peripheral blood haematopoietic cells. All six obligate carriers manifested a unilateral X chromosome inactivation in the T lymphocyte population. Differential methylation analysis of T lymphocytes was subsequently applied to establish the carrier status of females at risk in the XSCID pedigrees. In the B lymphocyte population of four XSCID carriers a unilateral X chromosome inactivation was observed. Four other carriers had minor fractions and one carrier had a substantial fraction of B lymphocytes with the XSCID gene defect on the active X chromosome. Within single XSCID pedigrees the carriers manifested different patterns. In two pedigrees the granulocyte populations of all carriers showed a random distribution of X chromosome inactivation. In the third pedigree the granulocytes of the three carriers analyzed manifested complete inactivation of the X chromosome that carried the XSCID mutation, exposing a selective disadvantage of granulocytes that express the XSCID defect. The pedigree-dependent differences in the involvement of the granulocyte population suggest the existence of two distinct XSCID defects.

Blotting, Southern↗