amelogenesis imperfecta ( ai ) is a diverse group of hereditary disorders that affect the quality and/or quantity of dental enamel . reduced enamel thickness , typically with normal hardness , is classified as hypoplastic ai , whereas reduced hardness , discoloration with normal thickness , is termed hypermineralized ai . in distal renal tubular acidosis ( drta ) , kidneys are unable to acidify the urine to ph < 5.5 in the presence of systemic metabolic acidosis or after acid loading as a result of impaired hydrogen ion secretion . in children , drta is most often a primary , hereditary condition and presents as hyperchloremic metabolic acidosis , hypokalemia , nephrocalcinosis / nephrolithiasis , polyuria , rickets , and growth retardation . early diagnosis of drta is critical so as to maximize growth with the treatment . bajpai et al . have reported that maximum catch - up growth occurs if drta is diagnosed and treated during the first 2 years of life . ai usually occurs alone but has been rarely reported in association with multiorgan syndromes such as cone - rod dystrophy , platyspondyly , nephrocalcinosis , hypothalamo  hypophyseal insufficiency , and kohlschutter syndrome . ai has also been rarely reported in association with metabolic disorders such as hypocalciuria , bartter - like syndrome , and dtra . in literature , only three cases of ai and drta have been described : two in adults and one in a child . here , we report a child with ai and dtra ; this is only second such case in pediatric age group . a 12-year - old girl was referred to the endocrine center at sher - i - kashmir institute of medical sciences , srinagar , jammu and kashmir , for evaluation of polyuria and short stature . from the age of 4 years she is the 5 of the six siblings born to native kashmiri consanguineous ( first cousins ) parents . her younger brother had died at the age of 4 years , and he had presented with hypokalemic quadriparesis . examination revealed prepubertal girl with severe , proportionate short stature ( height 117 cm , height standard deviation [ sd ] score  5.32 ) . oral examination revealed generalized pitting , yellowish - brown pigmentation of all the surfaces of the teeth , delayed exfoliation of deciduous teeth , and delayed eruption of permanent teeth [ figure 1 ] . radiographically , the radiodense enamel was absent in all the teeth with normal radiodensity of dentin , large , and open pulp canals . photograph of the patient showing generalized pitting , yellowish - brown pigmentation , and reduction of enamel thickness investigations revealed a normal anion gap metabolic acidosis ( serial serum ph 7.19 , 7.20 , and 7.22 and anion gap 11 , 14 , and 15 ) , alkaline urine ( serial urine ph 6.7 , 6.5 , and 7 ) , and hypokalemia ( serial serum k 1.85 , 1.52 , and 2.8 meq / l ) . routine lab investigations including blood glucose , serum calcium , serum phosphorus , alkaline phosphatase , thyroid function test , renal , and liver function tests were normal . urine analysis did not reveal glycosuria , proteinuria , or aminoaciduria indicating normal proximal tubular reabsorption . radiograph of left wrist did not show any evidence of rickets , and bone age was normal ( according to greulich and pyle atlas ) . renal ultrasonography showing bilateral nephrocalcinosis ( white arrows indicating nephrocalcinosis ) on the basis of persistent normal anion gap , metabolic acidosis with alkaline urine , hypokalemia , hypercalciuria , and bilateral nephrocalcinosis , a diagnosis of drta was made . the diagnosis was confirmed by ammonium chloride test , and the serial urine ph after oral intake of ammonium chloride was 7.3 , 7.5 , and 6.9 . we further investigated her for secondary causes of rta , and autoimmune profile including antinuclear antibody was negative . treatment with potassium citrate resulted in correction of hypokalemia , systemic acidosis , and marked relief of polyuria . the ai can be transmitted by an autosomal dominant , autosomal recessive , or x - linked mode of inheritance . mutations in five genes ( amelx , enam , klk4 , dlx3 , and mmp20 ) have been reported to cause ai . in children , drta is most often a primary inherited condition and can be essentially of three types : autosomal dominant drta ( the commonest form ) and autosomal recessive drta with and without sensorineural deafness . in autosomal recessive form , mutations involve subunits of the h - atpase proton pump while autosomal dominant form results from mutations involving the chloride - bicarbonate exchanger . metabolic acidosis due to rta can be differentiated from gastrointestinal loses on the basis of urine anion gap . in rta , ai has rarely been associated with renal parenchymal and renal tubular disorders such as bilateral nephrocalcinosis , hypocalciuria , impairment of renal concentration , hypokalemic metabolic alkalosis ( bartter - like syndrome ) , and impairment of urinary tubular acidification . this is a rare syndrome , and some of these cases can progress to renal insufficiency . the association of ai with rta is exceptionally rare , and till date , only two cases in adults and a solitary case in the pediatric age group have been reported . most of these cases including our case have been reported in consanguineous families , suggesting an autosomal recessive mode of inheritance . different renal proteins previously known to play a role in the systemic ph homeostasis in mammals have also been described to be expressed during amelogenesis : the carbonic anhydrase ii , acid  base exchangers ae2 , nbce1 , and nhe1 . h - atpase proton pump is expressed at high density on the luminal membrane of  intercalated cells of cortical collecting tubule . mutation of h - atpase proton pump is well known to cause autosomal recessive form of drta . there is a strong possibility that mutation of h - atpase proton pump can cause both ai and drta . on clinical grounds , there is a possibility that our patient may be harboring this mutation because only this mutation can explain the association of ai with drta . due to lack of facilities another hypothesis that may link ai with rta is that many of the dental proteins that were thought to be tissue - specific may also be expressed in nondental tissues such as renal tissues . for example , dlx3 , a homeobox protein , is also expressed in the kidney . further research concerning these proteins is necessary to determine whether they play a pivotal role in renal tubular disorders . severe cases characterized by a large number of nonerupted teeth need complete rehabilitation with overdentures . different renal proteins previously known to play a role in the systemic ph homeostasis in mammals have also been described to be expressed during amelogenesis : the carbonic anhydrase ii , acid  base exchangers ae2 , nbce1 , and nhe1 . h - atpase proton pump is expressed at high density on the luminal membrane of  intercalated cells of cortical collecting tubule . mutation of h - atpase proton pump is well known to cause autosomal recessive form of drta . there is a strong possibility that mutation of h - atpase proton pump can cause both ai and drta . on clinical grounds , there is a possibility that our patient may be harboring this mutation because only this mutation can explain the association of ai with drta . due to lack of facilities another hypothesis that may link ai with rta is that many of the dental proteins that were thought to be tissue - specific may also be expressed in nondental tissues such as renal tissues . for example , dlx3 , a homeobox protein , is also expressed in the kidney . further research concerning these proteins is necessary to determine whether they play a pivotal role in renal tubular disorders . severe cases characterized by a large number of nonerupted teeth need complete rehabilitation with overdentures . our report concerns a case of the rare syndrome of ai and drta and , hence , highlights the importance of detailed renal evaluation in patients with ai . an early diagnosis provided by the pathognomonic oral phenotype can lead to a better long - term renal prognosis . awareness of the possibility of such an association is very essential among dentists to ensure an early referral of these patients to physicians . to conclude , the present case highlights the importance of a thorough medical history , systemic examination , and detailed renal function tests including assessment of renal tubular functions in all patients with ai .
amelogenesis imperfecta ( ai ) is a heterogeneous group of inherited dental enamel defects . 
 it has rarely been reported in association with multiorgan syndromes and metabolic disorders . 
 the metabolic disorders that have been reported in association with ai include hypocalciuria , impaired urinary concentrating ability , and bartter - like syndrome . in literature , 
 only three cases of ai and distal renal tubular acidosis ( drta ) have been described : two cases in adults and a solitary case in the pediatric age group . here , we report a child with ai presenting with drta ; to the best of our knowledge , our reported case is the only second such case in pediatric age group . 
 our case highlights the importance of recognizing the possibility of renal abnormalities in patients with ai as it will affect the long - term prognosis .