FIG4 mutations leading to parkinsonism and a phenotypical continuum between CMT4J and Yunis Varón syndrome

BACKGROUND

Charcot-Marie-Tooth disease type 4J (CMT4J) originates from mutations in the FIG4 gene and leads to distal muscle weakness. Two null alleles of FIG4 cause Yunis Varón syndrome with severe central nervous system involvement, cleidocranial dysmorphism, absent thumbs and halluces and early death.

OBJECTIVES

To analyse the phenotypic spectrum of FIG4-related disease and explore effects of residual FIG4 protein.

METHODS

Phenotyping of five new patients with FIG4-related disease. Western Blot analyses of FIG4 from patient fibroblasts.

RESULTS

Next generation sequencing revealed compound heterozygous variants in FIG4 in five patients. All five patients presented with peripheral neuropathy, various degree of dysmorphism and a central nervous system involvement comprising Parkinsonism in 3/5 patients, cerebellar ataxia (1/5), spasticity of lower limbs (1/5), epilepsy (1/5) and/or cognitive deficits (2/5). Onset varied between the first and the seventh decade. There was no residual FIG4 protein detectable in fibroblasts of the four analysed patients.

CONCLUSION

This study extends the phenotypic spectrum of FIG4-related disease to Parkinsonism as a feature and demonstrates new phenotypes on a continuum between CMT4J and Yunis Varón syndrome.

[Tooth eruption disturbances and syndromes]

In the tooth eruption mechanism, various disturbances can appear as a result of gene mutations, a consequence of which can be that tooth eruption does not occur. There are 5 syndromes which involve the complete failure of several or even all teeth to erupt, specifically: cleidocranial dysplasia, Gardner's syndrome, osteopetrosis, mucopolysaccharidosis and GAPO syndrome. Some are very rare and will seldom be encountered in a dental practice, but they show how vulnerable the tooth eruption mechanism is. Dentists are generally the ones who identify a tooth eruption problem in a patient. Since syndromes can be associated with other disorders, additional investigation by a clinical geneticist is always important when a syndrome is suspected.

[A neonate without claviculae]

A 1-week-old girl, term born after a non-complicated parturition, presented with abnormal clavicles. At physical examination small and short clavicles were seen, as well as a widened anterior and posterior fontanelle. An X-ray of the thorax showed hypoplastic clavicles and an X-ray of the skull showed delayed ossification of the bones, hypoplasia of the maxilla and extra teeth. This led to the diagnosis 'cleidocranial dysplasia'.

Tooth eruption and cementum formation in the Runx2/Cbfa1 heterozygous mouse

Cleidocranial dysplasia (CCD) is an autosomal dominant human disorder that affects development of bones and teeth. The dental disorders in CCD patients include formation of supernumerary teeth, delayed tooth eruption, and lack of formation of cellular cementum in permanent teeth. This disorder involves a mutation in the osteoblast-specific transcription factor Runx2/Cbfa1, leading to haploinsufficiency of the Runx2/Cbfa1 protein. Here, we examined if Runx2/Cbfa1 heterozygous mice (with one functional allele for Runx2/Cbfa1) exhibit similar changes in tooth eruption, and dental cementum formation as in CCD patients. Heads of Runx2/Cbfa1 heterogeneous and wildtype mice aged days 16-35 postnatally were serially sectioned and stained with hematoxylin-eosin or for tartrate resistant acid phosphatase (TRAP) to identify osteoclasts. The results showed that the eruption pattern of the first and second molars in maxilla and mandible in Runx2/Cbfa1 +/- mice was the same as in wildtype animals. No clear difference in distribution or in the (estimated) number of osteoclasts was found. Cellular cement at the apical portions of the molar roots was present in both groups. The data suggests that in the mouse one allele for Runx2/Cbfa1 is sufficient for an undisturbed tooth eruption and an apparently normal formation of the periodontium.

Cleidocranial dysplasia with decreased bone density and biochemical findings of hypophosphatasia

Cleidocranial dysplasia (CCD; MIM 119600) is an autosomal dominant skeletal dysplasia characterised by hypoplastic clavicles, patent fontanelles, short stature, tooth anomalies and other variable skeletal changes. Different mutations of the RUNX2/CBFA1 gene (MIM 600211) have been detected in patients with CCD. We investigated a mother and daughter with features of CCD presenting with reduced plasma alkaline phosphatase activity, increased urinary phosphoethanolamine excretion and decreased bone density. The latter findings were suggestive of hypophophatasia but mutation analysis showed no mutation in the tissue-nonspecific alkaline phosphatase gene (TNSALP; MIM 171760). However, a heterozygous mutation (Arg169Pro caused by nucleotide change 506G > C) was detected in the RUNX2 gene. Metabolic alterations gradually improved in both mother and daughter but bone-specific alkaline phosphatase remained low (less than 30% of normal) and mild phosphoethanolaminuria persisted. Recent studies in the Cbfa1 knock-out mouse showed decreased expression of alkaline phosphatase in differentiating bone.

CONCLUSION

we suggest that the observed metabolic alterations are secondary to the RUNX2 gene mutation affecting early bone maturation and turnover. This is the first description of biochemical findings of hypophosphatasia in patients with cleidocranial dysplasia.

Delayed dental maturation in cleidocranial dysplasia

Cleidocranial dysplasia (CCD), a rare, inherited, generalized, skeletal and dental dysplasia, exhibiting an autosomal dominant mode of transmission, may be associated with delays during tooth maturation. To test whether permanent tooth formation is delayed in patients with CCD and if the presence of supernumerary teeth adversely influences maturation of the dentition, a group of CCD patients (eight females, three males) was compared to an equal number of control subjects matched for age and gender. Dental maturity was assessed using panoramic radiographs and the Dental Maturity Ratio, (DMR = mean dental age divided by the chronological age) was calculated. The mean DMR in CCD patients (0.87 +/- 0.14) was lower than in the control group (1.06 +/- 0.14), p < 0.01. Among patients with CCD, patients with supernumerary teeth, had a lower DMR (0.82 +/- 0.13 vs. 0.91 +/- 0.16), but the difference did not reach statistical significance. After adjusting for the presence of supernumerary teeth the diagnosis of CCD was still found to be associated with lower DMR than controls, p = 0.0569. We conclude that CCD patients have delayed tooth development of approximately 2.1 years and that among these patients, those with supernumerary teeth were further delayed by 1.5 years.

[Syndromes. 1. Cleidocranial dysplasia]

Dysostosis cleido-cranialis is mainly characterized by a pathognomonic deformity of the skull, a hypoplastic midface, lack of eruption of permanent teeth, supernumerary teeth, defects in the clavicles, short stature and multiple other skeletal deformities. The inheritance is autosomal dominant, but there is a considerable number of new mutations.

Characteristics of jaw growth in cleidocranial dysplasia

OBJECTIVE

The purpose of this pilot study was to assess craniofacial morphology in young and adult individuals with cleidocranial dysplasia (CCD).

DESIGN

Craniofacial morphology in young individuals (primary dentition) and in young adults was compared with control data using ratios and angles obtained from lateral head films.

SETTING

The CCD individuals were referred to the Center for Craniofacial Anomalies for diagnostic workup and treatment recommendations.

SUBJECTS

The sample consisted of 14 Caucasians. The inclusion criterion for the young, prepubertal group (A) was complete primary dentition, and for the adult, postpubertal group (B), the eruption of all four first molars was required.

INTERVENTIONS

No treatment other than extraction or surgical removal of selected primary or supernumerary teeth was performed.

RESULTS

Both groups showed significantly smaller anterior upper face height compared with controls. Group B subjects demonstrated significantly smaller face height values than the controls in the A point-nasion-B point (ANB) angle, facial axis, mandibular plane angle, palatal plane/mandibular plane angle, and gonial angle. No significant differences were found between group A individuals and the controls for these measurements. The older group had shorter anterior lower face height compared with both anterior upper face height and posterior lower face height.

CONCLUSIONS

Whereas young CCD subjects showed relatively normal jaw proportions and morphology of the mandible, older CCD individuals tended to have short lower face height, acute gonial angle, anterior inclination of the mandible, and mandibular prognathism. These differences can be attributed to pronounced horizontal mandibular growth resulting from lack of vertical maxillary growth and impaired eruption of permanent teeth.

[Cleidocranial dysplasia: a case report]

A 3-month-old female infant who presented with patent sagittal suture and loss of weight is described. Physical examination revealed a large sagittal and metopic suture showing delayed closure, a high-arched palate, saddle nose, hypertelorism and nonpalpable edges of the bilateral clavicles. The clavicles also showed undue mobility. Radiological investigations of the cranial skeletal abnormalities revealed enlargement of the sagittal and metopic sutures, and the anterior and posterior fontanelles. A chest radiograph showed a small, bell-shaped thoracic rib cage with partial aplasia of both clavicles. On the basis of the clinical findings, cleidocranial dysplasia was diagnosed. Cleidocranial dysplasia is an uncommon generalized skeletal disorder which, as its name implies, shows striking involvement of the cranial vault and clavicles. The clinical features reflect a generalized defect of both membranous and endochondral bone formation. It is characterized by delayed ossification of the skull, aplastic or hypoplastic clavicles, delayed deciduous dentition, and hereditary characteristics. The amount of calvarial growth is generally small, and the shape remains nearly unaltered. In all cases, calvarial bone thickness increases with age, but in the midline, the fontanelle area, which is shown to be defective at the first examination, remains open in all cases. The midfrontal area is poorly developed and exhibits a groove in many patients. It is inherited as an autosomal dominant trait, with wide variability of expression but a high degree of penetrance. Cytogenetic abnormalities involving chromosome 6p21 have been reported with a cleidocranial dysplasia phenotype. Although psychosocial disorders associated with the abnormal facial and body features may occur, patients have a good overall prognosis and life expectancy. Skull deformity, and delayed closure of the fontanelles and cranial sutures are the most important problems for neurosurgeons. The postero-lateral fontanelle closes before adulthood, whereas the opening in the midfrontal sutural area may persist. Many children with cleidocranial dysplasia whom we have encountered have persisting fontanelles and patent sutures, but this does not seem to predispose them to an abnormal calvarial growth pattern, at least in the age groups investigated. Congenital midface retrusion in the presence of relative or absolute mandibular prognathism is also a major deformity. Care is supportive, including attention to neurosurgical, orthopedic, pediatric and dental problems.

Dental development and molar root length in children with cleidocranial dysplasia

Cleidocranial dysplasia (CD) is an autosomal dominant skeletal disorder with characteristic dental findings of numerous supernumerary teeth and noneruption of permanent teeth. This investigation compared the dental development and root lengths of the mandibular first permanent molar in 11 CD patients with those of 22 healthy, normal children matched for race, age and sex. The results showed that children with CD experienced a delay in dental development of approximately 3 years compared with normal children (P < 0.05). In addition, the root lengths of the mandibular first permanent molar were significantly longer than those of the comparison children (17.8 +/- 1.6 mm vs 13.6 +/- 1.2 mm (P < 0.001). This study thus revealed two significant clinical features of CD: 1) severe delay in dental development, and 2) excessive root lengths of mandibular permanent first molars. These features may be important in the pathogenesis of delayed dental eruption observed in this disorder.

[Cleidocranial dysplasia: review of the literature and presentation of a case]

Cleidocranial Dysplasia, although not frequent, can present to the dentist. In this article, we have reviewed the literature concerning this disease and we present a patient with this condition. An overview of the disease would reveal partial to complete absence of clavicles, delayed closing of cranial fontanels, prolonged retention of deciduous teeth, subsequent delay in eruption of permanent teeth and multiple impactions.

Facial and dental anomalies in cleidocranial dysplasia: a study of 17 cases

Seventeen cases of cleidocranial dysplasia were analysed. On average, there was mandibular prognathism due to increased mandibular length, and a short cranial base. The maxilla was short vertically but not antero-posteriorly. In 13 young subjects followed for an average period of 6 years, more than half of the total number of teeth of each type had not erupted at the normal age, with the exception of mandibular incisors. Twice as many maxillary incisors were delayed compared with those in the lower jaw. Only six of 25 mandibular central incisors were delayed. There was a total of 63 supernumerary teeth in the 13 subjects, mostly occurring in the mandibular premolar and maxillary incisor regions. Many more occurred in the maxillary than in the mandibular incisor region. In the molar regions only six supernumerary teeth were found, five in the upper jaw and one in the lower. Two patients had no supernumerary teeth. One patient showed congenital absence of one mandibular incisor and three premolars.

Abnormal ossification of the hyoid bone in cleidocranial dysplasia

Radiographs of the hyoid region of 13 patients with cleidocranial dysplasia were reviewed. In all but one the hyoid bone was less ossified than normal. Delayed ossification, affecting the skull, the teeth, the pelvis and the extremities, is a known, frequent manifestation of this abnormality.

Development of the skull in infants with cleidocranial dysplasia

The purpose of the present paper is to clarify some of the questions regarding pathogenesis in cleidocranial dysplasia (CCD) in order to improve the understanding of the mechanisms leading to the craniofacial abnormalities characteristic for young and adult patients with the syndrome. The neonatal skull is described and craniofacial development from birth to 7 years analyzed. Skull radiographs of 11 CCD patients ages 0-7 years were examined. Study methods included plain radiographs of the skull and roentgencephalometric films in the lateral, frontal, and axial projections. In one patient, CT scans of the skull with 3-D reconstructions were available. Common to the four patients examined within the first 6 months postnatally was a marked delay of skeletal maturity. In the calvaria a severe reduction of calcification in all bones was found. Corresponding to the expected sutural areas, gaping defects were recorded, indicating that calcification of calvarial bones in the newborn CCD individual had only reached a stage corresponding to around 20 weeks gestational age. Calvarial size corresponded to that of normal newborns and the morphology was relatively normal, taking into account the pronounced deformation that took place during parturition due to the soft, undermineralized skull. At birth bony islands could be observed in the periphery of the occipital, parietal, and frontal bones. Ossification of the maxilla and the mandible seemed to be within normal limits. Posteriorly to the foramen magnum, the chondral part of the supraoccipital bone remained unossified. In the cranial base an increased width of the spheno-occipital synchondrosis was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Craniofacial abnormalities in 52 school-age and adult patients with cleidocranial dysplasia

The purpose of the present investigation is to describe and discuss the craniofacial abnormalities in young and adult patients with cleidocranial dysplasia (CCD). Skull radiographs of 52 CCD patients were examined. Thirty-six patients were adult, 16 were between 7 and 16 years old. Facial photographs were available in 30 cases, and in one adult case with cranial CT scans, 3-D reconstructions were carried out. High quality photographs of six CCD skulls were also described. The paranasal sinuses were absent or diminished in all children and most adult patients. An inverted pear-shape of the calvaria and an open anterior fontanelle were present in more than 60% of the cases. In the cranial base an upward distortion of the clivus, an anteverted foramen magnum, and extremely narrow choanae were frequent traits, together with small sella and bulbous dorsum sellae. Nearly all patients and dry skulls showed hypoplasia or absence of nasal bones. The zygomatic arches were diminished or incomplete in all cases. Mandibular morphology was judged to be syndrome specific with the slender, upward-backward-pointing coronoid process. We have concluded that a great part of the abnormal qualitative traits are present to a lesser degree in CCD children, indicating a progressive abnormal development with advancing age. From the present and previous studies on CCD we have hypothesized that on top of their generalized reduction of growth potential, these patients suffer from a combination of skeletal immaturity resulting in deformations and a defective bone remodeling. We have acknowledged the importance of longitudinal investigations in order to ameliorate the understanding of the pathogenesis of CCD and thereby to improve total patient care. Correction of the craniofacial abnormalities may be advocated in the most severe cases of hypertelorism and midfrontal groove, if psychosocial problems occur. Also, patients with major midface underdevelopment might benefit from combined orthodontic/surgical correction.

Dental treatment strategies in cleidocranial dysplasia

Based on the findings of our recent longitudinal study on the abnormalities of the dentition in cleidocranial dysplasia (CCD), a hypothesis has been proposed, which makes it possible to predict time of onset of formation of supernumerary teeth and their location in the jaws. It was found that a diagnosis should be made early so that formation of supernumerary teeth can be diagnosed and early intervention undertaken. It should be possible to diagnose supernumerary incisors at about 5-7 years of age and supernumerary canines and premolars a few years later. When root length of the normal permanent teeth has reached about one third of its final length, the overlying supernumerary teeth should be removed, together with overlying bone and primary teeth. In regions where no supernumerary teeth are formed, eruption may also be improved by removal of the primary teeth and surgical exposure of the underlying permanent teeth. Conventional orthodontic treatment and eventually autotransplantation of teeth may still be necessary in the future, but it can be anticipated that the new strategy, with much earlier intervention, will materially reduce the extent of surgical and orthodontic interventions, which have previously been of extremely long duration, tedious to the patients and often of limited success.

[Development of the dentition in cleidocranial dysplasia]

The purpose of the present investigation was to describe the formation, maturation and eruption of the dentition, including supernumerary teeth in a sample of patients with cleidocranial dysplasia. The dentition was evaluated from orthopantomograms, intraoral radiographs, cephalometric films, surgically removed teeth and intraoral photographs in 22 patients (10 men, 12 women), aged 3.5 to 34 years. Formation of primary teeth was normal, whereas all patients but one had supernumerary permanent teeth. Frequency of supernumerary teeth ranged from 22% in the maxillary incisor region to 5% in the molar regions. Anterior to the molar region supernumerary teeth were formed lingually and occlusally to the normal teeth. Maturation of the primary dentition was normal, while permanent teeth were delayed from 1 to 4 years. Supernumerary teeth were delayed about 4 years in relation to normal permanent teeth. Eruption of primary teeth was normal, whereas all patients had severe eruption problems of permanent teeth.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of the dentition in cleidocranial dysplasia

The purpose of the present investigation was to describe the formation, maturation and eruption of the dentition, including supernumerary teeth in a sample of patients with cleidocranial dysplasia. The dentition was evaluated from orthopantomograms, intraoral radiographs, cephalometric films, surgically removed teeth and intraoral photographs in 19 patients (9 men, 10 women), aged 3.5 to 34 years. Formation of primary teeth was normal, whereas all patients but one had supernumerary permanent teeth. Frequency of supernumerary teeth ranged from 22% in the maxillary incisor region to 5% in the molar regions. Supernumerary teeth were formed lingually and occlusally to the normal teeth. Maturation of the primary dentition was normal, while permanent teeth were delayed from 1 to 4 yr. Supernumerary teeth were delayed about 4 years in relation to normal permanent teeth. Eruption of primary teeth was normal, whereas all patients had severe eruption problems of permanent teeth. It was hypothesized that the dental lamina for both primary and permanent dentition is normal, but does not resolve completely and therefore may form supernumerary teeth. Abnormalities of tooth morphology is related to inadequate space and arrested eruption. Delayed or arrested eruption is probably caused by diminished resorption of bone and of primary teeth and to the presence of multiple supernumerary teeth.

Somatic development in cleidocranial dysplasia

As part of a more comprehensive investigation of general and craniofacial development in cleidocranial dysplasia (CCD), the present study describes general somatic development and analyzes longitudinal growth of 17 patients (seven males, ten females, aged 5-46 years) with CCD. Eleven were followed longitudinally. Data included family history, anthropometric measurements, and radiographs of the right hand and forearm. Height and radius length were significantly decreased, being most pronounced in females. The longitudinal growth data showed growth retardation and slightly retarded skeletal maturity throughout childhood. Metacarpophalangeal pattern profile analysis demonstrated great variation in bone lengths, presumably resulting from extra epiphyses in the 2nd and 5th metacarpals and from multiple cone-shaped epiphyses. Findings of the present study support the view that CCD is a generalized skeletal dysplasia.

Large electroencephalographic responses and their relationship to cleido-cranial dysplasia

We have reported six individuals (five certain heterozygotes for cleido-cranial-dysostosis and one possible heterozygote) who have unusual EEG findings, consisting of very large responses to photic flash stimulation at very low stimulus rates. Such visual responses are extremely rare and have not been seen before in the experience of an EEG department over 12 years and they were not seen in 98 control subjects. It is likely that these responses are an irregular manifestation of the gene for cleido-cranial-dysplasia, and that the responses are independent of skull deformity. One importance of these responses is their demonstration in neurologically normal individuals for previously such large responses have only been reported in association with neurolipidosis. They may have neurophysiological significance in that they may reflect an unusual balance between inhibitory and excitatory mechanisms in the nervous system.