|Year : 2012 | Volume
| Issue : 2 | Page : 169-172
Enamel renal syndrome: A rare case report
SV Kala Vani1, M Varsha2, Y Uday Sankar3
1 Department of Orthodontics and Dentofacial Orthopedics, C. K. S. Teja Institutions of Dental Sciences, Tirupati, Andhra Pradesh, India
2 Department of Pedodontics, C. K. S. Teja Institutions of Dental Sciences, Tirupati, Andhra Pradesh, India
3 Department of Oral Medicine and Radiology, C. K. S. Teja Institutions of Dental Sciences, Tirupati, Andhra Pradesh, India
|Date of Web Publication||23-Aug-2012|
S V Kala Vani
Department, of Orthodontics and Dentofacial Orthopedics, C. K. S. Teja Institutions of Dental Sciences, Tirupati,Andhra Pradesh
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Enamel renal syndrome is a very rare disorder associating amelogenesis imperfecta with nephrocalcinosis. It is known by various synonyms such as amelogenesis imperfecta nephrocalcinosis syndrome, MacGibbon syndrome, Lubinsky syndrome, and Lubinsky-MacGibbon syndrome. It is characterized by enamel agenesis and medullary nephrocalcinosis. This paper describes enamel renal syndrome in a female patient born in a consanguineous family.
Keywords: Amelogenesis imperfecta, delayed eruption, enamel renal syndrome, nephrocalcinosis; renal ultrasound
|How to cite this article:|
Kala Vani S V, Varsha M, Sankar Y U. Enamel renal syndrome: A rare case report. J Indian Soc Pedod Prev Dent 2012;30:169-72
| Introduction|| |
Enamel-renal syndrome (ERS, OMIM 204690) is characterized by hypoplastic amelogenesis imperfecta (AI) and nephrocalcinosis (NC). It is listed as a "rare disease" by the office of rare diseases (ORD) of the National Institutes of Health (NIH). This means ERS affects less than 200,000 people in the US population. The common features of this syndrome are the presence of thin or no enamel, delayed tooth eruption, intrapulpal calcifications, bilateral nephrocalcinosis, and normal plasma calcium.
Amelogenesis imperfecta is a heterogeneous group of conditions, genomic in origin, which affects the structure and clinical appearance of the enamel of all or nearly all the teeth in a more or less equal manner and which may be associated with morphologic or biochemical changes elsewhere in the body.  It occurs with a frequency of 1 : 700  to 1 : 14000  as an isolated defect. It shows autosomal dominant, autosomal recessive, x-Linked and sporadic inheritance patterns. The enamel may be hypoplastic, hypomineralized, or hypomature, depending on the clinical presentation of the defects and the likely stage of enamel formation that is primarily affected.
Although AI is generally considered to primarily affect the dental enamel, other oral and dental stigmata including delayed tooth eruption, unerupted teeth, anterior open bite, pulpal calcifications, inter-radicular dentinal dysplasia, intracoronal resorption, taurodontism have been shown to co-exist. , In addition, it is a feature of several multiorgan syndrome but pathognomonic of only a few. ,,,
In the past 30 years, an extremely rare syndrome associating AI with NC has been reported in just a few families. ,,,,,,,,, Nephrocalcinosis is a common disease characterized by the precipitation of calcium salts in the renal tissue. In the patients with ERS, the impaired renal function is variable or delayed to adulthood despite the presence of typical renal hyperechogenicity in childhood. The relation between the enamel defect and NC is still unknown.
| Case Report|| |
A 11-year-old female patient presented with failure of eruption of upper and lower permanent teeth. Apart from the consanguineous marriage, her parents had past dental and medical history was noncontributory. There was no family history of either AI or failure of eruption of permanent teeth and her elder male sibling showed normal dental development. Her general, physical, and clinical findings were normal.
On intraoral examination, it was found that all deciduous teeth were retained and exhibited advanced wear, the molars being devoid of any cuspal features. The permanent mandibular first molars have erupted and permanent maxillary first molars are erupting. The retained deciduous teeth and permanent first molars showed yellow discoloration. Severe attrition resulted in anterior open bite [Figure 1].
|Figure 1: Intraoral photographs showing enamel discoloration, marked attrition, and anterior openbite. (a) Frontal view, (b) right lateral view,(c) left lateral view, (d) maxillary occlusal view, (e) mandibular occlusal view|
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The panoramic radiograph [Figure 2] showed all permanent teeth including third molars. All the permanent teeth showed delayed eruption. The contrast between enamel and dentine was reduced indicating low mineral content of enamel. Intrapulpal calcifications were limited to some primary and permanent teeth.
|Figure 2: Orthopantomogram revealing multiple unerupted permanent teeth with lack of contrast between enamel and dentine and intracoronal pulp calcifications in deciduous and unerupted permanent teeth. Black arrows indicating intracoronal pulp calcifications|
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The ultrasound examination of her kidneys and bladder [Figure 3] demonstrated multiple hyperechoic foci with posterior acoustic shadowing in all the medulla in both kidneys suggestive of bilateral nephrocalcinosis. The size of the kidneys was normal and there were no urinary tract abnormalities. No other relevant renal history was present.
The serum biochemical markers and hematological parameters were all in the normal range. No abnormalities were detected in her endocrinal profile, which would exclude the involvement of metabolic hard tissue disease. Her renal function tests showed normal blood urea (3.82 mmol /L), normal serum creatinine (61.88 μmol/L), normal creatinine clearance (1.90 mL/s), normal serum electrolytes (Na: 140 mmol/L, K: 4.9 mmol/L, Cl: 105 mmol/L), and normal blood gas findings (HCO3 --- : 22 mmol/L). Twenty-four-hour urinalysis revealed normal urine creatinine (6.0 mmol/ day), normal protein (0.064 g/ day), hypocalciuria (0.575 mmol/ day; normal: 1.25-6.25 mmol/day) and low urine phosphate levels (1.0 mmol/day; normal: 15-50 mmol/day). Fractional excretion of calcium also has reduced (0.8%; normal: 1%).
| Discussion|| |
The syndrome of ERS has been previously described in 15 cases ,,,,,,,,, from consanguineous as well as nonconsanguineous families. All cases had thin or absent enamel and bilateral NC. While some cases progressed to renal insufficiency, ,,,, others featured certain renal tubular disorders. ,,,, Some cases reported association of this syndrome with other renal disorders such as polycystic kidney disease and distal renal tubular acidosis. 
In the present case, NC was detected after the clinical and radiological diagnosis of AI. Nephrocalcinosis may remain undetected until patients present with recurrent urinary tract infections, pyelonephritis, or passage of a stone. In these conditions, the ultrasound appearance of NC are indistinguishable from other causes of medullary NC. In the course of preparation of this case for paper presentation, we conducted an electronic literature search on the keywords AI and delayed eruption. This revealed an extremely rare association of AI with NC. As a precautionary measure, she was referred to a radiologist for ultrasound examination of kidneys and bladder that revealed bilateral medullary NC. The consanguineous marriage of the patient's parents suggests an autosomal recessive inheritance in this condition. Out of different forms of AI, hypoplastic type is frequently associated with this syndrome.  Kirzioglu et al.  analyzed the prevalence of NC in AI patients by renal ultrasound, revealing suspicious radiopacities in one out of five patients with a diagnosis of AI. Interestingly, all patients with evidence of NC were classified as the hypoplastic type of AI.
Delayed tooth eruption exhibited by this patient was in its most severe form with only permanent mandibular first molars erupted unlike other cases reported on ERS. ,,,,,, Seow  reported that tendency towards delayed eruption in AI patients was six times that of unaffected individuals and the most severe cases occurring in autosomal recessive hypoplastic AI.  Earlier studies suggested that delay of eruption could be due to pathology of dental follicle. ,,
Intrapulpal calcifications as revealed by panoramic film of this patient is frequently exhibited by autosomal recessive hypoplastic AI. Cosegregation of delayed tooth eruption, pulp calcification, and hypoplastic enamel has been first reported by Peters et al. and strongly suggests that the mutation causing this AI type involves a gene expressed in ameloblasts as well as in other odontogenic tissues. The association of ERS with this triad has been reported previously. ,,,,, Gingival enlargement and intracoronal resorption have also been reported ,,,,, but were not seen in this case.
Concerning the renal pathology, NC remains unexplained. In ERS syndrome, no predisposing factors such as hypercalcemia, hypercalciuria have been found. On the contrary hypocalciuria, ,, low phosphate in urine , and proteinuria , have been reported . Our patient also has low urinary calcium and phosphate with normal urinary proteins. It remains unclear whether these are the cause or consequence of this syndrome or whether it may be involved in the nephrocalcinosis. Cases so far reported, suggest that there is no abnormality of bone metabolism.
Histologically detectable NC has been reported as an incidental finding in upto 100% of autopsies. Radiographically detectable NC is much less common.  This syndrome therefore seems to combine one uncommon condition (AI) with one much less common (NC). Although rare syndrome untreated NC is known to be associated with significant morbidity.
Paradigms behind the etiopathogenesis of ERS include pleotrophism,  abnormality in interstitial matrix leading to dystrophic calcification,  expression of tissue specific dental proteins in dental and nondental tissues, , and symbiotic role of albumin and osteopontin. , Significant progress has to be made to define the genetic defect behind ERS and further research is needed to clarify the pathogenesis of AI and NC.
Though, often asymptomatic NC can be associated or can lead to the impaired renal function. It is mandatory to alert the dentists who see children with generalized hypoplastic AI, should obtain a detailed family history and past medical history with particular reference to urinary tract and should be referred for medical examination including renal function tests and ultrasonography to detect NC. Similarly, awareness must be created among nephrologists to recommend oral examination in children with unexplained NC associated with unusual appearance of teeth.
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[Figure 1], [Figure 2], [Figure 3]
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