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Biomedical subjects

J C Oosterwijk

Publications and source records attributed to J C Oosterwijk.

At least 55 records · Page 3Linked to original sources
PubMed1996

First experiences with genetic counselling based on predictive DNA diagnosis in hereditary glomus tumours (paragangliomas).

Hereditary glomus tumour (MIM 168,000) or paraganglioma (PGL) is a slowly progressive disorder causing benign tumour growth predominantly in the head and neck region. Though benign in nature the tumours can lead to severe morbidity. Inheritance of PGL is autosomal dominant and is strongly modified by genomic imprinting; only a paternally transmitted PGL gene leads to symptoms. A gene for PGL has recently been mapped to 11q22.3-q23. Genetic counselling on the basis of DNA linkage diagnosis was offered in an extended Dutch pedigree. Thirty-two subjects opted for further counselling, of whom 20 applied for DNA testing and participated in a standardised protocol. Sixteen cases had presymptomatic testing (paternal allele); four of these appeared to have the at risk haplotype and in two of them a glomus tumour was subsequently detected on MRI. In one case linkage results were inconclusive (recombination) and one person did not want to learn his test result. Four cases had testing for carrier status (maternal allele) of which one appeared to be a carrier. Our data show that genetic counselling gains significant accuracy when based on parent of origin, sex of the counsellee, and DNA linkage diagnosis. Moreover, a normal DNA result may prevent unnecessary worry and investigations, while an established presymptomatic diagnosis will guide adequate clinical management. The psychological impact of counselling and predictive DNA testing is unclear as yet. Further investigations into the natural history of PGL in gene carriers and into the psychological impact of DNA testing is desirable.

DNA, Neoplasm↗
PubMed1996

An Xp22.1-p22.2 YAC contig encompassing the disease loci for RS, KFSD, CLS, HYP and RP15: refined localization of RS.

To facilitate the positional cloning of the genes involved in retinoschisis (RS), keratosis follicularis spinulosa decalvans (KFSD), Coffin-Lowry syndrome (CLS), X-linked hypophosphatemic rickets (XLH, locus name HYP) and X-linked dominant cone-rod degeneration (locus name RP15), we have extended the molecular map of the Xp22 region. Screening of several YAC libraries allowed us to identify 156 YACs, 52 of which localize between markers DXS414 (P90) and DXS451 (kQST80H1). Analysis of their marker content facilitated the construction of a YAC contig from the region spanning (in this order): DXS414 - DXS987 - DXS207 - DXS1053 - DXS197 - DXS 43 - DXS1195 - DXS418 - DXS999 - PDHA1 - DXS7161 - DXS443 - DXS 7592 - DXS1229 - DXS365 - DXS7101 - DXS7593 - DXS1052 - DXS274 - DXS989 - DXS451. The region between DXS414 and DXS451 covers about 4.5-5 Mb. Two additional markers (DXS7593 and DXS7592) were placed in the region, thereby increasing the genetic resolution. Using the deduced marker order, the analysis of key recombinants in families segregating RS allowed us to refine the critical region for RS to 0.6 Mb, between DXS418 and DXS7161.

Abnormalities, Multiple↗
PubMed1995

Determination of a maximum number of artificial inseminations by donor children per sperm donor.

OBJECTIVE: To determine a safe maximum number of artificial insemination (donor insemination [DI]) children per anonymous sperm donor. DESIGN: Multiparameter calculation model of contribution of DI to inbreeding. SETTING: Data of the collaborative DI centers and demographic population data of The Netherlands. INTERVENTIONS: Calculations of the contribution of DI to inbreeding were made, taking into account all possible unintentional consanguineous matings and consanguineous inseminations with a coefficient of inbreeding (F) of > or = 1/16 for the offspring. MAIN OUTCOME MEASURE: Coefficient of inbreeding (F). RESULTS: The contribution of DI to inbreeding was estimated to be 46.6 x 10(-6) + k (1.66 x 10(-6)) (k = number of DI children per donor). When only half-sibling matings were considered, the kmax was 32. When all possible consanguineous matings and inseminations were taken into account, kmax decreased with 28% to 25 children. CONCLUSION: Calculations of a maximum number of DI children per sperm donor, based on possible enhancement of inbreeding and given the Dutch population and DI setting, show that 25 children per DI donor is a safe threshold for clinical practice.

Consanguinity↗
PubMed1995

Rapid detection of BRCA1 mutations by the protein truncation test.

More than 75% of the reported mutations in the hereditary breast and ovarian cancer gene, BRCA1, result in truncated proteins. We have used the protein truncation test (PTT) to screen for mutations in exon 11, which encodes 61% of BRCA1. In 45 patients from breast and/or ovarian cancer families we found six novel mutations: two single nucleotide insertions, three small deletions (1-5 bp) and a nonsense mutation identified two unrelated families. Furthermore, we were able to amplify the remaining coding region by RT-PCR using lymphocyte RNA. Combined with PTT, we detected aberrantly spliced products affecting exons 5 and 6 in one of two BRCA1-linked families examined. The protein truncation test promises to become a valuable technique in detecting BRCA1 mutations.

BRCA1 Protein↗
PubMed1995

Cerebellar and brainstem hypoplasia in a child with a partial monosomy for the short arm of chromosome 5 and partial trisomy for the short arm of chromosome 10.

A child with hypoplasia of the cerebellum and brainstem in association with an unbalanced translocation, resulting in a partial deletion of the short arm of chromosome 5 and a partial trisomy of the short arm of chromosome 10, is described. A balanced translocation was present in his mother and maternal grandmother. A maternal uncle had died at the age of 4 years with the same clinical picture. After reviewing the literature, we conclude that the monosomy 5p is the most likely cause for this malformation. We suggest that the possible existence of chromosomal anomalies should always be considered in the differential diagnosis of hypoplasia of the cerebellum and/or brainstem.

Brain Stem↗
PubMed1995

Normal phenotype in two brothers with a full FMR1 mutation.

The fragile X syndrome is associated with an expanding CGG repeat in the 5' untranslated region of the first exon of the FMR1 gene. Subsequent methylation of the promoter region inhibits expression of the FMR1 gene. In two clinically normal brothers large, expanded CGG repeats and cytogenetically visible fragile sites were found. The FMR1 promoter was unmethylated and both RNA and protein could be detected. This indicates that inactivation of the FMR1 gene and not repeat expansion itself results in the fragile X phenotype. We conclude that repeat expansion does not necessarily induce methylation and that methylation is no absolute requirement for the induction of fragile sites.

Adolescent↗
PubMed1995

Refinement of the localisation of the X linked keratosis follicularis spinulosa decalvans (KFSD) gene in Xp22.13-p22.2.

X-linked keratosis follicularis spinulosa decalvans (KFSD) is a rare disorder affecting the skin and eyes. The disease was previously mapped in an extended Dutch family to Xp21.2-p22.2 between DXS16 and DXS269. Using five DNA probes and 14 CA repeat polymorphisms spanning this region an extensive linkage study was performed in the same pedigree. The highest lod scores were 12.07 for DXS365 (pRX-314) at 0 = 0, 11.72 for DXS418 (P122) at 0 = 0.015, and 10.93 for DXS989 (AFM135xe7) at 0 = 0.045. Analysis of recombination events locates the gene for KFSD between AFM291wf5 and DXS1226 (AFM316yf5). This is region Xp22.13-p22.2, an area covering approximately 1 Mb. These data confirm and greatly refine the regional localisation of KFSD and greatly improve reliability of carrier detection.

Blotting, Southern↗
PubMed1994

First-trimester prenatal diagnosis in twin pregnancies.

Two twin pregnancies at risk for a sex-linked disorder are described. Both pregnancies were dichorionic. Transabdominal sampling was chosen for prenatal diagnosis. Molecular genetic techniques raised suspicion with regard to the accuracy of the samples in one case. Second-trimester amniocentesis confirmed the error. Selective feticide of the affected fetus was performed. When first-trimester prenatal diagnosis is offered in dichorionic twin pregnancies, confirmation through molecular genetic testing can confirm that villi have been obtained from different fetuses. All parties must be aware that additional invasive diagnostic procedures in the second trimester may be required in cases of doubt.

Adult↗
PubMed1994

A practical approach to the detection of androgen receptor gene mutations and pedigree analysis in families with x-linked androgen insensitivity.

Androgen insensitivity syndrome (AIS) is an X-linked disorder in which defects in the androgen receptor gene have prevented the normal development of both internal and external male structures in 46,XY individuals. This survey reports the analysis of 11 AIS subjects. The androgen receptor gene of these subjects was analyzed using polymerase chain reaction (PCR)-single-strand conformation polymorphism analysis and sequencing or sequencing of PCR-amplified androgen receptor gene fragments alone. In total, 10 single base changes and one partial gene deletion were detected. Seven single base changes resulted in an amino acid change, one resulted in the introduction of a premature stop codon, one event represented a single base insertion resulting in a frame-shift, and one single base change affected a donor splice site. The androgen receptor protein in genital skin fibroblasts from several patients was studied with respect to molecular mass after immunoprecipitation and SDS-PAGE. Two patients expressed a truncated receptor protein in agreement with the established genomic mutation. Pedigree analysis was performed to identify possible carriers for the syndrome in families of AIS patients using single-strand conformation polymorphism and restriction site analysis of PCR products. In one case, the polymorphic (CAG)n(CAA) repeat in exon 1 encoding a polyglutamine stretch was used to identify the mutant allele in a family with X-linked partial androgen insensitivity before the identification of the actual genomic mutation. PCR-single-strand conformation polymorphism analysis proved to be a fast and reliable technique to screen for androgen receptor gene mutations and to study the androgen receptor gene of family members of AIS-affected individuals.

Base Sequence↗
PubMed1994

Hb Kurdistan [alpha 47(CE5)Asp-->Tyr], a new alpha chain variant in combination with beta (0)-thalassemia.

We have characterized the structural abnormality of a new alpha chain mutant found in a Kurdish family. The clinical and hematological investigation of eight individuals have shown that the alpha variant is associated with a beta(0)-thalassemia mutation (nonsense codon 39). The tryptic peptide map and sequencing of the abnormal peptide revealed the substitution of an aspartic acid by a tyrosine residue at position 47 of the alpha chain; furthermore, selective amplification and molecular analysis of both alpha genes have assigned the new mutation to the alpha 2 gene. The variant, named Hb Kurdistan, is clinically silent but the percentage of this hemoglobin found in the only double heterozygote for beta (0)-thalassemia and alpha-Kurdistan, presumably indicates a lower affinity of the abnormal chain for the beta polypeptides.

Adult↗
PubMed1992

Encephalocraniocutaneous lipomatosis and oculocerebrocutaneous syndrome. A differential diagnostic problem?

The authors describe a female patient with unilateral malformations of skin, cerebrum and eye. The symptoms consisted of local skin hypoplasia, skin appendages and lipomatous tissue; cysts, hypoplasia and lipomatosis of the brain; and ocular malformations. In the newborn period the symptoms led to the diagnosis of oculocerebrocutaneous (OCC) syndrome. In the first year of life the clinical course deteriorated and the psychomotor development was progressively retarded. Evaluation at the age of 15 months prompted the authors to change the diagnosis to encephalocraniocutaneous lipomatosis (ECCL). The differential diagnosis of ECCL and OCC syndromes is discussed and a possible common pathogenetic pathway of these two rare disorders is proposed.

Abnormalities, Multiple↗