Reduction in head size in patients with aspartylglucosaminuria

OBJECTIVE

To show that the head may shrink in adult patients with aspartylglucosaminuria (AGU), a neurodegenerative disease.

METHOD

The head circumference (HC) of 40 adult patients (age at baseline 15 to 47) was measured twice with an interval of 10 years. Of these 40, 21 aged 15-47 and 19 young patients aged 5-14 as well as 40 healthy controls underwent lateral cephalometric radiography.

RESULTS

During 10 years' follow-up, the HC of 26 (65%) had decreased by 1 to 4.5 cm (mean 1.7, P < 0.001). Evaluation of lateral skull radiographs revealed that patients aged 15 or more had significantly thicker skulls than did younger patients (P = 0.015). Mean intracranial length (glabella-opisthocranium) of the patients aged 15 or more was significantly shorter than in patients aged 14 years or less (P = 0.029). These measurements indicated that brain volume had decreased.

CONCLUSIONS

Macrocephalia in childhood followed by reduced brain volume in adulthood is evident in patients with AGU and is reflected by a decrease in head size.

MSX1 gene is deleted in Wolf-Hirschhorn syndrome patients with oligodontia

Abnormalities of the short arm of chromosome 4 cause multiple congenital malformations, including craniofacial, oral, and dental manifestations. A candidate gene for oral defects in this region is MSX1, which is mandatory for normal oral and tooth development. We examined the dentition and the presence of MSX1 in eight Finnish patients with abnormalities of 4p, including seven cases of Wolf-Hirschhorn syndrome. Five of the Wolf-Hirschhorn syndrome patients presented with agenesis of several teeth, suggesting that oligodontia may be a common (even though previously not well-documented) feature in Wolf-Hirschhorn syndrome. In fluorescence in situ hybridization (FISH) analysis, the five patients with oligodontia lacked one copy of MSX1, while the other three had two hybridization signals. One of these presented with the only case of cleft palate among the patients. Our result confirms that haploinsufficiency for MSX1 serves as a mechanism that causes selective tooth agenesis but, alone, is not enough to cause oral clefts.

Craniofacial features in Cohen syndrome: an anthropometric and cephalometric analysis of 14 patients

Cohen syndrome (Mendelian Inheritance in Man [MIM] no. 216550) is a rare, autosomal-recessive inherited disorder with mental retardation and a typical appearance. The condition is relatively common in Finland where 35 patients have been diagnosed. We studied 22 patients in detail, obtaining anthropometric measurements of the head and face, and cephalometric radiographs of 14 patients (14-57 years of age). Measurements of patients were compared to population norms and matched controls. Anthropometric analysis confirmed and quantified the previously described syndrome features: small head size [-4 standard deviations (SD)], with varying cephalic index. Width of the upper face was close to normal, but width of the lower face was small. Philtrum length was shorter than in healthy controls (p = 0.0039 in females and p = 0.0014 in males). The measurements from standardized radiographs revealed short cranial base dimensions (-2.2 and -2.6 SD), but normal cranial base angles. Prognathism of jaws was within normal limits. Reduced head size (microcephaly), short philtrum and small cranial base dimensions are essential features in Cohen syndrome. In addition, most patients had forward-inclined upper incisors and maxillary prognathia. We conclude that exact measurements mostly confirmed the Cohen syndrome description based previously on clinical impression.

Identification of a nonsense mutation in the PAX9 gene in molar oligodontia

Development of dentition is controlled by numerous genes, as has been shown by experimental animal studies and mutations that have been identified by genetic studies in man. Here we report a nonsense mutation in the PAX9 gene that is associated with molar tooth agenesis in a Finnish family. The A340T transversion creates a stop codon at lysine 114, and truncates the coded PAX9 protein at the end of the DNA-binding paired-box. All the affected members of the family were heterozygous for the mutation. The tooth agenesis phenotype involves all permanent second and third molars and most of the first molars and resembles the earlier reported phenotype that was also associated with a PAX9 mutation. The phenotype is presumably a consequence of haploinsufficiency of PAX9. In another Finnish family with molar tooth agenesis, we could not find similar sequence changes in PAX9.

Characteristics of incisor-premolar hypodontia in families

Nonsyndromic tooth agenesis is a genetically and phenotypically heterogenous condition. It is generally assumed that different phenotypic forms are caused by different mutated genes. We analyzed inheritance and phenotype of hypodontia and dental anomalies in 214 family members in three generations of 11 probands collected for genetic linkage study on incisor-premolar hypodontia (IPH). Our analysis confirms the autosomal-dominant transmission with reduced penetrance of IPH. The prevalence of hypodontia and/or peg-shaped teeth was over 40% in first- and second-degree relatives and 18% in first cousins of the probands. Four of nine noted obligate carriers of hypodontia gene had dental anomalies, including small upper lateral incisors, ectopic canines, taurodontism, and rotated premolars. These anomalies were also observed at higher than normal frequency in relatives affected with hypodontia. We conclude that incisor-premolar hypodontia is a genetic condition with autosomal-dominant transmission and that it is associated with several other dental abnormalities.

A syndrome with midface asymmetry, defective modelling of the skeleton, catch-up growth and truncal obesity

We report follow-up from birth up to 16 years of age of a patient with a previously undescribed combination of dysmorphic features. These include: intrauterine growth retardation developing to normal adult stature with truncal obesity, asymmetry of the midface skeleton with severe orthodontic problems, brachydactyly of the hands and feet, wide medial phalanges of the fingers, partial soft tissue syndactyly, simian creases and normal mental development. We consider other differential diagnoses and suggest that the patient represents a hitherto undescribed syndrome.

Comparison of virulence factors of oral Candida dubliniensis and Candida albicans isolates in healthy people and patients with chronic candidosis

We determined differences in the expression of certain virulence factors between oral Candida dubliniensis and Candida albicans species. In addition, clonal differences were sought among C. albicans isolates recovered from patients with and without compromised immune system. The material comprised 93 clinical yeast isolates originated in 40 subjects (1-5 isolates per subject). All 26 C. dubliniensis isolates and 46 C. albicans isolates originated from healthy routine dental clinic patients. Additionally, 21 C. albicans isolates were collected from patients with autoimmune polyendocrinopathy-candidosis-ectodermal dystrophy (APECED), who have chronic candidosis as one manifestation of their immunocompromising disease. Polymerase chain reaction amplification using the random sequence primer OPE-03 enabled grouping of the C. dubliniensis isolates in 2 genotypes (I and II) and C. albicans isolates in 15 genotypes (I-XV). No significant difference was found in the distribution of genotypes between the patients with APECED and the healthy subjects. C. dubliniensis isolates exhibited high-frequency phenotypic switching significantly more frequently than did C. albicans isolates, and vice versa regarding phospholipase and proteinase production. Proteinase production was significantly more frequent among C. albicans genotype V than genotype IX isolates. No significant difference was found in expression of virulence factors of C. albicans isolates between the patients with APECED and the healthy subjects.

CBFA1 mutation analysis and functional correlation with phenotypic variability in cleidocranial dysplasia

Cleidocranial dysplasia (CCD) is a dominantly inherited skeletal dysplasia caused by mutations in the osteoblast-specific transcription factor CBFA1. To correlate CBFA1 mutations in different functional domains with the CCD clinical spectrum, we studied 26 independent cases of CCD and a total of 16 new mutations were identified in 17 families. The majority of mutations were de novo missense mutations that affected conserved residues in the runt domain and completely abolished both DNA binding and transactivation of a reporter gene. These, and mutations which result in premature termination in the runt domain, produced a classic CCD phenotype by abolishing transactivation of the mutant protein with consequent haploinsufficiency. We further identified three putative hypomorphic mutations (R391X, T200A and 90insC) which result in a clinical spectrum including classic and mild CCD, as well as an isolated dental phenotype characterized by delayed eruption of permanent teeth. Functional studies show that two of the three mutations were hypomorphic in nature and two were associated with significant intrafamilial variable expressivity, including isolated dental anomalies without the skeletal features of CCD. Together these data show that variable loss of function due to alterations in the runt and PST domains of CBFA1 may give rise to clinical variability, including classic CCD, mild CCD and isolated primary dental anomalies.

Excessive infantile growth and early pubertal growth spurt: typical features in patients with aspartylglycosaminuria

Rapid infantile growth was the first clinical sign in patients (n = 51) with aspartylglycosaminuria, a lysosomal storage disorder. Even if young children with aspartylglycosaminuria were tall for their age, an early but weak pubertal growth spurt in both sexes resulted in reduced adult heights.

Overgrowth of oral mucosa and facial skin, a novel feature of aspartylglucosaminuria

Aspartylglucosaminuria (AGU) is a lysosomal storage disorder caused by deficiency of aspartylglucosaminidase (AGA). The main symptom is progressive mental retardation. A spectrum of different mutations has been reported in this disease, one missense mutation (Cys163Ser) being responsible for the majority of Finnish cases. We were able to examine 66 Finnish AGU patients for changes in the oral mucosa and 44 of these for changes in facial skin. Biopsy specimens of 16 oral lesions, 12 of them associated with the teeth, plus two facial lesions were studied histologically. Immunohistochemical staining for AGA was performed on 15 oral specimens. Skin was seborrhoeic in adolescent and adult patients, with erythema of the facial skin already common in childhood. Of 44 patients, nine (20%) had facial angiofibromas, tumours primarily occurring in association with tuberous sclerosis. Oedemic buccal mucosa (leucoedema) and gingival overgrowths were more frequent in AGU patients than in controls (p<0.001). Of 16 oral mucosal lesions studied histologically, 15 represented fibroepithelial or epithelial hyperplasias and were reactive in nature. Cytoplasmic vacuolisation was evident in four. Immunohistochemically, expression of AGA in AGU patients' mucosal lesions did not differ from that seen in corresponding lesions of normal subjects. Thus, the high frequency of mucosal overgrowth in AGU patients does not appear to be directly associated with lysosomal storage or with alterations in the level of AGA expression.

Dental maturity is advanced in Fragile X syndrome

Fragile X (FraX) syndrome is the most common cause of inherited mental retardation. The FraX gene (FMR1) has been cloned, and the mutation causing the disease is now known. We estimated the effect of FraX on dental development in 28 affected boys (aged 4.9-17.6 years) and three carrier girls (aged 5.8, 10.4, and 12.7 years). Dental maturity, assessed on the basis of formation [Demirjian A, Goldstein H. 1976: Ann Hum Biol 3:411-421] and of emergence [Hägg U, Taranger J. 1985: Angle Orthod 55:93-107], was compared with growth in stature and skeletal maturity. The mean relative dental age was advanced in FraX males, based on formation (+1.4 SD) and on emergence (+1.1 SD). More pronounced advancement was seen in younger children. Dental maturity was advanced in heterozygous carrier girls as well. Height and skeletal maturity did not show a similar trend toward advanced development.

Short root anomaly in families and its association with other dental anomalies

In the present study, we collected a family series with short root anomaly in order to analyze the inheritance pattern of the condition. Another aim was to identify in these families an association with other dental anomalies, such as tooth agenesis, peg-shaped lateral incisors, supernumeraries, ectopia, and such morphological characteristics as invaginations, taurodontism, and a tendency to root resorption. Mesiodistal dimensions of the crowns of the affected teeth were measured in order to reveal any association with reduction or increase in tooth size. The apparent genetic heterogeneity of the pedigrees did not permit definitive conclusions as to the mode of inheritance. Autosomal dominant transmission of short root anomaly was seen in 3/8 families. In 2/8 families, the condition was seen in siblings but not in parents. An association with tooth agenesis and ectopic canines was noted, the prevalences of which were 46% and 33%, respectively. We stress the importance of not misdiagnosing this anomaly as resorption.

Genetic craniofacial aberrations

Many craniofacial and dental anomalies have a genetic background. Much research related to the molecular pathology of genetic conditions is being carried out, and new information related to mapping of disease genes, gene identification, and mutations in these genes is accumulating with incredible speed. It is important to be well informed of the molecular background of the conditions that we treat at anomaly clinics. This article reviews the most recent molecular findings related to Turner syndrome, Beckwith-Wiedemann syndrome, Marfan syndrome, Treacher Collins syndrome, cleidocranial dysplasia, and cleft lip and palate.

Impaired oral health in patients with aspartylglucosaminuria

OBJECTIVE

The aim of this study was to assess the oral health of patients with aspartylglucosaminuria, a heritable lysosomal storage disorder, and to recommend guidelines for treatment.

STUDY DESIGN

Eighty-two patients with aspartylglucosaminuria and 122 control subjects were examined clinically; in addition, panoramic radiographs were evaluated in 61 patients with aspartylglucosaminuria and 61 control subjects.

RESULTS

High prevalences of caries, gingivitis, and oral Candida (P < .001), extensive gingival overgrowths (18%; P < .001), benign odontogenic tumors or tumorlike lesions (8%; P = .057), reduced maxillary sinuses (P < .001), limited mouth opening (P < .001), and food retention in the mouth (45%) were the major oral findings that distinguished the patients with aspartylglucosaminuria from the control subjects. Adults with aspartylglucosaminuria had diverse oral health problems, early loss of several permanent teeth being the most disabling feature.

CONCLUSIONS

Patients with aspartylglucosaminuria appear to be at a higher risk for a number of oral disorders; however, poor oral hygiene and failure to cooperate increase these patients' risk of dental and periodontal diseases, making successful prevention crucial.

Skeletal stability following mandibular advancement and rigid fixation with polylactide biodegradable screws

Skeletal stability during the first year after mandibular advancement surgery and fixation using biodegradable self-reinforced poly-l-lactide (SR-PLLA) screws, without postoperative intermaxillary fixation, was studied in 25 patients by means of cephalometric measurements. The magnitude of advancement was on average, 3.88 mm at pogonion (PG) (range 1.25-6.5 mm) and 4.57 mm at B-point (range 2.75-7.5 mm). After one year a mean relapse backwards of 0.59 mm at the PG (15%) and 0.78 mm at the B-point (17%) was observed. Nineteen patients (76%) and 17 patients (68%) were stable at PG and B-point, respectively. SR-PLLA screws are considered to be comparable to other forms of rigid internal fixation for fixation of bilateral splitting osteotomies after mandibular advancement, as far as skeletal stability is concerned.

Correlation between speech outcome and cephalometric dimensions in patients with diastrophic dysplasia

Diastrophic dysplasia (DTD) is a recessively inherited form of osteochondrodysplasia, presenting with disproportionate short stature and multiple orthopedic problems. The clinical oral manifestations include either cleft palate or submucous cleft palate in at least half of the patients. Histological studies have shown alterations in growth plate, articular, laryngeal, tracheal, and ear cartilages. Mutations in the DTDST gene, which codes for the sulphate transporter membrane protein, are responsible for the disease. Thirty-three patients were studied for speech characteristics and their correlation with cephalometric dimensions. Hyponasality was observed in 13 and misarticulation of /R/, /S/, or /L/ sounds in 17 of the 33 patients. Neither of these correlated with the occurrence of palatal deformities. Hyponasality was atypical and did not correlate with the obtained nasalance scores. Cephalometric measurements reflecting the size of the orofacial area of the vocal tract were short in the DTD patients compared with those in the healthy controls. The specific speech characteristics in DTD probably result from both the altered size and shape of the vocal tract and the structural and functional abnormalities of the laryngeal and tracheal cartilages.

Craniofacial structure in diastrophic dysplasia--a cephalometric study

Diastrophic dysplasia (DTD) is a well characterized, recessively inherited osteochondrodysplasia. Forty-eight patients with DTD were studied for craniofacial characteristics. Of these patients, 58% had cleft palate. A cephalometric analysis based on lateral cephalograms was performed. We observed a short anterior cranial base, vertical nasal bones, short and posteriorly positioned upper and lower jaws, increased anterior facial height, increase in the sagittal length of the body of the cervical vertebrae, and an abnormal dens of the second cervical vertebra. DTDST, in which mutations responsible for the disease occur, is a gene that codes for a sulphate transporter membrane protein. The craniofacial anomalies in DTD most likely result from deficient development and growth of cartilaginous structures and are probably due to defective sulfation of the proteoglycans of the cartilage.

Transverse facial morphology in patients with diastrophic dysplasia

Diastrophic dysplasia (DTD) is a well-characterized, recessively inherited osteochondrodysplasia. Thirty-seven patients were studied for transverse craniofacial characteristics. Of these patients, 10 had cleft palate and 11 had submucous cleft palate. A cephalometric analysis based on posteroanterior (PA) cephalograms was performed: 16 landmarks were identified and digitized into a computer. Seven linear and four angular variables were calculated and the values compared with those of a matched control population. DTD patients differed from controls only in cases with cleft palate where the mesio-orbital, bigonial, and antegonial widths were large compared with controls. The present findings indicate that although the development and growth of cartilaginous structures are disturbed in DTD, the intramembranously developing bones and the appositional growth pattern do not seem to be primarily affected.

The effect of violin playing on the bony facial structures in adolescents

Holding a violin between shoulder and chin needs a special kind of muscle function. The purpose of this investigation was to determine whether this kind of muscular activity is a modifying factor for facial growth in adolescence. The bony facial dimensions of 24 adolescent violin students attending colleges of music with a playing history of 5-11 years were measured from lateral and posteroanterior cephalograms and panoramic tomograms of the jaws. The dimensions were compared with those of sex- and age-matched controls. Significant differences were found between violin players and controls. The players had higher faces, especially on the right side of the lower face and in the right mandibular ramus. The players also had more proclined upper and lower incisors than the controls. It is concluded that the overall greater facial height in violinists reflects the increased face muscle activity and the higher bony dimensions of the right side of the face are due to the muscular activity produced on that side to balance the load caused by the violin on the left. The greater proclination of the incisors is the result of an altered balance of muscular activity between tongue and lip, and the pressure of the violin to the chin.

Characteristic dental arches and occlusion in patients with aspartylglucosaminuria

Aspartylglucosaminuria (AGU) is a lysosomal storage disorder with progressive mental retardation as a presenting manifestation. The disorder is caused by a single nucleotide change in the gene encoding aspartylglucosaminidase (AGA). This rare disease is relatively common in Finland: we were able to examine 81 Finnish AGU-patients for dental and oral changes. Tooth crown size and crown shape were normal, but dental malocclusions were common, and prevalences of spacing, large overjet, anterior open bite, and lateral crossbite exceeded Finnish population prevalences (P < 0.0001). Dental arches were already large in childhood, and in adult patients, when compared to Finnish population standards, the lower dental arch was larger in all dimensions (P < 0.001). Almost all patients had abnormally large tongues, which we assumed to be the reason for the structural abnormalities observed.

Periodontal findings in Cohen syndrome with chronic neutropenia

Radiographic periodontal status and microbiological findings of periodontal pockets in subjects with Cohen syndrome are presented in this report. This hereditary disorder causes mental retardation, and neutropenia is one feature of the syndrome. Fifteen patients with Cohen syndrome and 15 controls matched for age and sex and, as far as possible, according to the degree of mental retardation were examined. Alveolar bone loss was evaluated from the panoramic radiographs. Two subgingival samples were obtained from the most affected anterior and posterior periodontal sites in each dentate subject and examined for the occurrence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia/nigrescens, Peptostreptococcus micros, Bacteroides forsythus, and Campylobacter rectus. Subjects with Cohen syndrome had alveolar bone loss more frequently and the bone loss was more extensive (Mann-Whitney U-test: P < 0.05) than in the controls. They also harbored one or several of the putative periodontal pathogens (Mann-Whitney U-test: P < 0.001) more often than the controls. We conclude that subjects with Cohen syndrome have increased susceptibility to early periodontal breakdown which is likely to be associated with neutropenia.

The effect of professional violin and viola playing on the bony facial structures

Professional violin and viola playing involves a particular kind of asymmetric face, neck and shoulder muscle activity. The aim of this study was to find out whether players' facial morphology is influenced by this occupational orofacial muscle activity. Lateral and posteroanterior cephalograms and panoramic tomograms of 26 adult professional violin and viola players were evaluated and compared with those of age, sex and dentition matched controls. Significant differences were found between the players and the controls. The players had smaller facial heights, more proclined maxillary incisors and greater mandibular lengths. Thus, intense long-term violin/viola playing has the effect of modifying facial morphology.

Developmental dental defects associated with long breast feeding

Despite its unequivocal advantages, breast feeding may be associated with undesired side-effects. Recently, we have shown an association between exposure via mother's milk to dioxins and developmental defects of the child's teeth. The present study was undertaken to analyze further the association between the duration of breast feeding and the occurrence of dental defects. For this purpose, 2 different populations were selected. The first population comprised 40 children who had mineralization defects in the permanent 1st molars, and their age-living area- and sex-matched controls. The median duration of breast feeding was 9 months in the affected children compared to 6 months in the controls. The defects were more extensive after prolonged breast feeding. The second population consisted of 97 children whose mothers had been encouraged to extensive and prolonged breast feeding. Of these children, 24 had mineralization defects. They all had been breastfed longer than 8 months. In both study populations mineralization defects were associated with the duration of breast feeding. The result suggests that long breast feeding may increase the risk of mineralization defects in healthy children, possibly because of environmental contaminants that interfere with tooth development.

Palatal displacement of canine is genetic and related to congenital absence of teeth

The palatally displaced canine is a harmful complication of dental development. It appears in 1 to 2% of the Western population. According to our clinical experience, this anomaly is seen in families in which missing and peg-shaped teeth are common. It could be caused by the same genetic component that causes incisor-premolar hypodontia. We examined 106 patients who had been operated on and treated orthodontically for palatally impacted canine(s). The patients and their family members were examined for dental anomalies. One hundred and ten first- and 93 second-degree relatives were clinically and radiologically examined, and 35 pedigrees were constructed. Thirty-six percent of the patients had congenitally missing permanent teeth (hypodontia), which is 4.5 times the population prevalence. Hypodontia was noted in 19 to 20% of both the first- and second-degree relatives. This is 2.5 times the population prevalence. Frequency of missing teeth, analyzed by tooth groups, was of the same order as that shown for incisor-premolar hypodontia in the Western population. In six of the 35 pedigrees, a palatally impacted canine was noted in several generations of the same family. Prevalence of this anomaly was 4.9% in the studied group, which is 2.5 times the population prevalence. From the findings, we conclude that the palatally displaced canine belongs to the spectrum of dental abnormalities related to hypodontia.

Microanatomy of the dental enamel in autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED): report of three cases

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is an autosomal recessive disease composed of failure of various endocrine glands, chronic mucocutaneous candidiasis, and an ectodermal dystrophy complex including hypoplasia of the dental enamel. To characterize the enamel defect further, we studied enamel microanatomy by light microscopy and scanning electron microscopy in clinically affected permanent teeth from three APECED patients. In all three cases, the enamel was partially hypoplastic and morphologically aberrant. Hypoplasia was evident as a horizontal band or as rows of pits. The incremental pattern in the abnormal enamel was obscure, and the prisms were either barely detectable or accentuated and disoriented. In scanning electron microscopy, imprints of the Tomes processes were seen on the enamel surface, but the perikymata were poorly contoured. The distribution pattern of the defective enamel corresponded to the sequence of tooth development and was suggestive of a transient insult. In the enamel affected with a hypoplastic pitted from of amelogenesis imperfecta, studied for comparison, only local hypoplastic defects were seen. Together with normal parathyroid function in one patient and normal calcification of dentin in one of the two patients with hypoparathyroidism, morphology of the enamel in APECED appears to preclude calcium deficiency as the primary cause of the enamel dystrophy.

Phenotypic features of dentition in diastrophic dysplasia

Diastrophic dysplasia (DTD) is a well-characterized, recessively inherited osteochondrodysplasia. The gene, DTDST, in which mutations are responsible for the disease, codes for a sulphate transporter protein. We studied 53 patients with earlier diagnosed DTD for special characteristics in the oral region. Clinical examination included impressions of dental arches, oral photographs, and panoramic radiographs. Palatal clefting was recorded. Congenitally missing teeth were evaluated and dental maturity calculated from the panoramic radiographs. Tooth crown size and length and breadth of dental arches were measured from the casts. Dental anomalies and orthodontical status were evaluated from the casts and oral photographs. The level of oral hygiene was evaluated with caries (DMF) and periodontal (GBI) indices. Cleft palate was recorded in 56% and hypodontia (excluding third molars) in 31% of the patients. Dental age was retarded. Dental arches were narrow and tooth crown size was reduced. The observed crown size reduction could result from the same factors that cause cleft palate and/or hypodontia, or from a lack of sulfation in the developing dental papilla. The typical malocclusion traits were crowding, lateral crossbite, and open bite, which we assumed to result from reduced growth potential of the dental arches. Despite crowding and limited flexion of the finger joints leading to a severe handicap, the level of oral hygiene was high and no need for auxiliary equipment for cleaning the teeth was noted.

Gene defect in hypodontia: exclusion of EGF, EGFR, and FGF-3 as candidate genes

Hypodontia, congenital absence of one or a few permanent teeth without any systemic disorders, is regarded as an autosomally inherited dominant condition with varying expression and incomplete penetrance. Many studies have reported that the prevalence of hypodontia varies from 5% to 10% among European and Asian populations. The teeth most often missing are second premolars, upper lateral incisors, and lower central incisors. Consequently, we call this trait incisor-premolar hypodontia. Peg-shaped or strongly mesio-distally reduced upper lateral incisors demonstrate variation in the expression of the trait. The gene or genes causing incisorpremolar hypodontia are not known. We have begun the genetic mapping of hypodontia by using linkage analyses in seven Finnish three-generation families with 77 individuals, 31 affected with incisor-premolar hypodontia. As the first step, we studied the possibility of linkage between hypodontia and some candidate genes which have been suggested to have important functions during tooth development. Here we report the exclusion of EGF, EGFR, and FGF-3 loci as possible sites for gene mutation causing incisor-premolar hypodontia in our family material. Because of the close location of the FGF-3 and FGF-4 genes, the results also suggest the exclusion of the FGF-4 locus.

Gene defect in hypodontia: exclusion of MSX1 and MSX2 as candidate genes

Hypodontia, congenital lack of one or a few teeth, is an autosomally inherited dominant trait. Homeobox genes MSX1 and MSX2 are expressed in presumptive dental tissues at the stage of initiation of tooth development. Recently, tooth development was shown to be inhibited in transgenic mice lacking a functional Msx1 gene. Here, we studied the relationship of the MSX1 and MSX2 genes to familial hypodontia in five Finnish families with a total of 20 affected individuals, by linkage analysis. The pairwise lod-scores regarding the intragenic microsatellites in the MSX1 and MSX2 genes at a recombination fraction of 0.0 were -3.1 and -3.0, respectively, thus excluding these genes as causative loci for hypodontia in these families.

Endocrine regulation of craniofacial growth

This paper presents an updated review of the role of endocrine factors in craniofacial and dental development. Some unpublished results of the author's own studies are presented. Longitudinal growth studies have shown the similarity of facial and somatic growth rates, whereas dental development has been found to be independent. The increased therapeutic use of the growth hormone (GH) has focused attention on the dental and craniofacial effects of GH. Whereas delayed and advanced cranial base and facial growth is obvious in conditions with either lack or excess of GH, the effect of GH on the dentition is less clear. Thyroid hormones seem to be necessary for the eruptive movement of teeth. Sex steroids clearly have an effect on facial and cranial base growth and are also odontogenic, but the effects have not been much studied. The growth-inhibiting effect of corticosteroids is explained partly by the reduced response of cartilage cells to insulin-like growth factor-1. Experimentally, the effect is also seen in the condylar cartilage, but clinical studies have not been published. In tooth eruption an accelerating effect has been noted in experimental animals. The role of androgenic hormones in mandibular growth stimulation is discussed.

Craniofacial and dental characteristics of Silver-Russell syndrome

We found significant differences in a craniometric, cephalometric, and dental study of 19 Silver-Russell syndrome patients (13 without growth hormone treatment) with appropriate controls. Although head circumference was normal for age, head length was increased, while cranial and facial widths and facial heights were reduced. Posterior facial height, posterior cranial base length, cranial base height, and mandibular body size were significantly smaller than in healthy children of the same height. Articulatory speech disorders were common. Enamel defects pointed to an early prenatal insult. Delayed dental age and small mandibular and cranial base dimensions support the possibility of physiological growth hormone deficiency in many Silver-Russell syndrome children; however, facial soft tissue structures were strikingly different from those observed in classical growth hormone deficiency.

Craniofacial features in patients with deficient and excessive growth hormone

We studied the role of growth hormone (GH) in craniofacial growth by analyzing the craniofacial structures in patients with either deficient or excessive GH. The cephalogrammes of 21 patients with isolated or combined GH deficiency and of two patients with GH excess were compared with cephalogrammes of age and sex matched controls, and the patients with deficient GH also with height and sex matched controls. In cephalometric measurements, skeletal anatomy was followed as closely as possible. All patients had a Class I or an end-to-end dental occlusion. Head circumference was normal in all patients. Facial widths were significantly smaller in patients with deficient GH but at the level of + 2 SDs in the two with GH excess when compared to Finnish norms. In patients with deficient GH, facial heights were significantly smaller than in age matched controls, but of the same order with height controls for anterior facial height. Posterior facial height was smaller even in this comparison. In patients with GH excess, facial heights were much larger and at the levels of +3 and +6 SD. Clivus was shorter in patients with deficient GH and longer (+ 1.9 and +3 SD) in the two with GH excess. All angulations of the sphenoidal plane deviated from those of the controls in the group with GH deficiency. The cranial base angle (CL-SPhen) was smaller than in controls while it was normal in patients with GH excess. We are inclined to interpret the craniofacial structure of those with deficient GH as being unique to the condition rather than merely negative allometry.(ABSTRACT TRUNCATED AT 250 WORDS)