[Is there more to hypodontia then missing teeth?] / Ernstige hypodontie: meer dan alleen ontbrekende gebitselementen?

Dental care professionals regularly see patients with hypodontia. Hypodontia can be acquired, for example through chemotherapy or radiation at a young age, but is hereditary in most patients. Due to an error (pathogenic variant) in one of the many genes that control odontogenesis, the formation of the tooth germ is disrupted at an early stage. The genes involved are not only crucial for tooth development, but they also play an important role in other physical processes. This article provides background information on hypodontia. Based on an inventory of gastrointestinal complaints in patients with hypodontia and a case description of the simultaneous occurrence of a coagulation disorder and hypodontia, the importance of a broad view of this patient group is illustrated. It is concluded that, in addition to a dental assessment, examination of these patients should include a limited physical examination and the medical history of the patient and his close relatives.

The significance of fragile X mental retardation gene 1 CGG repeat sizes in the normal and intermediate range in women with primary ovarian insufficiency.

STUDY QUESTION: Are fragile X mental retardation gene 1 (FMR1) CGG repeats in the normal and intermediate range (up to 55 repeats) associated with primary ovarian insufficiency (POI) in a large case-control study? SUMMARY ANSWER: No association was found between CGG repeats of intermediate size and POI compared with controls. WHAT IS KNOWN ALREADY: CGG repeats in the FMR1 gene in the premutation range (55-200 repeats) have consistenly associated with POI. Intermediate range CGG repeats have been considered for a potential association with POI. STUDY DESIGN, SIZE: A case-control study in 375 well-phenotyped Dutch women diagnosed with POI and 3368 controls with natural menopause ≥40 years of age. PARTICIPANTS/MATERIALS, SETTING, METHODS: The FMR1 CGG repeat number was determined by PCR amplification in women diagnosed with POI and women with a known age at natural menopause ≥40 years. The prevalence of intermediate sized CGG repeats (45-54 repeats) was compared between POI cases and controls using Fisher's exact test. Differences in mean CGG repeat lengths on allele 1 and allele 2 between POI cases and controls were tested using analysis of variance. MAIN RESULTS AND THE ROLE OF CHANCE: The frequency of intermediate sized CGG repeats on the allele with the longest triple repeat number was not statistically significantly different between POI cases and controls (2.7 and 3.8%, respectively, odds ratio 0.72, 95% confidence interval: 0.38-1.39, P = 0.38). In women with POI, linear regression analysis for age at POI diagnosis and CGG repeat size also failed to show any association (ß = -0.018, P = 0.74). LIMITATIONS, REASONS FOR CAUTION: FMR1 CGG repeat lengths in POI cases and controls were genotyped in two different laboratories. The distributions of CGG repeats may vary among the different ethnic populations in our study. Also, in our study women with primary amenorrhea (N = 17) were included in the POI group. WIDER IMPLICATIONS OF THE FINDINGS: We found no association between intermediate sized CGG repeats and POI compared with controls. Therefore, a role for FMR1 CGG repeat sizes up to 55 repeats in the ovarian ageing process may be questioned. Moreover, there seems limited value in the evaluation of normal- and intermediate FMR1 repeat size in the diagnostic work-up of women affected by POI, or for prognostic purposes in women at risk of developing POI. STUDY FUNDING/COMPETING INTERESTS: The Prospect-EPIC study was funded by 'Europe Against Cancer' Program of the European Commission (SANCO); the Dutch Ministry of Health; the Dutch Cancer Society; ZonMW the Netherlands Organization for Health Research and Development; World Cancer Research Fund (WCRF) and the Dutch Heart Association.

The association of CGG repeats in the FMR1 gene and timing of natural menopause.

STUDY QUESTION: Is there an association between the number of CGG repeats in the FMR1 gene in the normal and intermediate range and age at natural menopause? SUMMARY ANSWER: The number of CGG repeats in the normal and intermediate range in the FMR1 gene was not associated with age at natural menopause. WHAT IS KNOWN ALREADY: Excessive triple CGG repeats in the FMR1 gene have been widely associated with primary ovarian insufficiency. Recently, the number of CGG repeats in the normal and intermediate range (up to 55 repeats) was found to be associated with serum levels of anti-Müllerian hormone and follicle-stimulating hormone, as markers for ovarian ageing. This suggests that repeats in the normal and intermediate range could be involved in the rate of exhaustion of the ovarian primordial follicle pool and ultimately the timing of menopause. STUDY DESIGN, SIZE: Cross-sectional study in a population-based sample of 3611 Caucasian women with natural menopause. PARTICIPANTS/MATERIALS, SETTING, METHODS: The FMR1 CGG repeat number was determined by PCR amplification in 3611 women with a known age at natural menopause. A possible relation between CGG repeats in the normal and intermediate range (up to 55 repeats) and menopausal age were analysed in various ways, including linear regression analysis and analysis of variance. MAIN RESULTS AND THE ROLE OF CHANCE: The number of CGG repeats in the normal and intermediate range in the FMR1 gene was not associated with age at natural menopause. The mean age at menopause was 50.30 (± 4.2) years for women with <45 repeats and 50.64 (± 3.4) years for women with intermediate-sized repeats (P = 0.37). Linear regression analysis of the number of CGG repeats showed no association with menopausal age (ß = 0.019, P = 0.16). LIMITATIONS, REASONS FOR CAUTION: In our cohort, age at menopause was self-reported and determined retrospectively. WIDER IMPLICATIONS OF THE FINDINGS: Earlier observations suggesting that the number of CGG repeats in the normal and intermediate range is associated with the individual variation of the ovarian ageing process could not be confirmed in the current, large sample size study. A relation between the number of CGG repeats in the normal and intermediate range and age at natural menopause appeared to be absent. This finding questions the role of CGG repeat sizes in the ovarian ageing process.

Three novel mutations in five unrelated subjects with hereditary protein S deficiency type I.

A panel of eight unrelated subjects with inherited type I protein S deficiency was screened for mutations in the PROS1 gene. In five subjects an abnormality was found but mutations were not detected in the remaining three subjects. Two subjects shared a G-->A transition at position +5 of the donor splice site consensus sequence of intron 10. Also in two subjects an A-->T transversion was detected in the stopcodon of the PROS1 gene; this transversion predicts a protein S molecule that is extended by 14 amino acids. The fifth subject was found to possess two sequence abnormalities. One allele carried a G-->A transition near the donor splice junction of intron 2, but this abnormality is probably neutral, since it was inherited from the parent with normal protein S antigen levels. In the other allele a single T insertion in codon -25 was found. Analysis of platelet RNA showed that only the mRNA with the A-->T mutation in the stopcodon is present in amounts comparable to wildtype RNA. mRNA from the alleles with the other two mutations was either undetectable or present in greatly reduced amounts. The latter indicates that a mRNA based approach is not feasible for the genetic analysis of protein S deficiency type I.

Somatic mutations of the RET proto-oncogene are not required for tumor development in multiple endocrine neoplasia type 2 (MEN 2) gene carriers.

Germ line mutations in one allele of the RET proto-oncogene predispose to the multiple endocrine neoplasia type 2 (MEN 2) syndromes. To investigate whether these inherited mutations alone can cause the development of tumors in vivo (oncogene model) or whether somatic mutations in the homologous RET allele are required for tumorigenesis (tumor suppressor gene model), we analyzed the entire coding region of both alleles of the RET gene in two MEN 2A and two MEN 2B tumors by reverse transcription-PCR and direct sequencing. No tumor-specific mutations could be detected in either allele of the RET gene in these tumors. Unlike the molecular mechanism in other hereditary tumor syndromes, somatic mutations in the homologous allele are apparently not required in MEN 2 tumorigenesis. Thus, RET genes with MEN 2-specific germ line mutations act as dominantly transforming oncogenes in vivo.

Human protein S cDNA encodes Phe-16 and Tyr 222 in consensus sequences for the post-translational processing.

Partial cDNAs coding for human protein S were isolated from a pUC9 human liver cDNA library. Together, the overlapping clones span a (partial) 5'-non-coding region, and the complete protein S coding and 3'-untranslated regions. The derived amino acid sequence deviates at five positions from two previously reported protein S sequences. Two of these differences (Phe instead of Leu at position -16 and Tyr instead of Asp at position 222) are found in regions that are important for the post-translational modification of protein S, the gamma-carboxylation of glutamic acid and the hydroxylation of asparagine, respectively.

A diagnostic protocol for adult-onset glycogen storage disease type II.

To analyze the diagnostic value of various laboratory tests for the confirmation of adult-onset glycogen storage disease type II (GSD II), we performed a clinical, biochemical, and genetic study of 18 patients with this disease. Measurement of acid alpha-glucosidase (GAA) activity in muscle and histopathologic analysis of muscle tissue appeared to have no additional value when GAA activity in leukocytes was clearly deficient. Our study showed that creatine kinase elevation is a sensitive marker of GSD II. A diagnostic protocol is formulated.

Mutations in severe, type III von Willebrand's disease in the Dutch population: candidate missense and nonsense mutations associated with reduced levels of von Willebrand factor messenger RNA.

The von Willebrand factor (vWF) genes of nine unrelated, severe, type III von Willebrand's disease (vWD) patients (six of Dutch origin) and four unrelated Dutch type I vWD patients were screened for mutations in exons that contain CGA codons (Arg), which are liable to mutation to TGA stop codons. The nine exons of the vWF gene (3, 8, 9, 10, 28, 31, 32, 43 and 45) that contain all the CGA codons (11 in total) of the vWF cDNA were amplified by the polymerase chain reaction and screened for mutations by single-strand conformation polymorphism analysis, restriction enzyme - and/or nucleotide sequence analysis. Three of the severe vWD patients were found to be heterozygous for a nonsense mutation: CGA Arg 2535-->TGA Stop. Three other severe vWD patients were homozygous for a single nucleotide substitution, AAC Asn 2546-->TAC Tyr. The transcription of these mutated alleles was tested by cDNA dependent amplification of platelet RNA. The level of transcription product was strongly reduced for either mutant allele.

Studies of the interaction between human protein S and human C4b-binding protein using deletion variants of recombinant human protein S.

Human protein S interacts noncovalently with human C4b-binding protein (C4BP). We have studied this interaction using deletion variants of recombinant human protein S. Two deletion variants were constructed by restriction enzyme digestion and in vitro site-specific mutagenesis of the human protein S cDNA. The variants were stably expressed in C127 cells. Recombinant proteins were purified using Fast Flow Q anion-exchange chromatography. The activated protein C (APC) cofactor activity, C4BP binding properties and reactivity to different monoclonal antibodies against human protein S were examined. The first variant (E variant), which has a deletion of the third epidermal growth factor (EGF)-like domain (deletion of exon VII, corresponding to amino acid residues ASP-160 to Asp-202) expresses normal APC cofactor activity in a plasma system. This activity was inhibited by the addition of purified C4BP. The second variant (L variant), which has a deletion of the C-terminal loop of the sex hormone binding globulin (SHBG)-like domain (deletion of exon XV, corresponding to amino acid residues Asp-583 to Ser-635) also expresses normal APC cofactor activity in plasma. This activity could only be partially inhibited by the addition of purified C4BP. Binding of the recombinant proteins to C4BP was studied in a system using purified proteins. The E variant binds to C4BP with the same affinity similar as recombinant wild type protein S (apparent Kd approximately 10(-10) M). The L variant, however, shows a markedly reduced affinity for binding to C4BP (apparent Kd approximately 10(-7) M).(ABSTRACT TRUNCATED AT 250 WORDS)

A mutation in the protein S pseudogene is linked to protein S deficiency in a thrombophilic family.

Probands from 15 unrelated families with hereditary protein S deficiency type I, that is having a plasma total protein S concentration fifty percent of normal, were screened for abnormalities in their protein S genes by Southern analysis. Two probands were found to have a deviating DNA pattern with the restriction enzyme MspI. In the two patients the alteration concerned the disappearance of a MspI restriction site, CCGG, giving rise to an additional hybridizing MspI fragment. Analysis of relatives of both probands showed that in one family the mutation does not co-segregate with the phenotype of reduced plasma protein S. In the family of the other proband, however, complete linkage between the mutated gene pattern and the reduced total protein S concentration was found: 12 heterozygous relatives showed the additional MspI fragment but none of the investigated 26 normal members of the family. The mutation is shown to reside in the PS beta gene, the inactive protein S gene. The cause of type I protein S deficiency, a defect PS alpha gene has escaped detection by Southern analysis. No recombination has occurred between the PS alpha gene and the PS beta gene in 23 informative meioses. This suggests that the two protein S genes, located near the centromere of chromosome 3, are within 4 centiMorgan of each other.

Expression and characterization of recombinant human protein S in heterologous cells--studies of the interaction of amino acid residues leu-608 to glu-612 with human C4b-binding protein.

Mouse C127 epithelioid cells were genetically engineered to produce biologically active gamma-carboxylated human protein S. A full length human protein S cDNA was cloned into a bovine papilloma virus (BPV) based shuttle vector under the transcriptional control of the Moloney murine sarcoma virus enhancer and the mouse metallothionein promoter. Stable expression was obtained in transfected C127 cells. Expression of gamma-carboxylated protein S was dependent on the presence of vitamin K in the culture medium. Protein sequence analysis showed that recombinant and plasma protein S have the same amino terminal sequence. Analysis of specific post-translationally modified amino acids shows that recombinant protein S is fully gamma-carboxylated and fully beta-hydroxylated. Immunoblotting analysis using polyclonal and monoclonal antibodies shows that recombinant protein S has a slightly higher molecular weight than plasma protein S. After N-Glycanase treatment, identical molecular weights are observed for recombinant and plasma protein S, indicating that the difference is caused by differences in the N-linked carbohydrate side chains. Recombinant protein S also demonstrates normal cofactor activity for activated protein C in a clotting assay. Binding studies with the complement component, C4b-binding protein (C4BP), shows that recombinant protein S binds to C4BP with the same apparent affinity as plasma protein S. Two variant molecules are also tested for their binding to C4BP. The first variant has a replacement of amino acid residue leu-608 by val and was designated B variant. The second variant has three alterations, at positions 609, 611 and 612 where the acidic amino acid residues asp, asp and glu were replaced by asn, asn and gln, respectively and this variant was designated C variant.(ABSTRACT TRUNCATED AT 250 WORDS)

The human protein S locus: identification of the PS alpha gene as a site of liver protein S messenger RNA synthesis.

The protein S locus, situated on chromosome 3, consists of two protein S genes. Here, we report the cloning and complete nucleotide sequence of the 3'-untranslated region of the two genes designated PS alpha and PS beta. Both regions span approximately 1,200 nucleotides. They show a high degree (-97%) of homology, with deviations caused by small deletions, insertions and point mutations. Comparison of PS alpha and PS beta with the reported protein S liver cDNAs, shows that the latter all originate from the PS alpha gene. The PS alpha gene therefore is marked as the major site of synthesis of liver protein S mRNA. Sequence comparison with the bovine protein S cDNA reveals that the PS beta gene has accumulated a few more mutations than the PS alpha gene since duplication of the ancestral protein S gene that seems to have occurred recently during primate evolution.

Intron-exon organization of the active human protein S gene PS alpha and its pseudogene PS beta: duplication and silencing during primate evolution.

The human protein S locus on chromosome 3 consists of two protein S genes, PS alpha and PS beta. Here we report the cloning and characterization of both genes. Fifteen exons of the PS alpha gene were identified that together code for protein S mRNA as derived from the reported protein S cDNAs. Analysis by primer extension of liver protein S mRNA, however, reveals the presence of two mRNA forms that differ in the length of their 5'-noncoding region. Both transcripts contain a 5'-noncoding region longer than found in the protein S cDNAs. The two products may arise from alternative splicing of an additional intron in this region or from the usage of two start sites for transcription. The intron-exon organization of the PS alpha gene fully supports the hypothesis that the protein S gene is the product of an evolutional assembling process in which gene modules coding for structural/functional protein units also found in other coagulation proteins have been put upstream of the ancestral gene of a steroid hormone binding protein. The PS beta gene is identified as a pseudogene. It contains a large variety of detrimental aberrations, viz., the absence of exon I, a splice site mutation, three stop codons, and a frame shift mutation. Overall, the two genes PS alpha and PS beta show between their exonic sequences 96.5% homology. Southern analysis of primate DNA showed that the duplication of the ancestral protein S gene has occurred after the branching of the orangutan from the African apes.(ABSTRACT TRUNCATED AT 250 WORDS)

Partial protein S gene deletion in a family with hereditary thrombophilia.

Familial thrombophilia, the hereditary predisposition to venous thromboembolic disease, is associated with a protein S deficiency in approximately 8% of the cases. Laboratory measurements of total protein S antigen in affected families have indicated that heterozygotes, ie, individuals carrying both a normal and a defective protein S gene, are severely at risk of developing venous thrombosis at a young age. The recent isolation of protein S cDNA has enabled us to start a search for genetic defects in the protein S gene of heterozygotes. Using Southern blotting on probands of six unrelated families with hereditary protein S deficiency, one proband was found to have a grossly abnormal gene pattern. The abnormality appears to involve at least the deletion of the middle portion of the protein S coding sequence. Family analysis showed that the defect cosegregates with the protein S deficiency. These data agree with the notion that hereditary thrombophilia associated with protein S deficiency is indeed directly the result of a defect in the protein S gene.

Mutation analysis for prenatal diagnosis of hereditary tyrosinaemia type 1.

Hereditary tyrosinaemia type 1 is a rare but serious metabolic disorder with an autosomal recessive mode of inheritance. We describe the prenatal diagnosis of an affected fetus performed by DNA-mutation analysis and a subsequent pregnancy with a healthy child in the same family.

Criteria for mutation analysis in MEN 1-suspected patients: MEN 1 case-finding.

BACKGROUND: Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal, dominantly inherited cancer syndrome, with tumours in various endocrine glands. In 1997 the responsible tumour suppressor gene was identified. MEN1 gene germ-line mutations are detected in the vast majority of MEN 1 patients, however, with regard to case-finding, unfortunately only at a very low frequency in patients with apparently sporadic MEN 1-related tumours. In order to increase the detection rate of disease gene carriers among patients with apparently sporadic MEN 1-related tumours, clinical criteria were needed. DESIGN AND RESULTS: In this study MEN1 gene germ-line mutations were revealed in 16/16 MEN 1 patients/families (100%). Based on our clinical experience with MEN 1 patients/families we formulated clinical criteria to identify disease gene carriers among patients with apparently sporadic MEN 1-related tumours. The criteria for MEN 1-suspected patients are: young age at onset (< 35 years) and/or multiple MEN 1-related lesions in a single organ or two distinct organs affected. Application of these criteria yielded MEN1 gene germ-line mutations in nine of 15 MEN 1-suspected patients (60%), thus identifying novel MEN 1 families. Follow up was also guaranteed for patients not fulfilling these criteria. CONCLUSIONS: The clinical criteria for MEN 1-suspected patients increase the detection rate of germ-line MEN1 gene mutations among patients with apparently sporadic MEN 1-related tumours. These criteria may be used for (presymptomatic) identification of MEN 1 disease gene-carriers, thus enabling early detection of tumour development and timely treatment, as well as genetic counselling.

Mutation analysis of the RET proto-oncogene in Dutch families with MEN 2A, MEN 2B and FMTC: two novel mutations and one de novo mutation for MEN 2A.

Hereditary C-cell carcinoma is encountered in multiple endocrine neoplasia type 2A (MEN 2A), MEN 2B, and familial medullary thyroid carcinoma (FMTC). Mutations of the RET proto-oncogene are associated with all three diseases. To obtain an insight into the molecular heterogeneity of MEN 2 syndromes and FMTC in the Netherlands, probands of 20 MEN 2A families, two FMTC families, and seven MEN 2B families were analyzed by the polymerase chain reaction (PCR), DNA sequencing, and restriction enzyme digestion for abnormalities in the RET proto-oncogene. RET mutations were found in all cases. All MEN 2A families had a mutation involving one of five cysteine codons in exons 10 and 11 of RET. Two novel dinucleotide mutations and a de novo mutation were found. Both FMTC families had a mutation of the Cys at codon 618. All MEN 2B probands carried a Met to Thr mutation in exon 16. All mutations could be confirmed by restriction enzyme digestion of PCR amplicons. Identification of the RET mutation in the Dutch population with hereditary C-cell carcinoma facilitates genetic testing for families or individuals at risk for MEN 2A, FMTC, and MEN 2B.

A patient with von Willebrand's disease characterized by a compound heterozygosity for a substitution of Arg854 by Gln in the putative factor-VIII-binding domain of von Willebrand factor (vWF) on one allele and very low levels of mRNA from the second vWF allele.

We describe a patient with a lifelong bleeding disorder previously classified as von Willebrand's disease (vWD) type I. The factor VIII (FVIII) level in this patient was disproportionately low and we showed that this was due to a decreased factor VIII binding capacity of her vWF. To characterize the molecular defect in this type of vWD, a cDNA-dependent polymerase chain reaction (PCR) amplification was performed using platelet RNA as a template. Direct sequencing of the amplified fragment, which encodes for the FVIII-binding domain, showed a single nucleotide change in exon 20 at codon 854, resulting in the substitution of CAG glutamine (Gln) for CGG arginine (Arg). At the level of the cDNA only the mutated sequence was found, whereas at genomic DNA level the patient was heterozygous for this mutation. This patient is therefore a compound heterozygote for a point mutation resulting in a FVIII-binding defect and a vWF allele with low transcript levels.