Severe perinatal liver disease and Down syndrome: an apparent relationship

The hematopoietic microenvironment of the fetal liver and transient abnormal myelopoiesis associated with Down syndrome: A review

Transient abnormal myelopoiesis (TAM) in neonates with Down syndrome is a distinct form of leukemia or preleukemia that mirrors the hematological features of acute megakaryoblastic leukemia. However, it typically resolves spontaneously in the early stages. TAM originates from fetal liver (FL) hematopoietic precursor cells and emerges due to somatic mutations in GATA1 in utero. In TAM, progenitor cells proliferate and differentiate into mature megakaryocytes and granulocytes. This process occurs both in vitro, aided by hematopoietic growth factors (HGFs) produced in the FL, and in vivo, particularly in specific anatomical sites like the FL and blood vessels. The FL's hematopoietic microenvironment plays a crucial role in TAM's pathogenesis and may contribute to its spontaneous regression. This review presents an overview of current knowledge regarding the unique features of TAM in relation to the FL hematopoietic microenvironment, focusing on the functions of HGFs and the pathological features of TAM.

Aging exacerbates oxidative stress and liver fibrosis in an animal model of Down Syndrome

Down Syndrome (DS) is a common genetic disorder characterized by an extra copy of chromosome 21, leading to dysregulation of various metabolic pathways. Oxidative stress in DS is associated with neurodevelopmental defects, neuronal dysfunction, and a dementia onset resembling Alzheimer's disease. Additionally, chronic oxidative stress contributes to cardiovascular diseases and certain cancers prevalent in DS individuals. This study investigates the impact of ageing on oxidative stress and liver fibrosis using a DS murine model (Ts2Cje mice). Our results show that DS mice show increased liver oxidative stress and impaired antioxidant defenses, as evidenced by reduced glutathione levels and increased lipid peroxidation. Therefore, DS liver exhibits an altered inflammatory response and mitochondrial fitness as we showed by assaying the expression of HMOX1, CLPP, and the heat shock proteins Hsp90 and Hsp60. DS liver also displays dysregulated lipid metabolism, indicated by altered expression of PPARα, PPARγ, FATP5, and CTP2. Consistently, these changes might contribute to non-alcoholic fatty liver disease development, a condition characterized by liver fat accumulation. Consistently, histological analysis of DS liver reveals increased fibrosis and steatosis, as showed by Col1a1 increased expression, indicative of potential progression to liver cirrhosis. Therefore, our findings suggest an increased risk of liver pathologies in DS individuals, particularly when combined with the higher prevalence of obesity and metabolic dysfunctions in DS patients. These results shed a light on the liver's role in DS-associated pathologies and suggest potential therapeutic strategies targeting oxidative stress and lipid metabolism to prevent or mitigate liver-related complications in DS individuals.

Novel insights from fetal and placental phenotyping in 3 mouse models of Down syndrome

BACKGROUND

In human fetuses with Down syndrome, placental pathology, structural anomalies and growth restriction are present. There is currently a significant lack of information regarding the early life span in mouse models of Down syndrome.

OBJECTIVE

The objective of this study was to examine embryonic day 18.5 and placental phenotype in the 3 most common mouse models of Down syndrome (Ts65Dn, Dp(16)1/Yey, Ts1Cje). Based on prenatal and placental phenotyping in 3 mouse models of Down syndrome, we hypothesized that one or more of them would have a similar phenotype to human fetuses with trisomy 21, which would make it the most suitable for in utero treatment studies.

STUDY DESIGN

Here, C57BL6J/6 female mice were mated to Dp(16)1/Yey and Ts1Cje male mice and Ts65Dn female mice to C57BL/B6Eic3Sn.BLiAF1/J male mice. At embryonic day 18.5, dams were euthanized. Embryos and placentas were examined blindly for weight and size. Embryos were characterized as euploid or trisomic, male or female by polymerase chain reaction. A subset of embryos (34 euploid and 34 trisomic) were examined for malformations.

RESULTS

The Ts65Dn mouse model showed the largest differences in fetal growth, brain development, and placental development when comparing euploid and trisomic embryos. For the Dp(16)1/Yey mouse model, genotype did not impact fetal growth, but there were differences in brain and placental development. For the Ts1Cje mouse model, no significant association was found between genotype and fetal growth, brain development, or placental development. Euploid mouse embryos had no congenital anomalies; however, 1 mouse embryo died. Hepatic necrosis was seen in 6 of 12 Dp(16)1/Yey (50%) and 1 of 12 Ts1Cje (8%) mouse embryos; hepatic congestion or inflammation was observed in 3 of 10 Ts65Dn mouse embryos (30%). Renal pelvis dilation was seen in 5 of 12 Dp(16)1/Yey (42%), 5 of 10 Ts65Dn (50%), and 3 of 12 Ts1Cje (25%) mouse embryos. In addition, 1 Ts65Dn mouse embryo and 1 Dp(16)1/Yey mouse embryo had an aortic outflow abnormality. Furthermore, 2 Ts1Cje mouse embryos had ventricular septal defects. Ts65Dn mouse placentas had increased spongiotrophoblast necrosis.

CONCLUSION

Fetal and placental growth showed varying trends across strains. Congenital anomalies were primarily seen in trisomic embryos. The presence of liver abnormalities in all 3 mouse models of Down syndrome (10 of 34 cases) is a novel finding. Renal pelvis dilation was also common (13 of 34 cases). Future research will examine human autopsy material to determine if these findings are relevant to infants with Down syndrome. Differences in placental histology were also observed among strains.

Clinical features of 35 Down syndrome patients with transient abnormal myelopoiesis at a single institution

Transient abnormal myelopoiesis (TAM) is a unique clonal myeloproliferation characterized by immature megakaryoblasts that occurs in 5-10% of neonates with Down syndrome (DS). Although TAM regresses spontaneously in most patients, approximately 20% of TAM cases result in early death, and approximately 20% of survivors develop acute megakaryoblastic leukemia (AMKL). We retrospectively reviewed records of 35 DS patients with TAM to determine the correlation between clinical characteristics and blast percentage. Thirteen of the 35 patients were classified as low blast percentage TAM (LBP-TAM), defined as TAM with a peak peripheral blast percentage ≤ 10%. Although no patient with LBP-TAM experienced systemic edema, disseminated intravascular coagulation, or early death, eight patients had elevated direct bilirubin levels (> 2 mg/dl) and one developed AMKL. All patients with LBP-TAM had serum markers of liver fibrosis that exceeded the normal limits, and two patients underwent liver biopsy to clarify the etiology of pathological jaundice. Taken together, our results suggest that patients with LBP-TAM may be at risk of liver fibrosis and liver failure, similarly to patients with classical TAM. Although these patients generally have a good prognosis, they should be carefully monitored for potential development of liver disease and leukemia.

Efficacy of Intravenous Immunoglobulin/Exchange Transfusion Therapy on Gestational Alloimmune Liver Disease

Background: Gestational alloimmune liver disease (GALD) is a rare but critical cause of neonatal liver failure. After discovering the maternal-fetal alloimmune mechanism, intravenous immunoglobulin (IVIG) with or without exchange transfusion (ET) has gradually replaced antioxidant cocktails as the first-line therapy. Whether such therapy changes the outcome of neonates with GALD is yet to be defined. Method: We reported a pair of twins with discordant presentations, mild and self-limited in the older, whereas liver failure in the younger, who was successfully rescued by ET and IVIG. To investigate the outcome after therapeutic alteration, 39 cases between 2005 and 2020 from literature research were collected. Results: Half of the collected cases (47.1%) were preterm. Common presentations were ascites, jaundice, respiratory distress, hepatomegaly, and edema. Leading laboratory abnormalities were coagulopathy, hypoalbuminemia, and elevated serum ferritin. Salivary gland biopsy and magnetic resonance imaging detected extrahepatic siderosis in 70% (14/20) and 56% (14/25), respectively. IVIG, ET, and liver transplantation were performed in 19 (48.7%), 15 (38.5%), and 8 (20.5%) patients, respectively. The overall survival (OS) rate and native liver survival (NLS) rate were 64.1% (25/39) and 43.6% (17/39), respectively. Although the compiled results did not support a significant benefit, the OS and NLS were higher in the IVIG with/without ET group compared with those treated with conventional therapy [OS (70 vs. 57.9%) and NLS (55 vs. 31.6%), respectively]. Conclusion: A high index of suspicion for GALD is crucial when facing a neonate with liver failure. Despite no significant influence on the outcome over conventional therapy in such a rare and detrimental disease, IVIG with or without ET can be worth trying before resorting to liver transplantation, which is resource-demanding and technique-challenging in small infants.

Neonatal hemochromatosis in a newborn with Down syndrome

Background: Neonatal hemochromatosis (NH) is a cause of neonatal/pediatric acute liver failure. Liver dysfunction/failure in Down syndrome had been described in relation to increased susceptibility to infection and transient myeloproliferative disease (TMD). The occurrence of NH in Down syndrome is described in only a few case reports. Material and methods: A complete autopsy have been performed in a 79-day-old infant with severe liver dysfunction. TMD was suspected antemortem following a report of peripheral blood leukocytosis with 14% atypical cells. Results: The complete autopsy revealed NH-phenotype to be the cause of liver dysfunction and subsequent death. Conclusion: Though TMD is a common cause of liver dysfunction in Down syndrome, NH should also be considered in its differential.

Chemokine levels predict progressive liver disease in Down syndrome patients with transient abnormal myelopoiesis

BACKGROUND

Transient abnormal myelopoiesis (TAM) is a neonatal preleukemic syndrome that occurs exclusively in neonates with Down syndrome (DS). Most affected infants spontaneously resolve, although some patients culminate in hepatic failure despite the hematological remission. It is impossible to determine the patients who are at high risk of progressive liver disease and leukemic transformation. The objective is to search for biomarkers predicting the development of hepatic failure in DS infants with TAM.

METHODS

Among 60 newborn infants with DS consecutively admitted to our institutions from 2003 to 2016, 41 infants with or without TAM were enrolled for the study. Twenty-two TAM-patients were classified into "progression group" (n = 7) that required any therapy and "spontaneous resolution group" (n = 15). Serum concentrations of chemokines (CXCL8, CXCL9, CXCL10, CCL2 and CCL5) and transforming growth factor (TGF)-β1 were measured at diagnosis of TAM for assessing the outcome of progressive disease.

RESULTS

Three patients developed leukemia during the study period (median, 1147 days; range, 33-3753). Three died of hepatic failure. All patients in the progression group were preterm birth <37 weeks of gestational age and were earlier than those in the spontaneous resolution group (median, 34.7 vs. 37.0 weeks, p < 0.01). The leukocyte counts and CXCL8 and CCL2 levels at diagnosis in the progression group were higher than those in the spontaneous resolution group (leukocyte: median, 81.60 vs. 27.30 × 10⁹/L, p = 0.01; CXCL8: 173.8 vs. 34.3 pg/ml, p < 0.01; CCL2: 790.3 vs. 209.8 pg/mL, p < 0.01). Multivariate analyses indicated that an increased CCL2 value was independently associated with the progression and CXCL8 with the death of liver failure, respectively (CCL2: standardized coefficient [sc], 0.43, p < 0.01; CXCL8: sc = -0.46, p = 0.02).

CONCLUSION

High levels of circulating CXCL8 and CCL2 at diagnosis of TAM may predict progressive hepatic failure in DS infants.

Role of monocyte chemoattractant protein-1 in liver fibrosis with transient myeloproliferative disorder in down syndrome

Liver fibrosis is a common complication associated with transient myeloproliferative disorder (TMD) in Down syndrome (DS). The exact molecular pathogenesis that regulates disease progression is largely unknown. We recently found serum and/or urinary monocyte chemoattractant protein‐1 (MCP‐1) as a novel biomarker of liver fibrosis. This study was an in vitro analysis to investigate the fibrogenic activity of MCP‐1 using the collagen‐producing LX‐2 human hepatic stellate cell line. We also examined the fibrogenic activity of serum from a male neonate with DS in whom late‐onset liver fibrosis developed even after the resolution of TMD. MCP‐1 stimulated both cell growth and collagen synthesis of LX‐2 in a dose‐dependent manner. Patient serum obtained during the active disease phase significantly up‐regulated fibrogenic activity, which was suppressed in the presence of MCP‐1‐blocking antibody. Transient transforming growth factor beta 1 stimulation primed LX‐2 to induce prolonged hypersecretion of MCP‐1 in the culture supernatant and in collagen synthesis, which was suppressed with MCP‐1 blocking antibody as well. Conclusion: MCP‐1 accounts for the prolonged activation of collagen‐producing hepatic stellate cells in both a paracrine and autocrine manner, thereby promoting liver fibrosis. Anti‐cytokine therapy targeting the fibrogenic cytokines of MCP‐1, for example, herbal medicine, could provide a new therapeutic intervention for liver fibrosis associated with TMD in DS. (Hepatology Communications 2018;2:230‐236)

Shotgun metabolomic profiles in maternal urine identify potential mass spectral markers of abnormal fetal biochemistry - dihydrouracil and progesterone in the metabolism of Down syndrome

In Down syndrome (DS) in particular, the precise cellular mechanisms linking genotype to phenotype is not straightforward despite a clear mapping of the genetic cause. Metabolomic profiling might be more revealing in understanding molecular-cellular mechanisms of inborn errors of metabolism/syndromes than genomics alone and also result in new prenatal screening approaches. The urinary metabolome of 122 maternal urine from women with and without an aneuploid pregnancy (predominantly Down syndrome) were compared by both zwitterionic hydrophilic interaction chromatography (ZIC-HILIC) and reversed-phase liquid chromatography (RPLC) coupled to hybrid ion trap time of flight mass spectral analysis. ZIC-HILIC mass spectrometry resolved 10-fold more unique molecular ions than RPLC mass spectrometry, of which molecules corresponding to ions of m/z 114.07 and m/z 314.20 showed maternal urinary level changes that significantly coincided with the presence of a DS fetus. The ion of m/z 314.20 was identified as progesterone and m/z 114.07 as dihydrouracil. A metabolomics profiling-based maternal urinary screening test modelled from this separation data would detect approximately 87 and 60.87% (using HILIC-MS and RPLC-MS, respectively) of all DS pregnancies between 9 and 23 weeks of gestation with no false positives.

Fetal liver stromal cells support blast growth in transient abnormal myelopoiesis in Down syndrome through GM-CSF

Transient abnormal myelopoiesis (TAM) in neonates with Down syndrome, which spontaneously resolves within several weeks or months after birth, may represent a very special form of leukemia arising in the fetal liver (FL). To explore the role of the fetal hematopoietic microenvironment in the pathogenesis of TAM, we examined the in vitro influences of stromal cells of human FL and fetal bone marrow (FBM) on the growth of TAM blasts. Both FL and FBM stromal cells expressed mesenchymal cell antigens (vimentin, α-smooth muscle actin, CD146, and nestin), being consistent with perivascular cells/mesenchymal stem cells that support hematopoietic stem cells. In addition, a small fraction of the FL stromal cells expressed an epithelial marker, cytokeratin 8, indicating that they could be cells in epithelial-mesenchymal transition (EMT). In the coculture system, stromal cells of the FL, but not FBM, potently supported the growth of TAM blast progenitors, mainly through humoral factors. High concentrations of hematopoietic growth factors were detected in culture supernatants of the FL stromal cells and a neutralizing antibody against granulocyte-macrophage colony-stimulating factor (GM-CSF) almost completely inhibited the growth-supportive activity of the culture supernatants. These results indicate that FL stromal cells with unique characteristics of EMT cells provide a pivotal hematopoietic microenvironment for TAM blasts and that GM-CSF produced by FL stromal cells may play an important role in the pathogenesis of TAM.

De novo duplication of chromosome 16p in a female infant with signs of neonatal hemochromatosis

Reported cases of "pure" duplication of the entire short arm of chromosome 16 (16p) are rare, with only 7 patients described in the literature. We report on a female infant with de novo 16p duplication localized to the short arm of chromosome 6, detected by chromosomal analysis and characterized by array CGH and fluorescence in situ hybridization. This baby girl presented with clinical symptoms characteristic of patients with duplications of the short arm of chromosome 16: psychomotor retardation, constitutional growth delay and specific dysmorphic features, including proximally placed hypoplastic thumbs. In addition, she exhibited evidence of neonatal hemochromatosis as shown by direct hyperbilirubinemia, iron overload and elevated liver enzyme levels. To our knowledge, this is the first report of signs of neonatal hemochromatosis in a patient with 16p duplication.

Neonatal hemochromatosis

Neonatal hemochromatosis is a clinical condition in which severe liver disease in the newborn is accompanied by extrahepatic siderosis. Gestational alloimmune liver disease (GALD) has been established as the cause of fetal liver injury resulting in nearly all cases of NH. In GALD, a women is exposed to a fetal antigen that she does not recognize as "self" and subsequently begins to produce IgG antibodies that are directed against fetal hepatocytes. These antibodies bind to fetal liver antigen and activate the terminal complement cascade resulting in hepatocyte injury and death. GALD can cause congenital cirrhosis or acute liver failure with and without iron overload and siderosis. Practitioners should consider GALD in cases of fetal demise, stillbirth, and neonatal acute liver failure. Identification of infants with GALD is important as treatment is available and effective for subsequent pregnancies.

French retrospective multicentric study of neonatal hemochromatosis: importance of autopsy and autoimmune maternal manifestations

Neonatal hemochromatosis is a rare disease that causes fetal loss and neonatal death in the 1st weeks of life and is one of the most common causes of liver failure in the neonate. The diagnosis is mostly made retrospectively, based on histopathologic features of severe liver fibrosis associated with hepatic and extrahepatic siderosis. Several etiologies may underlie this phenotype, including a recently hypothesized gestational alloimmune disease. Fifty-one cases of liver failure with intrahepatic siderosis in fetuses and neonates were analyzed retrospectively. Maternal and infant data were collected from hospitalization and autopsy reports. All available slides were reviewed independently by 3 pathologists. Immunologic studies were performed on maternal sera collected immediately after delivery. The diagnosis of neonatal haemochromatosis was retained in 33 cases, including 1 case with Down syndrome and 1 case with myofibromas. Liver siderosis was inversely proportional to fibrosis progression. In fetuses, iron storage was more frequent in the thyroid than in the pancreas. Perls staining in labial salivary glands was positive in 1 of 5 cases. Abnormal low signal intensity by magnetic resonance imaging was detected in the pancreas in 2 of 7 cases. Renal tubular dysgenesis was observed in 7 of 23 autopsy cases. Chronic villitis was seen in 7 of 15 placentas. Half of the mothers presented with an autoimmune background and/or autoantibodies in their sera. Our work highlights the importance of autopsy in cases of neonatal hemochromatosis and marshals additional data in support of the hypothesis that neonatal hemochromatosis could reflect maternal immune system dysregulation.

Multipotent stem/progenitor cells in the human foetal biliary tree

BACKGROUND & AIMS

Biliary tree, liver, and pancreas share a common embryological origin. We previously demonstrated the presence of stem/progenitor cells of endodermal origin in the adult human extrahepatic biliary tree. This study evaluated the human foetal biliary trees as sources of stem/progenitor cells of multiple endodermal-derived mature fates.

METHODS

Human foetal intrahepatic and extrahepatic biliary tree tissues and isolated cells were tested for cytoplasmic and surface markers of stem cells and committed progenitors, as well as endodermal transcription factors requisite for a liver versus pancreatic fate. In vitro and in vivo experiments were conducted to evaluate the potential mature fates of differentiation.

RESULTS

Foetal biliary tree cells proliferated clonogenically for more than 1 month on plastic in a serum-free Kubota medium. After culture expansion, cells exhibited multipotency and could be restricted to certain lineages under defined microenvironments, including hepatocytes, cholangiocytes, and pancreatic islet cells. Transplantation of foetal biliary tree cells into the livers of immunodeficient mice resulted in effective engraftment and differentiation into mature hepatocytes and cholangiocytes.

CONCLUSIONS

Foetal biliary trees contain multipotent stem/progenitor cells comparable with those in adults. These cells can be easily expanded and induced in vitro to differentiate into liver and pancreatic mature fates, and engrafted and differentiated into mature cells when transplanted in vivo. These findings further characterise the development of these stem/progenitor cell populations from foetuses to adults, which are thought to contribute to liver and pancreas organogenesis throughout life.

Early-occurring proliferation defects in peripheral tissues of the Ts65Dn mouse model of Down syndrome are associated with patched1 over expression

Down syndrome (DS) is a genetic pathology due to the triplication of human chromosome 21. In addition to mental retardation, individuals with DS exhibit a large range of variable traits, including co-occurring congenital malformations. It is now clear that neurogenesis impairment underlies the typically reduced brain size and, hence, mental retardation in individuals with DS. The small body size and the constellation of congenital malformations in children with DS suggest that proliferation defects may involve peripheral tissues, in addition to the brain. The goal of the current study was to establish whether a generalized impairment of cell proliferation is a key feature of the trisomic condition. We used the Ts65Dn mouse, a widely used DS model, and examined proliferation in tissues with different embryological origin by 5-bromo-2-deoxyuridine immunohistochemistry. We found that 2-day-old (P2) Ts65Dn mice had notably fewer proliferating cells in the heart and liver, and in all proliferating niches of the skin and intestine. A reduced proliferation rate was still present in the intestine at P15. In all tissues, Ts65Dn mice had a similar number of apoptotic cells as euploid mice, indicating no unbalance in cell death. In the skin, liver and intestine of trisomic mice, we found a higher expression of patched1 (Ptch1), a receptor that represses the mitogenic sonic hedgehog (Shh) pathway. This suggests that Ptch1-dependent inhibition of Shh signaling may underlie proliferation impairment in trisomic peripheral tissues. In agreement with the widespread reduction in proliferation, neonate trisomic mice had a reduced body weight and this defect was still present at 30 days of age. Our findings show that, in all examined peripheral tissues, Ts65Dn mice exhibit a notable reduction in proliferation rate, suggesting that proliferation impairment may be a generalized defect of trisomic precursor cells.

Population-based study of incidence and clinical outcome of neonatal cholestasis in patients with Down syndrome

OBJECTIVE

To study the incidence and outcome of Down syndrome-associated neonatal cholestasis in a population-based cohort.

STUDY DESIGN

This retrospective study included all neonates diagnosed with Down syndrome born between January 2005 and September 2011 in the County of Stockholm, Sweden. Clinical and biochemical data related to cholestasis, early gastrointestinal (GI) involvement, congenital heart defects (CHD), and bone marrow disease were obtained from the computer-based hospital chart system.

RESULTS

A total of 206 newborns with Down syndrome were identified, for an incidence of 1 in 880 newborns. Prevalences of other diseases in these newborns included 47% for CHD, 11.2% for GI involvement, 3.9% for neonatal cholestasis, and 3.4% for bone marrow disease. Neonatal cholestasis was more common in the newborns with GI involvement (3 of 23 vs 5 of 183 of those without GI involvement; P = .047), CHD (8 of 96 vs 0 of 110 of those without CHD; P = .0019), and bone marrow disease (3 of 7 vs 5 of 199 of those without bone marrow disease; P = .0013). Cholestasis was severe in 3 patients (all of whom had bone marrow disease, with liver failure and early death in 2), and transient in 5 patients.

CONCLUSION

Neonatal cholestasis occurs in a significant percentage of patients with Down syndrome and is always associated with involvement of other organs. The outcome is variable, being most severe in newborns with the combination of neonatal cholestasis and bone marrow disease.

Hepatic failure, neonatal hemochromatosis and porto-pulmonary hypertension in a newborn with trisomy 21--a case report

Liver failure in neonates is a rare but often fatal disease. Trisomy 21 is not usually associated with significant infantile liver disease. If present, hepatic dysfunction in an infant with Trisomy 21 is likely to be attributed to transient myeloproliferative disorder with hepatic infiltration by hematopoietic elements and may be associated with secondary hemosiderosis. A less commonly recognized cause of liver failure in neonates with Trisomy 21 is neonatal hemochromatosis (NH); this association has been reported in nine cases of Trisomy 21 in literature. NH is a rare, severe liver disease of intra-uterine onset that is characterized by neonatal liver failure and hepatic and extrahepatic iron accumulation that spares the reticuloendothelial system. NH is the most frequently recognized cause of liver failure in neonates and the commonest indication for neonatal liver transplantation. Although porto-pulmonary hypertension (PPH) has been reported as a complication of liver failure in adults and older children, this has not been reported in neonates with liver failure of any etiology. This is probably due to the rarity of liver failure in newborns, delayed diagnosis and high mortality. The importance of recognizing PPH is that it is reversible with liver transplantation but at the same time increases the risk of post-operative mortality. Therefore, early diagnosis of PPH is critical so that early intervention can improve the chances of successful liver transplantation. We report for the first time the association of liver failure with porto-pulmonary hypertension secondary to NH in an infant with Trisomy 21.

Serum thrombopoietin level and thrombocytopenia during the neonatal period in infants with Down's syndrome

BACKGROUND

The pathogenesis of thrombocytopenia during the neonatal period in Down's syndrome (DS) infants remains unclear.

OBJECTIVE

To elucidate kinetic changes of serum thrombopoietin (TPO) level and platelet count, and their correlation in DS neonates.

STUDY DESIGN

Twelve DS infants (male/female: 7/5, term/late preterm: 10/2) born between 1997 and 2007 were included. Blood samples were serially collected during the neonatal period and serum TPO levels were determined in 44 sera using an enzyme-linked immunosorbent assay.

RESULTS

Thrombocytopenia <150 x 10(9) per liter was observed in seven (58%) patients. In 12 DS patients, the median TPO value showed 2.86 fmol ml(-1) on day 0, rose to 4.64 fmol ml(-1) on day 2, and thereafter decreased to 4.30 fmol ml(-1) on day 5, 2.40 fmol ml(-1) on days 11-15, and 1.75 fmol ml(-1) on days 28-30. This kinetics parallels that in historical non-DS controls. In 35 pair sample analysis from 11 patients without transient myeloproliferative disease, TPO level inversely correlated with platelet count (r=-0.38, P=0.023). However, there was no significant difference in TPO concentrations between thrombocytopenic and non-thrombocytopenic DS individuals.

CONCLUSIONS

This is the first study to describe the relationship between TPO level and platelet count in neonates with DS. Median TPO levels and their kinetic changes in DS neonates are comparable to those in non-DS controls. In contrast to earlier findings in several studies showing higher TPO concentrations in thrombocytopenic non-DS newborns than those in non-thrombocytopenic counterparts, the response of the TPO system to thrombocytopenia in DS during the neonatal period seems suboptimal.

Osteopontin expression in the liver with severe perisinusoidal fibrosis: autopsy case of Down syndrome with transient myeloproliferative disorder

Down syndrome with transient myeloproliferative disorder (TMD) is often associated with perinatal liver fibrosis. The authors recently encountered an autopsy case of this disease with a characteristic severe perisinusoidal liver fibrosis. Osteopontin (OPN) is a molecule that plays an important role in diverse fibro-inflammatory diseases. The purpose of the present report was to examine the involvement of OPN in development of the Down syndrome-associated liver fibrosis. Histology indicated severe perisinusoidal fibrosis and ductular arrangements of hepatocytes in the liver. Appearance of atypical megakaryocytes in the liver, a feature of TMD associated with Down syndrome, was not evident. On immunohistochemistry expression of OPN was observed in hepatocytes often having ductular arrangements and infiltrating macrophages. In contrast, a small number of transforming growth factor-beta1 (TGF-beta1)-positive mononuclear cells were present in the liver. Numerous activated hepatic stellate cells (HSC) expressing alpha-smooth muscle actin (alpha-SMA) were seen in the perisinusoidal area. A recent report indicated that OPN could directly activate the HSC. Thus, it is suggested that OPN produced by hepatocytes and macrophages induces activation of the HSC, and leads to the development of perisinusoidal liver fibrosis.

Transient leukemia (transient myeloproliferative disorder, transient abnormal myelopoiesis) of Down syndrome

Transient leukemia of Down syndrome (DS-TL), also known as transient myeloproliferative disorder of Down syndrome (DS) and transient abnormal myelopoiesis of DS, occurs in approximately 10% of DS neonates and in phenotypically normal neonates with trisomy 21 mosaicism. In DS-TL, peripheral blood analysis shows variable numbers of blasts and, usually, thrombocytopenia; other cytopenias are uncommon. Bone marrow characteristics of DS-TL are, likewise, variable, though (in contrast to other leukemias) the bone marrow blast differential can be lower than the peripheral blood blast differential. The blasts of DS-TL typically show light microscopic, ultrastructural, and flow cytometric evidence of megakaryocyte differentiation. DS-TL neonates have a approximately 15% risk of developing potentially fatal liver disease and show <10% incidence of hydrops fetalis. Additional manifestations of DS-TL include cutaneous involvement, hyperviscosity, myelofibrosis, cardiopulmonary failure, splenomegaly, and spleen necrosis. Despite its typical transient nature, 20% to 30% of DS-TL patients develop overt (nontransient) acute leukemia, usually within 3 years and typically of the M7 phenotype (acute megakaryoblastic leukemia). The pathogenesis of DS-TL (and of subsequent acute leukemia) involves mutation of GATA1 (on chromosome X), which normally encodes a transcription factor integral to normal development of erythroid, megakaryocytic, and basophilic/mast cell lines. The pathogenetic role of trisomy 21 in DS-TL is unclear. Though indications for chemotherapy in DS-TL have not been firmly established, the blasts of DS-TL are sensitive to low-dose cytosine arabinoside.

A prospective study of the natural history of transient leukemia (TL) in neonates with Down syndrome (DS): Children's Oncology Group (COG) study POG-9481

A unique transient leukemia (TL) has been described in newborns with Down syndrome (DS; or trisomy 21 mosaics). This leukemia has a high incidence of spontaneous remission; however, early death and subsequent development of acute megakaryoblastic leukemia (AMKL) have been reported. We prospectively evaluated 48 infants with DS and TL to determine the natural history and biologic characteristics of this disease, identify the clinical characteristics associated with early death or subsequent leukemia, and assess the incidence of subsequent leukemia. Blast cells associated with TL in DS infants exhibited FAB M(7) morphology and phenotype. Most infants (74%) had trisomy 21 (or mosaicism) as the only cytogenetic abnormality in the blast cells. Most children were able to spontaneously clear peripheral blasts (89%), normalize blood counts (74%), and maintain a complete remission (64%). Early death occurred in 17% of infants and was significantly correlated with higher white blood cell count at diagnosis (P < .001), increased bilirubin and liver enzymes (P < .005), and a failure to normalize the blood count (P = .001). Recurrence of leukemia occurred in 19% of infants at a mean of 20 months. Development of leukemia was significantly correlated with karyotypic abnormalities in addition to trisomy 21 (P = .037). Ongoing collaborative clinical studies are needed to determine the optimal role of chemotherapy for infants at risk for increased mortality or disease recurrence and to further the knowledge of the unique biologic features of this TL.

Neonatal hemochromatosis: fetal liver disease leading to liver failure in the fetus and newborn

Acute liver failure in the newborn is relatively rare but often fatal. The broadest definition of acute liver failure is failure of the vital functions of the liver occurring within weeks or a few months of the onset of clinical liver disease. Therefore, by definition, any liver failure in the newborn can be construed to be acute liver failure. A second component of the general definition of acute liver failure is the lack of known preexisting liver disease. In the case of neonatal acute liver failure, preexisting disease would by definition be liver disease that affects the fetus. Almost nothing is known about fetal onset liver failure, and there is no literature addressing the subject. This review will address fetal liver disease that leads to liver failure in the fetus or newborn.

Transient leukemia in newborns with Down syndrome

Children with Down syndrome (DS) have a 10- to 20-fold increased risk of developing leukemia, particularly acute megakaryocytic leukemia. Newborns with DS or trisomy 21 mosaicism may exhibit a particularly unique form of leukemia that historically has been associated with a high rate of spontaneous remission. This transient leukemia (TL) has been shown to be a clonal proliferation of blast cells exhibiting megakaryocytic features. Its true incidence remains to be determined. At presentation, many infants are clinically well with only an incidental finding of abnormal blood counts and circulating blasts in the peripheral blood. However, in approximately 20% of cases, the disease is severe and life-threatening, manifesting as hydrops faetalis, multiple effusions, and liver or multi-organ system failure resulting in death. Of those children who enter a spontaneous remission, 13-33% have been found to develop subsequent acute megakaryoblastic leukemia, usually within the first 3 years of life, which if left untreated is fatal. This unique TL of the DS newborn has been the subject of recent clinical cooperative group trials as well as many biological and genetic research efforts. We summarize here the known clinical, biological, and cytogenetic features of TL associated with DS.

High-dose immunoglobulin during pregnancy for recurrent neonatal haemochromatosis

BACKGROUND

Neonatal haemochromatosis is a rare disease of gestation that results in severe fetal liver injury. We hypothesised an alloimmune aetiology for the disorder on the basis of its high recurrence rate in sibships. In this study, we assessed the effectiveness in preventing or changing the severity of recurrent neonatal haemochromatosis of administering during pregnancy high-dose intravenous immunoglobulin (IVIG) derived from pooled serum of multiple donors.

METHODS

Women whose most recent pregnancy ended in documented neonatal haemochromatosis were treated with IVIG, 1 g/kg bodyweight, weekly from the 18th week until the end of gestation in their subsequent pregnancy. The outcomes of treated pregnancies were compared with those of randomly selected previous affected pregnancies for each woman, which were used as historical controls.

FINDINGS

15 women were treated through 16 pregnancies. All pregnancies progressed uneventfully and resulted in live babies with normal physical examinations and birthweights that were appropriate for gestational age. 12 babies had evidence of liver involvement with neonatal haemochromatosis: 11 had higher than normal concentrations of serum alpha-fetoprotein and ferritin or serum alpha-fetoprotein alone, including four with coagulopathy (international normalised ratio >1.5), and one had coagulopathy alone. All babies survived with medical or no treatment and were healthy at follow-up within the past 6 months. In analysis on a per-mother basis comparing outcomes of treated gestations with those of randomly selected previous affected gestations, gestational IVIG therapy was associated with better infant survival (15 good outcomes vs two in previous pregnancies; p=0.0009).

INTERPRETATION

Treatment with high-dose IVIG during gestation appears to have modified recurrent neonatal haemochromatosis so that it was not lethal to the fetus or neonate. These results further support an alloimmune mechanism for recurrent neonatal haemochromatosis.

Congenital Anerythremic Erythroleukemia Presenting as Hepatic Failure

We report an atypical case of congenital erythroleukemia in a child born with hepatosplenomegaly and abnormal liver tests. The initial peripheral blood cell count showed anemia and hyperleukocytosis with erythroblastosis that disappeared 1 week later. During the next 5 weeks, no blasts were found in the blood, and less than 5% were found on 2 successive bone marrow aspirates. The infant died of hepatic failure. The suspected diagnosis on a premortem liver biopsy was confirmed by an autopsy that showed a blastic infiltration in many organs. These cells expressed only erythroid markers glycophorin A and C. Rearrangement of the myeloid lymphoid leukemia gene was not found by fluorescence in situ hybridization. The main differential diagnoses include metabolic diseases, Langerhans histiocytosis, Pepper syndrome, transient myeloproliferative disorder, and leukemoid reactions. Although some of these can be excluded by the pathologist, others require a multidisciplinary confrontation: clinical, biologic, genetic, and pathologic examinations.

Neonatal hemochromatosis

Neonatal hemochromatosis is a rare gestational condition in which iron accumulates in the fetal tissues in a distribution like that seen in hereditary hemochromatosis. Extensive liver damage is the dominant clinical feature, with late fetal loss or early neonatal death. NH recurs within sibships at a rate higher than that predicted for simple Mendelian autosomal-recessive inheritance, possibly suggesting the role of a maternal factor. Immunomodulation during pregnancy at risk appears to lessen the severity of disease.

Fetal and neonatal leukemia

The biological and clinical characteristics of perinatal leukemia differ significantly from those of leukemia in older children, and the prognosis is generally bleak. Once complete remission is achieved, neonates with acute myelocytic leukemia (AML) fare much better than those with acute lymphocytic leukemia (ALL). The results of this study suggest that age, sex, type of leukemia, and cytogenetic findings have a strong influence on outcome. Neonates, particularly females, with pre-B ALL have a much worse prognosis than neonates and older children with this disease. Transient leukemia in the Down syndrome neonate is associated with significant morbidity; close follow-up is recommended for at least the first 3 years of life because of the potential of developing acute leukemia, particularly AMKL (M7). The purpose of this review is to focus on the fetus and neonate in an attempt to determine the various ways leukemia differs clinically and morphologically from the disease occurring in older infants and children and to demonstrate that certain types of leukemia have a poor prognosis compared with those occurring in older children.

Fetal liver hyperechogenicity on sonography may be a serendipitous sign of a transient myeloproliferating disorder

OBJECTIVE

To demonstrate that thorough antenatal and postnatal investigations are helpful in any genetic syndrome.

CASE REPORT

A woman without a specific risk had a finding of hyperechogenic foci at ultrasound. Karyotype on fetal blood was 47, XY+21 and extensive biochemical investigation revealed abnormal liver function. Given the suspicion of a coincidental hepatic compromise, targeted postmortem examination was performed, which showed hepatic fibrosis, megakaryocytes proliferation and invasion of sinusoid capillaries, all suggestive of a transient myeloproliferative disorder.

CONCLUSION

When compared with chorionic villous and amniotic fluid sampling, fetal blood allows the collection of additional data, which may help in understanding the pathological process behind an apparently serendipitous association.

Common diagnostic problems in pediatric liver pathology

The role of the pathologist in dealing with common problems of liver disease in children is likely to change dramatically as the molecular genetic revolution progresses. For example, microchip arrays for genes involved in bile salt synthesis and transport will pinpoint the specific mutations responsible for infantile cholestasis and similar methods will sort out infectious agents of acute and chronic hepatitis. But even as biochemistry, microbiology, and immunology laboratories already provide essential diagnostic information in such settings, informed histopathologic interpretation will continue to guide investigations of etiology and therapeutics and will remain an important medical necessity [95,96,100,102,104].

Hepatic failure with neonatal tissue siderosis of hemochromatotic type in an infant presenting with meconium ileus. Case report and differential diagnosis of the perinatal iron storage disorders

We report on a female preterm infant with hepatic failure and neonatal tissue siderosis of hemochromatotic type diagnosed by using both histochemistry and atomic absorption spectroscopy. The infant presented with meconium ileus, signs of rapidly progressive hepatic failure, and hyperferritinemia (7132 ng/ml). Despite surgery and intensive care the infant died 32 days after birth. Postmortem examination showed a wrinkled liver with extensive collapse of the hepatic architecture and regenerating nodules as well as hepatic and extrahepatic iron accumulation of hemochromatotic type, sparing the reticuloendothelial system. Atomic absorption spectroscopy confirmed an increase in the iron content of various organs: liver, heart, pancreas, oral salivary gland, kidney, and adrenal gland. The increase in the iron content of various organs was determined by comparing the analysis of the propositus with those of 5 gestationally age-related preterm infants who had died in the intensive care unit: 2 died of meconium aspiration syndrome, the other 3 of hyaline membrane disease, bronchopulmonary dysplasia, and immaturity, respectively. We also compared the analysis of 15 fetuses having a a condition predisposing to iron accumulation (trisomy 21, trisomy 18, cytomegalovirus, amnion infection syndrome, Rhesus- and ABO-incompatibility, congenital hemolysis, anti-phospholipid syndrome, congenital heart disease). Delta F508, the most frequent mutation seen in cystic fibrosis patients, was excluded by gene sequencing. Different noxae causing iron accumulation in the neonatal period have led to the statement that neonatal hemochromatosis may collect different etiologies, such as metabolic disorders, infections, chromosomal aberrations, and immunological disorders. In this study, we report the singular evidence of neonatal iron accumulation of hemochromatotic type in an infant presenting with meconium ileus and propose a classification of the neonatal disorders associated with iron accumulation.

Incidence and treatment of potentially lethal diseases in transient leukemia of Down syndrome: Pediatric Oncology Group Study

Transient leukemia (TL or transient myeloproliferative disorder) occurs in approximately 10% of newborn infants with Down syndrome. The disorder is characterized by the presence of megakaryoblasts in the peripheral blood; most cases resolve spontaneously within the first 3 months of life, and the child is well thereafter. However, there are cases in which a severe, potentially lethal form of disease develops, manifesting as hepatic fibrosis or cardiopulmonary failure. Hitherto, the incidence of these severe forms of the disease has not been reported. A prospective study of TL was conducted by the Pediatric Oncology Group (POG Study 9481) in which 48 children with TL were identified. Life-threatening disease occurred in nine patients (19%); seven had hepatic fibrosis and two had cardiopulmonary failure. Five children died of the disease within the first 3 months of life, none of whom received antileukemic therapy. One patient died on day 31 after receiving minimal therapy within 1 day of death. Three children received low-dose cytosine arabinoside (Ara-C) (0.4-1.5 mg/kg every 12 hours for 5 or 7 days). In all these patients, the disease resolved. It is concluded that potentially lethal disease is relatively common in TL, and the available evidence suggests that these diseases are responsive to low-dose Ara-C therapy.

Classification and genetic features of neonatal haemochromatosis: a study of 27 affected pedigrees and molecular analysis of genes implicated in iron metabolism

Neonatal haemochromatosis (NH) is a severe and newly recognised syndrome of uncertain aetiology, characterised by congenital cirrhosis or fulminant hepatitis and widespread tissue iron deposition. NH occurs in the context of maternal disease including viral infection, as a complication of metabolic disease in the fetus, and sporadically or recurrently, without overt cause, in sibs. Although an underlying genetic basis for NH has been suspected, no test is available for predictive analysis in at risk pregnancies. As a first step towards an understanding of the putative genetic basis for neonatal haemochromatosis, we have conducted a systematic study of the mode of transmission of this disorder in a total of 40 infants born to 27 families. We have moreover carried out a molecular analysis of candidate genes (beta(2)-microglobulin, HFE, and haem oxygenases 1 and 2) implicated in iron metabolism. No pathogenic mutations in these genes were identified that segregate consistently with the disease phenotype in multiplex pedigrees. However, excluding four pedigrees with clear evidence of maternal infection associated with NH, a pedigree showing transmission of maternal antinuclear factor and ribonucleoprotein antibodies to the affected infants, and two families with possible matrilineal inheritance of disease in maternal half sibs, a large subgroup of the affected pedigrees point to the inheritance of an autosomal recessive trait. This included 14 pedigrees with affected and unaffected infants and a single pedigree where all four affected infants were the sole offspring of consanguineous but otherwise healthy parents. We thus report three distinct patterns of disease transmission in neonatal haemochromatosis. In the differentiation of a large subgroup showing transmission of disease in a manner suggesting autosomal recessive inheritance, we also provide the basis for further genome wide studies to define chromosomal determinants of iron storage disease in the newborn.

Are hereditary hemochromatosis mutations involved in Alzheimer disease?

Mutations in the class I-like major histocompatibility complex gene called HFE are associated with hereditary hemochromatosis (HHC), a disorder of excessive iron uptake. We screened DNA samples from patients with familial Alzheimer disease (FAD) (n = 26), adults with Down syndrome (DS) (n = 50), and older (n = 41) and younger (n = 52) healthy normal individuals, for two HHC point mutations-C282Y and H63D. Because the apolipoprotein E (ApoE) E4 allele is a risk factor for AD and possibly also for dementia of the AD type in DS, DNA samples were also ApoE genotyped. Chi-squared analyses were interpreted at the 0.05 level of significance without Bonferroni corrections. In the pooled healthy normal individuals, C282Y was negatively associated with ApoE E4, an effect also apparent in individuals with DS but not with FAD. Relative to older normals, ApoE E4 was overrepresented in both males and females with FAD, consistent with ApoE E4 being a risk factor for AD; HFE mutations were overrepresented in males and underrepresented in females with FAD. Strong gender effects on the distribution of HFE mutations were apparent in comparisons among ApoE E4 negative individuals in the FAD and healthy normal groups (P < 0.002). Our findings are consistent with the proposition that among ApoE E4 negative individuals HFE mutations are predisposing to FAD in males but are somewhat protective in females. Further, ApoE E4 effects in our FAD group are strongest in females lacking HFE mutations. Relative to younger normals there was a tendency for ApoE E4 and H63D to be overrepresented in males and underrepresented in females with DS. The possibility that HFE mutations are important new genetic risk factors for AD should be pursued further.

Immunohistochemical study on transforming growth factor-beta1 expression in liver fibrosis of Down's syndrome with transient abnormal myelopoiesis

A case of Down's syndrome associated with liver fibrosis is reported. The fibrosis was diffusely distributed along sinusoids, and an excess of megakaryocytes was also found in the liver. To determine the mechanism of liver fibrosis in Down's syndrome, we immunohistochemically stained the liver with markers of myofibroblast-like cells, antialpha smooth muscle actin antibodies and antidesmin antibodies. The myofibroblast-like cells were found along sinusoids, suggesting that liver fibrosis in Down's syndrome is caused by the myofibroblast-like cells derived from Ito cells/lipocytes. The expression of transforming growth factor (TGF)-betal, which is an important mediator of the activation of lipocytes, was immunohistochemically examined. The accumulation of TGF-betal was observed in cells in the sinusoidal spaces, which involve the intracellular expression of megakaryocytes. Together, these findings suggest that megakaryocyte-derived TGF-betal is one of the likely candidates in the lipocyte activation of liver fibrogenesis in Down's syndrome.

Down syndrome, transient myeloproliferative disorder, and infantile liver fibrosis

BACKGROUND

In neonates, Down syndrome is rarely accompanied by the leukemoid reaction called transient myeloproliferative disorder.

PROCEDURES AND RESULTS

We present clinical and histopathologic data of another Down syndrome neonate with transient myeloproliferative disorder and severe infantile liver fibrosis. These findings in our patients are compared in detail with the 20 cases published previously. Similar clinical and laboratory findings were present in all 21.

CONCLUSIONS

Knowing the cellular mechanism of hepatic fibrosis and its modulation by growth factors (e.g, platelet-derived growth factor), a pathogenetic link between transient myeloproliferative disorder and the development of liver fibrosis in Down syndrome neonates seems probable. An association of this triad of findings no longer appears to be accidental.

Leukemia and/or myeloproliferative syndrome in neonates with Down syndrome

Approximately 10% of newborn infants with Down Syndrome develop a form of megakaryoblastic leukemia which usually disappears spontaneously during the first months of life. The evidence that this "Transient Leukemia" is truly leukemia includes the following: it is clonal proliferation, it can be fatal and tissue infiltration of leukemic cells occurs. Also in approximately 25% of cases that recover, Acute Megakaryoblastic Leukemia will develop in the first four years of life, which, if not treated, is fatal. Evidence regarding the megakaryoblastic nature of the leukemic cells is presented as well as a description of the lethal forms of the disease. The study of Transient Leukemia is of considerable importance because it can provide insight into both the nature of leukemia and its relation to trisomy 21.

Aspects of the neoplasms observed in patients with constitutional autosomal trisomy

A review of the literature reveals numerous clinical case reports, systematic histologic analyses, epidemiologic studies, and large series of tumors showing that subjects with trisomy 8, 9, 13, 18, and 21 have an excess of hematologic and various solid tumors compared to the general population. These tumors more frequently affect particular organs for a given type of trisomy. A large proportion of tumors are observed during fetal and neonatal life, are incompletely developed, and subsequently regress. In older children or even adults, tumors are less frequent, are often found on the same organs as earlier in life, are more aggressive, and do not involute. The mechanism responsible for the development of these neoplasms could be similar to that which generates the malformations in these children and may result from cooperation of the chromosomal abnormality with physiologic growth phenomena, which are particularly active early in life. Trisomic subjects must be carefully followed in order to detect tumors as early as possible and to allow treatment under optimal conditions.

Hydrops fetalis and neonatal leukemia in Down syndrome

Four newborn infants with Down syndrome and manifestations of neonatal leukemia are described. One of the four was stillborn, two died shortly after birth, and a fourth survived and all evidence of leukemia disappeared in the first month of life. Three of the four cases had hydrops fetalis, and a fourth was a macerated stillborn. Nine other similar reported cases are reviewed. We conclude that neonatal leukemia in Down syndrome is a form of leukemia that is usually transient, with spontaneous recovery, but may be fatal at or around the time of birth with manifestations of hydrops fetalis, hepatosplenomegaly, and/or progressive liver disease.

Neonatal haemochromatosis associated with Down syndrome

METHODOLOGY

The clinical course of a child with neonatal haemochromatosis associated with Down syndrome is described, using case notes and post-mortem examination.

RESULTS

The patient died of liver failure on day 36. Post-mortem examination showed siderosis of liver, pancreas, heart, kidney and thyroid.

CONCLUSIONS

Neonatal haemochromatosis is a rare paediatric disease, the aetiology of which is unknown. Evidence suggests a disorder of fetoplacental iron handling with implications for recurrence in future pregnancies.

Renal proximal tubular dysgenesis associated with severe neonatal hemosiderotic liver disease

We report the necropsy findings for three infants with the unusual combination of proximal renal tubular dysgenesis and severe congenital liver disease with excessive iron in several organs resembling neonatal hemochromatosis. Two of the infants were caucasian siblings and one was an Australian aborigine. One died in utero at 35 weeks of gestation and two died at 7 days. The liveborn infants presented with anuria and liver failure. The livers all showed marked loss of hepatocytes and replacement by pseudotubules in the collapsed lobules. The liveborn infants also showed giant cell transformation of hepatocytes, small regenerative nodules, cholestasis, and normal bile ducts. Absence of proximal renal convolutions was confirmed by epithelial membrane antigen positivity in nearly all tubules. In each family there was another sibling with congenital liver disease, fatal in one case, but no renal tubular dysgenesis. No infection or metabolic disease was uncovered in any of our patients, and the cause of the hepatocyte destruction was not determined. The combination in three infants of two rare congenital diseases could be genetic or acquired in utero from the same etiological agent. Alternatively, the absence of proximal convolutions could be secondary to hypoperfusion, perhaps because of shock due to extensive necrosis of hepatocytes.