[The 475th case: renal tubular acidosis, renal failure, anemia, and lactic acidosis].

A 47-year-old female patient presented nausea and vomiting for half a year and elevated serum creatinine for 3 days. Proximal renal tubular acidosis (RTA) complicated with anemiawas confirmed after admission. Secondary factors, such as autoimmune disease, drugs, poison, monoclonal gammopathy, were excluded. Renal biopsy revealed acute interstitial nephritis. The patient was administrated with daily prednisone 50 mg, sodium bicarbonate 4 g, 3 times per day, erythropoietin 3 000 U, 2 times per week, combined with potassium, calcium, and calcitriol tablets. Serum creatinine reduced to 90 µmol/L. However nausea and vomiting deteriorated with lactic acidosis. Bone marrow biopsy indicated the diagnosis of non-Hodgkin lymphoma, therefore the patient was treated with chemotherapy. Although metabolic acidosis improved gradually after chemotherapy, severe pneumocystis carinii pneumonia developed two weeks later. The patient refused further treatment and was discharged.

Proteomic Profiling of the First Human Dental Pulp Mesenchymal Stem/Stromal Cells from Carbonic Anhydrase II Deficiency Osteopetrosis Patients.

Osteopetrosis is a hereditary disorder characterized by sclerotic, thick, weak, and brittle bone. The biological behavior of mesenchymal cells obtained from osteopetrosis patients has not been well-studied. Isolated mesenchymal stem/stromal cells from dental pulp (DP-MSSCs) of recently extracted deciduous teeth from osteopetrosis (OP) patients and healthy controls (HCs) were compared. We evaluated whether the dental pulp of OP patients has a population of MSSCs with similar multilineage differentiation capability to DP-MSSCs of healthy subjects. Stem/progenitor cells were characterized using immunohistochemistry, flow cytometry, and proteomics. Our DP-MSSCs were strongly positive for CD44, CD73, CD105, and CD90. DP-MSSCs obtained from HC subjects and OP patients showed similar patterns of proliferation and differentiation as well as gene expression. Proteomic analysis identified 1499 unique proteins with 94.3% similarity in global protein fingerprints of HCs and OP patients. Interestingly, we observed subtle differences in expressed proteins of osteopetrosis disease-related in pathways, including MAPK, ERK 1/2, PI3K, and integrin, rather than in the stem cell signaling network. Our findings of similar protein expression signatures in DP-MSSCs of HC and OP patients are of paramount interest, and further in vivo validation study is needed. There is the possibility that OP patients could have their exfoliating deciduous teeth banked for future use in regenerative dentistry.

Oral manifestations of renal tubular acidosis associated with secondary rickets: case report / Manifestações bucais da acidose tubular renal associada ao raquitismo secundário: relato de caso

ABSTRACT This report describes the oral manifestations of renal tubular acidosis (RTA) associated with secondary rickets and discusses the biological plausibility of these findings. The characteristic electrolyte changes during RTA or genetic mutations that trigger RTA may be responsible for impaired amelogenesis, dental malocclusion, impacted teeth, and absent lamina dura. This report reinforces the possibility of an association between RTA and the oral manifestations described.

RESUMO Este relato de caso descreve as manifestações bucais da acidose tubular renal (ATR) associada ao raquitismo secundário e discute a plausibilidade biológica desses achados. As alterações eletrolíticas características da ATR ou as mutações genéticas que a desencadeiam podem ser responsáveis pela amelogênese imperfeita, maloclusão dentária, dentes impactados e ausência de lâmina dura. Este relato reforça a possibilidade de uma associação entre ATR e as manifestações bucais descritas.

Molecular mechanisms of cutis laxa- and distal renal tubular acidosis-causing mutations in V-ATPase a subunits, ATP6V0A2 and ATP6V0A4.

The a subunit is the largest of 15 different subunits that make up the vacuolar H+-ATPase (V-ATPase) complex, where it functions in proton translocation. In mammals, this subunit has four paralogous isoforms, a1-a4, which may encode signals for targeting assembled V-ATPases to specific intracellular locations. Despite the functional importance of the a subunit, its structure remains controversial. By studying molecular mechanisms of human disease-causing missense mutations within a subunit isoforms, we may identify domains critical for V-ATPase targeting, activity and/or regulation. cDNA-encoded FLAG-tagged human wildtype ATP6V0A2 (a2) and ATP6V0A4 (a4) subunits and their mutants, a2P405L (causing cutis laxa), and a4R449H and a4G820R (causing renal tubular acidosis, dRTA), were transiently expressed in HEK 293 cells. N-Glycosylation was assessed using endoglycosidases, revealing that a2P405L, a4R449H, and a4G820R were fully N-glycosylated. Cycloheximide (CHX) chase assays revealed that a2P405L and a4R449H were unstable relative to wildtype. a4R449H was degraded predominantly in the proteasomal pathway, whereas a2P405L was degraded in both proteasomal and lysosomal pathways. Immunofluorescence studies disclosed retention in the endoplasmic reticulum and defective cell-surface expression of a4R449H and defective Golgi trafficking of a2P405L Co-immunoprecipitation studies revealed an increase in association of a4R449H with the V0 assembly factor VMA21, and a reduced association with the V1 sector subunit, ATP6V1B1 (B1). For a4G820R, where stability, degradation, and trafficking were relatively unaffected, 3D molecular modeling suggested that the mutation causes dRTA by blocking the proton pathway. This study provides critical information that may assist rational drug design to manage dRTA and cutis laxa.

Band 3 nullVIENNA , a novel homozygous SLC4A1 p.Ser477X variant causing severe hemolytic anemia, dyserythropoiesis and complete distal renal tubular acidosis.

We describe the second patient with anionic exchanger 1/band 3 null phenotype (band 3 nullVIENNA ), which was caused by a novel nonsense mutation c.1430C>A (p.Ser477X) in exon 12 of SLC4A1. We also update on the previous band 3 nullCOIMBRA patient, thereby elucidating the physiological implications of total loss of AE1/band 3. Besides transfusion-dependent severe hemolytic anemia and complete distal renal tubular acidosis, dyserythropoiesis was identified in the band 3 nullVIENNA patient, suggesting a role for band 3 in erythropoiesis. Moreover, we also, for the first time, report that long-term survival is possible in band 3 null patients.

Band 3, the human red cell chloride/bicarbonate anion exchanger (AE1, SLC4A1), in a structural context.

The crystal structure of the dimeric membrane domain of human Band 3(1), the red cell chloride/bicarbonate anion exchanger 1 (AE1, SLC4A1), provides a structural context for over four decades of studies into this historic and important membrane glycoprotein. In this review, we highlight the key structural features responsible for anion binding and translocation and have integrated the following topological markers within the Band 3 structure: blood group antigens, N-glycosylation site, protease cleavage sites, inhibitor and chemical labeling sites, and the results of scanning cysteine and N-glycosylation mutagenesis. Locations of mutations linked to human disease, including those responsible for Southeast Asian ovalocytosis, hereditary stomatocytosis, hereditary spherocytosis, and distal renal tubular acidosis, provide molecular insights into their effect on Band 3 folding. Finally, molecular dynamics simulations of phosphatidylcholine self-assembled around Band 3 provide a view of this membrane protein within a lipid bilayer.

Decreased Renal Expression of H(+)-ATPase and Pendrin in a Patient with Distal Renal Tubular Acidosis Associated with Sjögren's Syndrome.

A 31-year-old woman with no significant past medical or family history was admitted with complaints of general weakness. Laboratory tests revealed: serum potassium 3.0 mEq/L, arterial blood pH 7.28, serum bicarbonate 17.8 mEq/L and urinary pH 7.0. Double-labeling confocal fluorescence microscopy using H(+)-ATPase and pendrin antibodies demonstrated a decreased expression of these proteins in the patient's renal collecting duct compared to normal controls. Anti-Sjögren's-syndrome-related antigen A (Anti-Ro/SS-A) and anti-Sjögren's syndrome type B (anti-La/SS-B) antibodies were strongly positive with very high titers, consistent with Sjögren's syndrome. We present a case of distal renal tubular acidosis-associated Sjögren's syndrome with a defect in H(+)-ATPase and pendrin in the renal collecting duct.

Mutations in exons 3 and 7 resulting in truncated expression of human ATP6V1B1 gene showing structural variations contributing to poor substrate binding-causative reason for distal renal tubular acidosis with sensorineural deafness.

Distal renal tubular acidosis (dRTA) is an autosomal recessive syndrome results defect in either proximal tubule bicarbonate reabsorption or in distal tubule H(+) secretion and is characterized by severe hyperchloraemic metabolic acidosis in childhood. dRTA is associated with functional variations in the ATP6V1B1 gene encoding ß1 subunit of H(+)-ATPase, key membrane transporters for net acid excretion of α-intercalated cells of medullary collecting ducts. In the present study, a 13-year-old male patient suffering with nephropathy and sensorineural deafness was reported in the Department of Nephrology. We predicted improper functioning of ATP6V1B1 gene could be the reason for diseased condition. Therefore, exons 3, 4, and 7 contributing active site of ATP6V1B1 gene was amplified and sequenced (Accession numbers: KF571726, KM222653). The obtained sequences were BLAST searched against the wild type ATP6V1B1 gene which showed novel mutations c.307 A > G, c.308 C > A, c.310 C > G, c.704 T > C, c.705 G > T, c.709 A > G, c.710 A > G, c.714 G > A, c.716 C > A, c.717delC, c.722 C > G, c.728insG, c.741insT, c.753G > C. These mutations resulted in the expression of truncated protein terminating at Lys 209. The mutated ATP6V1B1structure superimposed with wild type showed extensive variations with RMSD 1.336 Å and could not bind to substrate ADP leading to non-functional ATPase. These results conclusively explain these mutations in ATP6V1B1 gene resulted in structural changes causing accumulation of H(+) ions contributing to dRTA with sensorineural deafness.

Calcium citrate improves the epithelial-to-mesenchymal transition induced by acidosis in proximal tubular cells / Citrato de cálcio melhora a transição epitélio-mesenquimal induzida por acidose em células do túbulo proximal

INTRODUCTION: Epithelial-to-mesenchymal transition (EMT) is a key event in renal fibrosis. The aims of the study were to evaluate acidosis induced EMT, transforming-growth-factor (TGF) β1 role and citrate effect on it. METHODS: HK2 cells (ATCC 2290) were cultured in DMEM/HAM F12 medium, pH 7.4. At 80% confluence, after 24 hr under serum free conditions, cells were distributed in three groups (24 hours): A) Control: pH 7.4, B) Acidosis: pH 7.0 and C) Calcium citrate (0.2 mmol/L) + pH 7.0. Change (Δ) of intracellular calcium concentration, basal and after Angiotensin II (10-6M) exposition, were measured to evaluate cellular performance. EMT was evaluated by the expression of α-smooth muscle actin (α-SMA) and E-cadherin by immunocytochemistry and/or Western blot. TGF-β1 secretion was determined by ELISA in cell supernatant. RESULTS: At pH 7.0 HK2 cells significantly reduced E-cadherin and increased α-SMA expression (EMT). Supernatant TGF-β1 levels were higher than in control group. Calcium citrate decreased acidosis induced EMT and improved cells performance, without reduction of TGF-β production. CONCLUSIONS: Acidosis induces EMT and secretion of TGF-β1 in tubular proximal cells in culture and citrate improves cellular performance and ameliorates acidosis induced EMT.

INTRODUÇÃO: A transição epitélio-mesenquimal (TEM) é um evento chave na fibrose renal. Os objetivos do estudo foram avaliar se o citrato seria capaz de reverter a TEM induzida por acidose, e qual seria o papel do fator de crescimento transformador (TGF) β1 neste evento. MÉTODOS: Células de túbulo proximal (HK2) foram cultivadas em meio DMEM-F12, pH 7,4. Após confluência, as células foram distribuídas em três grupos A) controle: pH 7,4, B) Acidose: pH 7,0 e C) Acidose: pH 7,0 + citrato de cálcio (0,2 mmol/L). A variação na concentração de cálcio intracelular, antes e após a adição de angiotensina II (10-6M) foi medida para avaliar o desempenho celular. TEM foi avaliada pela expressão de α-actina de músculo liso (α-SMA) e E-caderina por imunocitoquímica e/ou de Western blot. A secreção de TGF-β1 foi determinada por ELISA no sobrenadante. RESULTADOS: Em pH 7,0, houve redução significante na expressão de E-caderina e aumento de α-SMA indicando a presença de TEM e a concentração de TGF-β1 foi maior do que no grupo controle. O citrato de cálcio melhorou TEM induzida pela acidose e a resposta das células à angiotensina II, sem redução do TGF-β. CONCLUSÕES: Acidose induz TEM e secreção de TGF-β1 em células tubulares proximais em cultura e o citrato melhora o desempenho celular e a TEM induzida por acidose.

Diagnóstico de anomalías dentarias en pacientes pediátricos con acidosis tubular distal mediante radiografía panorámica / Diagnóstico de anomalias dentárias em pacientes pediátricos com acidose tubular distal por meio de radiografia panorâmica

Objetivo: Determinar a presença de anomalias dentaria em crianças com acidose tubular distal. Métodos: Estudo transversal, sendo a amostra composta por 50 radiografias panorâmicas de crianças com idades entre 4 e 13 anos (29 meninos e 21 meninas) com diagnóstico de acidose tubular distal atendidas no Serviço de Nefrologia Pediátrica do Hospital "Dr. Enrique Tejera" de Valencia, Estado Carabobo, Venezuela. Adotou-se como critérios de exclusão: presença de síndromes dimórficas, alterações endócrinas, displasias ósseas, cromossomopatias e antecedentes traumáticos nos maxilares. As radiografias foram analisadas por um radiologista e um odontopediatra calibrados. Foram identificadas as anomalias de tamanho, número, forma e posição, sendo determinados quais dentes foram os mais afetados, sua localização e distribuição por gênero. As informações foram registradas em ficha específica e os dados analisados com o software SPSS versão 17, por meio da estatística descritiva (distribuições absolutas e percentuais). Resultados: A ocorrência de anomalias foi de 62%, sendo mais prevalentes a giroversão (40%), o taurodontismo (8%) e a microdontia (6%). Não se verificou diferença entre o sexo e o tipo de anomalia. Conclusão: Neste grupo de pacientes infantis com acidose tubular distal as anomalias dentárias mais frequentes foram a giroversão e o taurodontismo, sendo a prevalência observada semelhante a encontrada em pacientes sem alterações sistêmicas.

Objetivo: Determinar la presencia de anomalías dentarias en un grupo de niños con acidosis tubular distal. Métodos: Estudio transversal, la muestra, probabilísta intencional, consta de 50 radiografías panorámicas en niños entre 4 y 13 años de edad, (29 niños y 21 niñas) con diagnóstico de acidosis tubular distal tratados en el Hospital de Servicio de Nefrología Pediátrica "Dr. Enrique Tejera" en Valencia, estado Carabobo, Venezuela. Adoptado como criterios de exclusión: presencia de síndromes dimórfico, alteraciones endocrinas, displasias óseas, cromosómicas y antecedentes traumáticos en la mandíbula. Las radiografías fueron analizadas por un radiólogo y un dentista pediátrico calibrado. Se han identificado deficiencias en el tamaño, número, forma y posición e cuales dientes fueron afectados, su localización y distribución por edad y géneroy. La información fueron registrada en los archivos específicos e os datos fueron analizados con el programa SPSS versión 17, por medio de estadística descriptiva (distribuciones absolutas y porcentuales). Resultados: La ocurrencia de anomalías fue del 62%, y más giroversion prevalente (40%), el taurodontismo (8%) y microdoncia (6%). No hubo diferencia entre el sexo y el tipo de anomalía. Conclusión: En este grupo de pacientes pediátricos con acidosis tubular distal, las anomalías dentales más comunes fueron giroversion y taurodontismo, la prevalencia se observó similar a la encontrada en los pacientes sin cambios sistémicos.

Hypokalemic periodic paralysis due to proximal renal tubular acidosis in a case with membranoproliferative glomerulonephritis.

Proximal renal tubular acidosis (pRTA) is a rare disorder. Hypokalemia may be associated with it; occasionally leading to features like hypokalemic periodic paralysis. Though pRTA is a tubulointerstitial kidney disease, glomerulonephritis may occasionally lead to pRTA by tubular damage through leaking proteins, cytokines or by inflammatory infiltrates. In our reported case a 27 year old male had recurrent episodes of hypokalemic quadriparesis. Investigations revealed features of pRTA including hypokalemia and non-anion-gap hyperchloremic metabolic acidosis. His urine pH dropped to 5 with NH4Cl loading test. Kidney biopsy showed membranoproliferative glomerulonephritis with tubulointerstitial damage. Hypokalemic periodic paralysis and pRTA are uncommon associations of membranoproliferative glomerulonephritis.

Tubulointerstitial nephritis and renal tubular acidosis of different types are rare but important complications of primary biliary cirrhosis.

BACKGROUND: A very few cases of biopsy-proven tubulointerstitial nephritis (TIN) in patients with primary biliary cirrhosis (PBC) have been reported. Although the clinical importance of this association has been suggested, information on its clinicopathological features and prognosis is limited. METHODS: We reviewed 5955 renal biopsies processed at our department, and identified four patients with TIN associated with asymptomatic PBC. We evaluated clinicopathological features and outcomes in these patients, and reviewed the previously reported cases of TIN associated with PBC. RESULTS: Our four patients were female. The patients' age at the time of renal biopsy ranged from 36 to 77. Three patients had been treated with ursodeoxycholic acid. All patients had urinary abnormalities such as proteinuria and elevated levels of urinary ß(2)-microglobulin, and three patients had renal insufficiency. All patients had distal renal tubular acidosis (RTA), and two patients also had Fanconi syndrome. Renal biopsy showed severe lymphocyte infiltration in the tubules and interstitium with mild-to-moderate tubular atrophy and fibrosis. All patients responded well to steroid therapy. On review of the previously reported five cases, all patients were female. The patients' age ranged from 42 to 68. Apparent symptoms linked to PBC were not described. All patients had renal insufficiency. Three patients suffering from bone pains or bone fractures also had Fanconi syndrome. Marked or transient improvements were observed after steroid therapy in three patients. CONCLUSIONS: TIN and RTA of different types are extremely rare but one of the important extrahepatic complications of PBC. Steroid therapy can be beneficial in treating PBC patients with these renal complications.

Disfunción tubular renal distal en pacientes pediátricos con diagnóstico de desnutrición grave / Dystal renal tubular dysfunction in seriously undernourished pediatric patients

La acidosis metabólica es mas frecuente en los pacientes desnutridos graves que en los eutróficos. El objetivo del presente estudio fue evaluar la función tubular renal en 30 niños desnutridos graves hospitalizados. La investigación fue de tipo prospectiva, descriptiva de corte transversal, se realizó prueba de sobrecarga con bicarbonato de sodio al 5 por ciento a 30 desnutridos graves: marasmo, kwashiorkor o mixtos, con edades de 6 meses a 5 años, etiología primaria, de ambos sexos, hemodinámicamente estables, con acidosis metabólica, hipercloremia y anión gap urinario positivo. Se determinó la relación calcio/creatinina e índice ácido úrico/creatinina. Se calcularon las frecuencias absolutas, relativas, valores medios y desviación estándar. Los lactantes representaron 80 por ciento de los pacientes. Prevalecieron las formas clínicas kwashiorkor y mixtas de evolución crónica. En 12 (40,0 por ciento) pacientes se observó acidosis tubular renal distal. El valor promedio de la relación calcio/creatinina en menores de 2 años de edad fue de 0,362 ± 0,414 y en los mayores de 2 años de 0,265 ± 0,22. El valor promedio del índice ácido úrico/creatinina fue de 0,57 ± 0,28. La acidosis metabólica presente en los pacientes, de acuerdo a los resultados observados, obedece a una disfunción tubular renal distal. La interpretación de la relación calcio/creatinina e índice ácido úrico/creatinina urinaria resulta difícil, haciéndose necesario aumentar las investigaciones en estos pacientes.

Seriously undernourished patients have a bigger tendency to metabolic acidosis than euthrophic individuals. The objective of the present work was to realize a study of the renal tubular function in 30 severely undernourished children. The investigation was a prospective, descriptive and transversal study. A test of overload with 5 percent sodium bicarbonate was realized to 30 seriously undernourished children whose primari etiology was marasmus, kwashiorkor or with mixed conditions, with ages of 6 months to 5 years, from both sexes, hemodynamically stable, with metabolic acidosis, hiperchloremia and positive urinary anion gap. The relation calcium/creatinine and the index uric acid/creatinine were determined. The absolute and relatives frequencies, average values and standard deviations were calculated. Infants represented 80 percent of the evaluated patients. The clinical forms kwashiorkor and mixed forms, of chronic evolution prevailed. Distal tubular renal acidosis was observed in 12 patients (40 percent) after the test overload with 5 percent bicarbonate. The average values of the relation calcium/creatinine of children < 2 years was 0.362 ± 0.414 and of children > 2 years was 0.265 ± 0.222. The uric acid/creatinine index was 0.57 ± 0.28. Metabolic acidosis is frequent in serious infantile undernourishment, which, according to the results observed, obeys to distal renal tubular dysfunction. The interpretation of the relation calcium/creatinine and the uric acid/creatinine index is difficult, becoming necessary to increase the investigations in these patients.

Medullary sponge kidney associated with primary distal renal tubular acidosis and mutations of the H+-ATPase genes.

BACKGROUND: Medullary sponge kidney (MSK) is a rare congenital disease characterized by diffuse ectasia or dilation of precalyceal collecting tubules. Although its pathogenesis is unknown, the association with various congenital diseases suggests that it could be a developmental disorder. In addition to the typical clinical features of nephrocalcinosis and urolithiasis, patients with MSK show tubular function defects of acidification and concentration. These are considered to be secondary to morphological changes of collecting tubules. Primary distal renal tubular acidosis (dRTA) is a rare genetic disease caused by mutations in different genes involved in the secretion of H(+) ions in the intercalated cells of the collecting duct required for final excretion of fixed acids. Both autosomal dominant and autosomal recessive forms have been described, the latter is also associated with sensorineural hearing loss. METHODS AND RESULTS: We report two patients presenting with dRTA, late sensorineural hearing loss and MSK, in whom molecular investigations demonstrated the presence of mutations of the H(+) proton pump ATP6V1B1 and ATP6V0A4 genes. CONCLUSIONS: These observations, including a previous description of a similar case in the literature, indicate that MSK could be a consequence of the proton pump defect, thus can potentially provide new insights into the pathogenesis of MSK.

Tratamiento a largo plazo con citrato de potasio en pacientes nefrolitiásicos adultos con hipocitraturia o diátesis gotosa / Long-Term treatment of adult nephrolithiasis patients with hypocitraturia or gouty diathesis with potassium citrate

Pocos estudios han evaluado el tratamiento a largo plazo con citrato de potasio en pacientes con nefrolitiasis por oxalato de calcio o ácido úrico cuyos factores de riesgo metabólico urinario son hipocitraturia o diátesis gotosa. Nosotros evaluamos retrospectivamente las historias clínicas de 92 pacientes adultos con litiasis renal recurrente cuyos factores de riesgo metabólico eran hipocitraturia aislada o diátesis gotosa que fueron tratados con citrato de potasio 30 a 60 meq/día, una a dos veces por día, por más de 3 meses.... Concluimos que el tratamiento con citrato de potasio efectivamente corrige los trastornos metabólicos en pacientes con hipocitraturia y diátesis gotosa con una disminución asociada en el calcio urinario y que estos efectos son sostenidos en el tiempo.

Few studies have evaluated the long term treatmente with potassium citrate in patients with calcium oxalate o uric acid nephrolithiasis whose urine metabolic risk factores were hypocitraturia or gouty diathesis. We retrospectively reviewed the charts of 92 adult patients with recurrent renal stones whose urine metabolic risk factores were either hypocitraturia or gouty diathesis who were treated with potassium citrate 30 at 60 meq/d one or two times daily, for more than 3 months... We conclude that potassium citrate effectively corrects metabolic derangements in patients with hypocitraturia and couty diathesis with an associated decrease in urinary calcium and these effects were sustained in time.

2007 Homer W. Smith award: control of terminal differentiation in epithelia.

The intercalated cell of the cortical collecting tubule exists in two functional and morphologic forms: alpha cells secrete acid, while beta cells secrete HCO(3). It was found that beta cells convert to alpha type when the animal ingests an acid diet or when isolated perfused tubules are exposed to acid. This conversion of cell phenotype requires the induction of new genes, accompanied by a change in cell shape, development of microvilli, and apical endocytosis. All of these changes are reminiscent of terminal differentiation in epithelial cells. Using a beta intercalated cell line, the cause of this phenotypic change was identified as a new extracellular matrix protein, which was termed hensin. When the action of hensin is blocked, the conversion of beta to alpha intercalated cells is prevented and the animals develop distal renal tubular acidosis. Hensin is expressed in most epithelia, and global knockout of hensin results in embryonic lethality at the time of development of the first columnar epithelium, the visceral endoderm. Furthermore, hensin also seems to be involved in the differentiation of transitional and perhaps stratified epithelia as well. A large number of human carcinomas have deletions in the human ortholog of hensin (DMBT1). Collectively, these studies demonstrate that hensin is a mediator of terminal differentiation in many epithelia.