Hypophosphatasia: a family study involving a case diagnosed from gingival crevicular fluid

Current concepts in hypophosphatasia: case report and literature review

BACKGROUND.  Hypophosphatasia (HP) is characterized by defective mineralization of bone and teeth because of deficient alkaline phosphatase activity. There are generally six recognized clinical forms, of which the most severe is often lethal prenatally or early in life. In milder forms, such as odontohypophosphatasia (OHP), premature exfoliation of primary teeth may be the only clinical manifestation. CASE REPORT.  A 20-month-old girl was referred to the Specialist Paediatric Salaried Dental Service within the Harrogate and District NHS Foundation Trust with mobility of tooth numbers 71 and 81. Clinical examination revealed grade III mobile 71 and 81, with minimal gingival inflammation and plaque deposits. There were no other dental findings and no significant medical history. Tooth numbers 71 and 81 exfoliated prematurely with no evidence of root resorption, shortly after presentation. Haematological and urinary investigations showed no abnormalities. Histological examination showed a complete absence of cementum. A diagnosis of OHP was made. After 10 months of dental follow-up, no further teeth have increased mobility. CONCLUSION.  Odontohypophosphatasia should be included as a differential diagnosis in children presenting with early loss of primary teeth. The dentist may be the first health care professional to whom the patient presents.

Prosthodontic rehabilitation of hypophosphatasia using dental implants: a review of the literature and two case reports

There are reports in the literature of the various dental features of hypophosphatasia, especially where it affects the deciduous dentition. The descriptions include both the manifestations of the disorder and the subsequent patterns of tooth loss. There are fewer descriptions of the effects of hypophosphatasia on the permanent dentition and little information on the subsequent prosthodontic management of these patients, particularly in relation to the use of dental implants. The aim of this paper was to review the literature on the dental effects of hypophosphatasia, present two cases and describe how one of those patients, a young adult, was successfully rehabilitated using dental implants. That latter patient's pattern of tooth loss as well as some histological and scanning electron microscopic findings of root cementum from the other case is also described.

Gingival crevicular fluid alkaline phosphatase levels in postmenopausal women: effects of phase I periodontal treatment

BACKGROUND

The aim of this study was to determine how estrogen status may possibly influence gingival crevicular fluid (GCF) alkaline phosphatase (ALP) levels in estrogen-deficient (ED) and -sufficient (ES) postmenopausal women at baseline (BL) and 1 year after periodontal phase I treatment (AT).

METHODS

Thirty-six postmenopausal women on estrogen supplements (mean serum estradiol levels >30 pg/ml; estrogen sufficient) and 37 postmenopausal women not on estrogen supplements (mean serum estradiol levels <30 pg/ml; ED) were divided into two subgroups as chronic periodontitis and clinically healthy controls after clinical and radiographic examination. The ES group consisted of 19 control (ES/C) and 17 chronic periodontitis (ES/P) patients, and the ED group consisted of 20 control (ED/C) and 17 chronic periodontitis (ED/P) patients. Plaque (PI) and gingival (GI) indices, bleeding on probing (BOP), probing depths (PD), clinical attachment loss (CAL) scores, and GCF samples were recorded at BL and AT. The levels of ALP in the GCF were measured photometrically. The paired samples Student t and Wilcoxon tests were used to compare the ALP levels and clinical parameters between BL and AT. The correlation among the ALP and clinical parameters was analyzed using the Pearson correlation.

RESULTS

The mean of all clinical parameters (PI, GI, BOP, PD, and CAL) was significantly (P <0.05) higher in periodontitis groups (ES/P and ED/P) than controls (ES/C and ED/C). Periodontitis groups (ES/P and ED/P) demonstrated significantly increased GCF volumes and GCF ALP levels (P <0.05) compared to controls (ES/C and ED/C). There were no significant differences in the concentrations of ALP between periodontitis and control groups (P >0.05). The BL GCF ALP total levels of the ED/P group were significantly higher than the ES/P group (P <0.05). The BL and AT serum ALP levels of the ED/P group were not significantly but were numerically higher than the ES/P group. One year after periodontal treatment, the GCF volume, GCF ALP total, and concentrations decreased significantly in both periodontitis groups (P <0.05). However, the GCF ALP levels were still numerically higher in the ED/P group. A positive statistical correlation was found between total ALP levels and PD (r = 0.621; P <0.05).

CONCLUSION

These data suggest that the presence of ALP in GCF is not simply a reflection of the local inflammation state and that a patient's estrogen status may possibly influence local ALP levels in GCF.

Human genes for dental anomalies

The development of the tooth at gene level is beginning to be understood. This paper reviews current knowledge and the advances in research on human genes whose defect leads to dental anomalies. Amelogenesis imperfecta (AI) is a diverse group of hereditary disorders characterized by a variety of developmental enamel defects including hypoplasia and hypomineralization, some of which have been revealed to be associated with defective amelogenin genes. The human amelogenin genes on X and Y chromosomes have been cloned and investigated extensively. Although autosomally inherited forms of AI are more common than the X-linked forms, most studies on the genes causing AI have been performed on the genes of X-linked forms. Recently, the gene for the human tuftelin protein (an enamelin) has been cloned as a candidate gene for the autosomal forms of AI with another gene on chromosome 4 involved in some families. Dentinogenesis imperfecta (DI) may be associated with osteogenesis imperfecta (OI), which is an autosomal dominant bone disease. Most patients with OI have mutations in either the COLIA1 or COLIA2 genes, which encode the alpha 1(I) or alpha 2(I) subunits of type I collagen, the major organic component of bone and dentin. Gene defects causing isolated DI have not been identified. Recently, it was demonstrated that a missense mutation of MSXI, a human homeobox gene, causes autosomal dominant agenesis of second premolars and third molars. Data indicating an important function for MSXI, the mouse counterpart of the human MSXI gene, in mouse tooth development have been accumulating since 1991. Knockout mice lacking this gene exhibited multiple craniofacial anomalies including complete tooth agenesis. X-linked anhidrotic ectodermal dysplasia (EDA), characterized by abnormal hair, teeth, and sweat glands, was demonstrated to be caused by a mutation in a novel transmembrane protein gene that is expressed in epithelial cells and in other adult and fetal tissues. The predicted EDA protein may belong to a novel class of proteins with a role in epithelial-mesenchymal signaling. Several mutations have been reported in genes causing hypophosphatasia, which is characterized by defective mineralization of the skeletal and dental structures.

Genetic analysis of hypophosphatasia

A review is presented of the recent advances in: (i) clinical features, (ii) biochemistry and molecular biology of alkaline phosphatase, (iii) genetic defect in hypophosphatasia, and (iv) prenatal diagnosis. Despite the recent progress, the pathogenesis of hypophosphatasia is far from being elucidated. More clinical cases and further characterization of the alkaline phosphatase gene mutations are needed for better understanding of the clinical spectrum of the entity.

Absence of adult dental anomalies in familial hypophosphatasia

This paper is a supplemental report on 3 previous publications about a family in which 3 male children manifested gingival recession, alveolar bone resorption and premature exfoliation of their deciduous teeth without apical root resorption and without clinical signs of inflammation. Laboratory blood and urine studies in conjunction with an analysis of periodontal microflora and family pedigrees established a diagnosis of hypophosphatasia in these 3 children, as well as their father, the paternal grandmother and paternal great-uncle. Clinical data also revealed that a son of the paternal great-uncle and his daughter were similarly affected. The family pedigree is consistent with an autosomal dominant mode of transmission. The 3 brothers are now between the ages of 18 and 22 yr and all have complete permanent dentitions. Aside from some periodontal manifestations of prior dentoalveolar trauma, most of the findings of the periodontal assessment are within normal limits. All 3 exhibit moderate to severe caries and some degree of gingival inflammation, but minimal periodontal pathosis.

Periodontal implications: medically compromised patients

The presence of systemic disease in patients requiring periodontal therapy creates challenges for management. Alteration of treatment plans, with emphasis on physician consultation and preventive periodontal care, is frequently needed to minimize the impact of periodontal disease on the systemic condition. Conversely, detection and treatment of systemic disorders may impact upon the status of the periodontium and the success of periodontal therapy. The goal of holistic patient management is facilitated by a free flow of information between the patients and their medical and dental health care providers.

Chemiluminescent assay of alkaline phosphatase in human gingival crevicular fluid: investigations with an experimental gingivitis model and studies on the source of the enzyme within crevicular fluid

The purpose of this study was to investigate how levels of gingival crevicular fluid (GCF) alkaline phosphatase (ALP) change in relation to levels of plaque and gingival inflammation in 20 adults during a 21 day period of experimental gingivitis. The source of ALP within GCF was also investigated using a repeat sampling protocol; by determining enzyme levels derived from 30 putative periodontal pathogenic and non-pathogenic species; and by examining inhibition profiles from a variety of host and bacterial ALP isoenzymes. Total 30-s GCF ALP levels increased significantly (p < 0.002) during experimental gingivitis and preceded an increase in gingival index (GI) by approximately 7 days. Enzyme levels correlated with GCF volume (R = 0.7; p < 0.0001), but repeat sampling indicated that entry of ALP into the gingival crevice was independent of the rate of fluid flow. Only 5 of the bacterial species investigated produced clearly detectable levels of ALP in culture supernatants, these were P. gingivalis (381), P. intermedia (581), P. nigrescens (8944), Dentin P. gingivalis (TW 471: clinical isolate) and C. ochracea (25). Levamisole inhibition and studies on suspensions of washed plaque demonstrated that host-derived ALP contributed to > 80% of the enzyme in GCF. We conclude that elevated 30-s GCF ALP levels measured using the chemiluminescent assay reported, are detectable before increases in gingival indices and appear to be a better marker of gingival inflammation than ALP concentrations. The major source of ALP within GCF is host derived and in early inflammatory disease is likely to be of polymophonuclear leukocyte origin.

Site-specific alkaline phosphatase levels in gingival crevicular fluid in health and gingivitis: cross-sectional studies

Using a recently developed chemiluminescent assay enabling alkaline phosphatase (ALP) quantification in nanolitre volumes of gingival crevicular fluid (GCF), we have investigated GCF ALP levels in health and in the presence of gingivitis. In gingival health, there was a site-specific pattern of ALP concentration with higher enzyme concentrations around the upper and lower anterior teeth. Furthermore, clinically normal sites that had been subjected to different levels of plaque control produced significantly different ALP levels, (p < 0.03). This indicates that biochemical components of GCF may be used to measure subclinical inflammatory status. The ratio of GCF to serum ALP varied from 6:1 to 11:1, suggesting that a major source of the enzyme is through local production. The main cross-sectional study of 30 patients with gingivitis (276 sites) demonstrated that total GCF ALP levels, collected over a 30-s sampling time were higher for a gingival index of 1 than of 0 (p < 0.014). There was no significant relationship between total GCF ALP and plaque levels of the enzyme, and analysis of plaque within the study group demonstrated very low levels of ALP, indicating that the enzyme is likely to be largely derived from the periodontal tissues. The ratio of GCF ALP levels to those of saliva within individuals was 530:1, thereby eliminating saliva contamination as a risk, when total GCF ALP is being measured.

Interpretation and clinical significance of alkaline phosphatase isoenzyme patterns

Alkaline phosphatase (ALP, EC 3.1.3.1) is a membrane-bound metalloenzyme that consists of a group of true isoenzymes, all glycoproteins, encoded for by at least four different gene loci: tissue-nonspecific, intestinal, placental, and germ-cell ALP. Through posttranslational modifications of the tissue-nonspecific gene, for example, through differences in carbohydrate composition, bone and liver ALP are formed. Nowadays, most commercially available methods for separating or measuring ALP isoenzymes are easy to perform and sensitive and allow for reproducible and quantitative results. As more isoenzymes and isoforms have been characterized, confusion has arisen due to the many different names they were given. For the sake of simplicity and because of structural analogies, we propose an alternative nomenclature for the ALP isoenzymes and isoforms based on their structural characteristics: soluble, dimeric (Sol), anchor-bearing (Anch), and membrane-bound (Mem) liver, bone, intestinal, and placental ALP. Together with lipoprotein-bound liver ALP and immunoglobulin-bound ALP, these names largely fit the many forms of ALP one can encounter in human serum and tissues. The clinically relevant isoenzymes are sol-liver, Mem-liver, lipoprotein-bound liver, and Sol-intestinal ALP in liver diseases, and Sol-bone and Anch-bone ALP in bone diseases. Many different isoenzyme patterns can be found in malignancies and renal diseases. This test provides the clinician with valuable information for diagnostic purposes as well as for follow-up of patients and monitoring of treatment. However, ALP isoenzyme determination will only provide clinically useful information if the patterns are correctly interpreted. In this respect, care should be taken to use the proper reference ranges, taking into account the age and sex of the patient. A normal total ALP activity does not rule out the presence of an abnormal isoenzyme pattern, particularly in children. Separating ALP into its isoenzymes adds considerable value to the mere assay of total ALP activity.

Hypophosphatasia: dental aspects and mode of inheritance

Hypophosphatasia is rare enzymopathy that normally presents within the first few years of life and often has profound effects upon the periodontium. It is a heritable disorder characterised by defective mineralisation of the skeletal and dental structures of the body and a deficiency in the liver/bone/kidney (L/B/K) isoenzyme of alkaline phosphatase (ALP). There has been a tremendous advance in our knowledge of this condition over the last decade due to the advent of highly specific DNA probes and novel microanalytical techniques. This paper aims to review current literature about hypophosphatasia with special reference to the dental aspects of the condition and to shed light upon the controversial area of its mode of genetic inheritance. It is concluded that hypophosphatasia may result from the existence of 2 defective alleles, which alone or in combination may cause the condition. One allele is expressed in an autosomal dominant manner producing milder phenotypic characteristics, whilst the other is expressed in an autosomal recessive manner producing the more severe clinical form that often results in neonatal death. The milder phenotypes may go undiagnosed and the consequence of this in genetic counselling terms is extremely important.

A new ultrasensitive chemiluminescent assay for the site-specific quantification of alkaline phosphatase in gingival crevicular fluid

The search for markers of periodontal disease activity and progression has accelerated over the last decade, in an effort to replace existing subjective clinical measures of periodontal health status. Research is being aimed at establishing more objective and quantitative methodology, capable of rapid diagnosis prior to the appearance of clinical signs of destructive disease. Such tests need to be sensitive enough to evaluate individual periodontal sites in health as well as disease states. We report the development of a new chemiluminescent assay for the enzyme alkaline phosphatase, that is capable of quantifying the enzyme in sub-microliter volumes of gingival crevicular fluid and serum. The technique will measure alkaline phosphatase (ALP) whilst immobilised on paper strips, without the need for an elution stage. It is simple, versatile and amenable to chair-side use. We discuss in detail the assay procedure and have examined levels of ALP in 11 adult volunteers with clinically healthy periodontal tissues. The mean ALP concentration was 2135 IU/L for GCF and 183 IU/L for serum, a 12-fold difference. There also appeared to be an "oral pattern" of enzyme distribution in healthy periodontal sites, with levels being higher in the anterior region of the mouth and highest in the lower anterior region.