Neuraminidase deficiency presenting as non-immune hydrops fetalis

Parental Whole-Exome Sequencing Enables Sialidosis Type II Diagnosis due to an NEU1 Missense Mutation as an Underlying Cause of Nephrotic Syndrome in the Child

Introduction

Monogenetic renal diseases, including recessively inherited nephrotic syndromes, represent a significant health burden despite being rare conditions. Precise diagnosis, including identification of the underlying molecular cause, is especially difficult in low-income countries and/or if affected individuals are unavailable for biochemical testing. Whole-exome sequencing (WES) has opened up novel diagnostic perspectives for these settings. However, sometimes the DNA of affected individuals is not suitable for WES due to low amounts or degradation.

Methods

We report on the use of parental WES with implementation of specific stepwise variant filtering to identify the underlying molecular cause of the childhood-onset nephrotic syndrome as nephrosialidosis resulting from a mutation in NEU1.

Results

Sequencing both parents enabled a nephrosialidosis diagnosis in the deceased child. To date, only 16 other cases of nephrosialidosis have been reported in the literature, with only 1 genetically confirmed case. After we reviewed the clinical information of all reported cases, we found that most patients presented with proteinuria, which started at between 2 and 3 years of age. Renal pathology showed mainly focal segmental glomerulosclerosis (FSGS)with vacuolated cells, and steroid treatment was always unsuccessful. Hepatomegaly was present in nearly all cases, whereas corneal clouding and a cherry red spot on the macula was observed in only approximately 50% of cases. Fourteen of 16 previously reported cases were no longer alive at the time of reporting.

Conclusions

Our findings demonstrate the power of parental WES to diagnose rare genetic diseases, such as childhood-onset nephrotic syndrome. We further provide a comprehensive overview of the clinical course of nephrosialidosis and raise awareness of this ultra-rare condition as an underlying cause of FSGS.

Type 1 sialidosis presenting with ataxia, seizures and myoclonus with no visual involvement

Sialidosis is an autosomal recessive lysosomal storage disease caused by pathogenic variants in NEU1 which encodes lysosomal sialidase (neuraminidase 1). Lysosomal neuraminidase catalyzes the removal of terminal sialic acid molecules from glycolipids, glycoproteins and oligosaccharides. Sialidosis is classified into two types, based on phenotype and age of onset. Patients with the milder type 1 typically present late, usually in the second or third decade, with myoclonus, ataxia and visual defects. Type 2 is more severe and presents earlier with coarse facial features, developmental delay, hepatosplenomegaly and dysostosis multiplex. Presentation and severity of the disease are related to whether lysosomal sialidase is inactive or there is some residual activity. Diagnosis is suspected based on clinical features and increased urinary bound sialic acid excretion and confirmed by genetic testing showing pathogenic variants in NEU1. We report a patient with type 1 sialidosis who presented mainly with ataxia and both generalized and myoclonic seizures but no visual involvement. Whole exome sequencing of the proband detected compound heterozygous likely pathogenic variants (S182G and G227R) in NEU1.

Sialidosis: A Review of Morphology and Molecular Biology of a Rare Pediatric Disorder

Sialidosis (MIM 256550) is a rare, autosomal recessive inherited disorder, caused by α-N-acetyl neuraminidase deficiency resulting from a mutation in the neuraminidase gene (NEU1), located on 6p21.33. This genetic alteration leads to abnormal intracellular accumulation as well as urinary excretion of sialyloligosaccharides. A definitive diagnosis is made after the identification of a mutation in the NEU1 gene. So far, 40 mutations of NEU1 have been reported. An association exists between the impact of the individual mutations and the severity of clinical presentation of sialidosis. According to the clinical symptoms, sialidosis has been divided into two subtypes with different ages of onset and severity, including sialidosis type I (normomorphic or mild form) and sialidosis type II (dysmorphic or severe form). Sialidosis II is further subdivided into (i) congenital; (ii) infantile; and (iii) juvenile. Despite being uncommon, sialidosis has enormous clinical relevance due to its debilitating character. A complete understanding of the underlying pathology remains a challenge, which in turn limits the development of effective therapeutic strategies. Furthermore, in the last few years, some atypical cases of sialidosis have been reported as well. We herein attempt to combine and discuss the underlying molecular biology, the clinical features, and the morphological patterns of sialidosis type I and II.

Lysosomal storage disorder in non-immunological hydrops fetalis (NIHF): more common than assumed? Report of four cases with transient NIHF and a review of the literature

Background

Lysosomal storage disorders (LSD) are a rare cause of non immunological hydrops fetalis (NIHF) and congenital ascites. The reported incidence is about 1%. The incidence of idiopathic NIHF is estimated to be about 18%.

Patients and methods

We report four cases with transient hydrops fetalis resulting from LSD and performed a literature review on LSD with NIHF and congenital ascites in combination.

Results

At present, 12 different LSDs are described to be associated with NIHF or congenital ascites. Most patients had a family history of NIHF, where the preceding sibling had not been examined. A diagnostic approach to the fetus with NIHF due to suspected LSD either in utero or postnatal is suggested. Transient forms of NIHF and/or ascites in association with MPS IVA, MPS VII and NPC are described for the first time in this publication.

Conclusions

LSD should be considered in transient hydrops. Enzymatic studies in chorionic villous sample or amniotic cultured cells, once the most common conditions associated with fetal ascites or hydrops have been ruled out, are important. This paper emphasizes the fact that LSD is significantly higher than the estimated 1% in previous studies, which is important for genetic counseling as there is a high risk of recurrence and the availability of enzyme replacement therapy for an increasing number of LSD.

The therapeutic potential of pharmacological chaperones and proteosomal inhibitors, Celastrol and MG132 in the treatment of sialidosis

Sialidosis is an autosomal recessive disorder caused by a dysfunctional Sialidase enzyme. Categorised into two phenotypes, Sialidosis type I and II, Sialidosis is a highly heterogeneous disorder with varying ages of onset and pathologies. Currently, there is no viable therapy for the treatment of Sialidosis patients. At the molecular level, cells from Sialidosis patients with compound heterozygous mutations show improper enzyme folding, loss of Sialidase enzyme activity and subsequent accumulation of sialylconjugates within lysosomes. One promising treatment option is the use of small pharmacological molecules to increase the enzymatic activities of mutant proteins. In this study, we examined the efficacy of the immuno-suppressant (Celastrol) as well as a proteosomal inhibitor (MG132) to rescue mutant enzymes with altered conformation. Our results reveal that MG132 enhances enzyme activity and its localisation in cells expressing defective Sialidase. We also found that MG132 reduces accumulation of ganglioside products, GT1b, GD3, and GM3 in pre-loaded Sialidosis cells. Alternatively, Celastrol appears to reduce Sialidase expression and activity revealing a potentially novel effect of Celastrol on Sialidase. Interestingly, the combination of Celastrol and MG132 appears to amplify the beneficial impact of MG132 on both the endogenous and recombinant expression of defective Sialidase. This study explores a novel biological criteria to assess the efficacy of small molecules through accumulation analysis and points to a potential therapeutic strategy for the treatment of Sialidosis.

Type II sialidosis: review of the clinical spectrum and identification of a new splicing defect with chitotriosidase assessment in two patients

Sialidosis is a lysosomal storage disease caused by the deficiency of alpha-N-acetyl neuraminidase-1 (NEU1). Sialidosis is classified into two main clinical variants: Type I, the milder form of the disease, and Type II, which can in turn be subdivided into three forms: congenital, infantile and juvenile. We report herein the clinical, biochemical and molecular characterisation of two patients with Type II sialidosis exhibiting the congenital (P1) and infantile forms (P2). We also review clinical data on the rare Type II forms of sialidosis in the hope of improving understanding of the disorder and facilitating its diagnosis. The genetic characterization of the two patients showed one known [c. 679G > A (p.G227R)] NEU1 missense mutation (detected in P2), and the new c.807 + 1G > A splicing defect (detected in P1), a genetic lesion that is extremely rare in this disease. Interestingly, P2 presented an extremely elevated level of chitotriosidase in plasma. This is the first pathological detection of chitotriosidase in sialidosis patients.

Lysosomal storage disorders in the newborn

Lysosomal storage disorders are rare inborn errors of metabolism, with a combined incidence of 1 in 1500 to 7000 live births. These relatively rare disorders are seldom considered when evaluating a sick newborn. A significant number of the >50 different lysosomal storage disorders, however, do manifest in the neonatal period and should be part of the differential diagnosis of several perinatal phenotypes. We review the earliest clinical features, diagnostic tests, and treatment options for lysosomal storage disorders that can present in the newborn. Although many of the lysosomal storage disorders are characterized by a range in phenotypes, the focus of this review is on the specific symptoms and clinical findings that present in the perinatal period, including neurologic, respiratory, endocrine, and cardiovascular manifestations, dysmorphic features, hepatosplenomegaly, skin or ocular involvement, and hydrops fetalis/congenital ascites. A greater awareness of these features may help to reduce misdiagnosis and promote the early detection of lysosomal storage disorders. Implementing therapy at the earliest stage possible is crucial for several of the lysosomal storage disorders; hence, an early appreciation of these disorders by physicians who treat newborns is essential.

Recurrent Non-immune Fetal Hydrops: A Case Report

Introduction: Recurrent non-immune fetal hydrops (NIH) has been reported in the literature but is a rare entity, with fewer than 6 reported cases so far. It has been postulated to be related to a recessive gene. Clinical Picture: We report a case of recurrent fetal hydrops in a multigravida with no medical history of note. She presented in her current pregnancy with a significant history of having 4 (out of 7) previous pregnancies affected by hydrops. Treatment: All the affected pregnancies resulted in mid-trimester pregnancy termination (MTPT) following diagnosis in the second trimester. Previous investigations for hydrops did not yield any obvious cause. Outcome: Her most recent pregnancy was unaffected. We discuss the possible differential diagnoses and the likelihood of autosomal recessive metabolic diseases being the aetiological factor. Conclusion: Rare causes of fetal hydrops need to be excluded in cases of recurrent non-immune hydrops with no obvious aetiology following routine investigations. Key words: Hydrops fetalis, Lysosomal storage disorders, Non-immune, Thalassaemia, Ultrasonography

Lysosomal storage diseases in non-immune hydrops fetalis pregnancies

BACKGROUND

At least 20 inborn errors of metabolism may cause hydrops fetalis. Most of these are lysosomal storage diseases. The study proposes a diagnostic flowchart for prenatal diagnosis of non-immune hydrops fetalis.

METHODS

This study contains a series of 75 non-immune hydrops fetalis pregnancies. Mucopolysaccharides, oligosaccharides, neuraminic acid and 21 lysosomal enzymes were measured in amniotic fluid and cultured amniotic cells.

RESULTS

The study gives reference values for mucopolysaccharides and neuraminic acid at various stages of gestation. Four definite and two probable lysosomal diagnoses were found among the 75 investigated cases (=5.3-8%). Fetal death was found to cause false positive values for mucopolysaccharides in amniotic fluid. In the galactosialidosis case, two novel mutations were found in the cathepsin A gene.

CONCLUSIONS

Reference values for mucopolysaccharides and neuraminic acid depend on gestational age. In a relatively high percentage of the hydrops foetalis pregnancies, a lysosomal aetiology is found. This study provides a strategy to diagnose lysosomal diseases in hydrops fetalis pregnancies. Awareness of lysosomal storage diseases causing hydrops fetalis is useful as it gives an opportunity for risk evaluation, genetic counseling to parents and targeted prenatal diagnostics for ensuing pregnancies.

Sialidosis presenting as severe nonimmune fetal hydrops is associated with two novel mutations in lysosomal alpha-neuraminidase

Sialidosis is a lysosomal storage disease characterized by accumulation of sialylated oligosaccharides in tissues, blood and urine and is caused by mutations in the gene for lysosomal alpha-neuraminidase (NEU1). There is wide variability in the age of onset and severity of symptoms in sialidosis. We report here a case of sialidosis due to novel mutations in NEU1 presenting as severe nonimmune hydrops fetalis.

Molecular pathology of NEU1 gene in sialidosis

Lysosomal sialidase (EC 3.2.1.18) has a dual physiological function; it participates in intralysosomal catabolism of sialylated glycoconjugates and is involved in cellular immune response. Mutations in the sialidase gene NEU1, located on chromosome 6p21.3, result in autosomal recessive disorder, sialidosis, which is characterized by the progressive lysosomal storage of sialylated glycopeptides and oligosaccharides. Sialidosis type I is a milder, late-onset, normosomatic form of the disorder. Type I patients develop visual defects, myoclonus syndrome, cherry-red macular spots, ataxia, hyperreflexia, and seizures. The severe early-onset form, sialidosis type II, is also associated with dysostosis multiplex, Hurler-like phenotype, mental retardation, and hepatosplenomegaly. We summarize information on the 34 unique mutations determined so far in the sialidase gene, including four novel missense and one novel nonsense mutations found in two Czech and two French sialidosis patients. The analysis of sialidase mutations in sialidosis revealed considerable molecular heterogeneity, reflecting the diversity of clinical phenotypes that make molecular diagnosis difficult. The majority of sialidosis patients have had missense mutations, many of which have been expressed; their effects on activity, stability, intracellular localization, and supramolecular organization of sialidase were studied. A structural model of sialidase allowed us to localize mutations in the sialidase molecule and to predict their impact on the tertiary structure and biochemical properties of the enzyme.

Genetics of epilepsy: current status and perspectives

Epilepsy affects more than 0.5% of the world's population and has a large genetic component. The most common human genetic epilepsies display a complex pattern of inheritance and the susceptibility genes are largely unknown. However, major advances have recently been made in our understanding of the genetic basis of monogenic inherited epilepsies. Progress has been particularly evident in familial idiopathic epilepsies and in many inherited symptomatic epilepsies, with the discovery that mutations in ion channel subunits are implicated, and direct molecular diagnosis of some phenotypes of epilepsy is now possible. This article reviews recent progress made in molecular genetics of epilepsy, focusing mostly on idiopathic epilepsy, and some types of myoclonus epilepsies. Mutations in the neuronal nicotinic acetylcholine receptor alpha4 and beta2 subunit genes have been detected in families with autosomal dominant nocturnal frontal lobe epilepsy, and those of two K(+) channel genes were identified to be responsible for underlying genetic abnormalities of benign familial neonatal convulsions. The voltage-gated Na(+) -channel (alpha1,2 and beta1 subunit), and GABA receptor (gamma2 subunit) may be involved in the pathogenesis of generalized epilepsy with febrile seizure plus and severe myoclonic epilepsy in infancy. Mutations of Ca(2+)-channel can cause some forms of juvenile myoclonic epilepsy and idiopathic generalized epilepsy. Based upon these findings, pathogenesis of epilepsy as a channelopathy and perspectives of molecular study of epilepsy are discussed.

Lysosomal multienzyme complex: biochemistry, genetics, and molecular pathophysiology

Lysosomal enzymes sialidase (alpha-neuraminidase), beta-galactosidase, and N-acetylaminogalacto-6-sulfate sulfatase are involved in the catabolism of glycolipids, glycoproteins, and oligosaccharides. Their functional activity in the cell depends on their association in a multienzyme complex with lysosomal carboxypeptidase, cathepsin A. We review the data suggesting that the integrity of the complex plays a crucial role at different stages of biogenesis of lysosomal enzymes, including intracellular sorting and proteolytic processing of their precursors. The complex plays a protective role for all components, extending their half-life in the lysosome from several hours to several days; and for sialidase, the association with cathepsin A is also necessary for the expression of enzymatic activity. The disintegration of the complex due to genetic mutations in its components results in their functional deficiency and causes severe metabolic disorders: sialidosis (mutations in sialidase), GM1-gangliosidosis and Morquio disease type B (mutations in beta-galactosidase), galactosialidosis (mutations in cathepsin A), and Morquio disease type A (mutations in N-acetylaminogalacto-6-sulfate sulfatase). The genetic, biochemical, and direct structural studies described here clarify the molecular pathogenic mechanisms of these disorders and suggest new diagnostic tools.

Mutations in sialidosis impair sialidase binding to the lysosomal multienzyme complex

Sialidosis is an autosomal recessive disease caused by the genetic deficiency of lysosomal sialidase, which catalyzes the catabolism of sialoglycoconjugates. The disease is associated with progressive impaired vision, macular cherry-red spots, and myoclonus (sialidosis type I) or with skeletal dysplasia, Hurler-like phenotype, dysostosis multiplex, mental retardation, and hepatosplenomegaly (sialidosis type II). We analyzed the effect of the missense mutations G68V, S182G, G227R, F260Y, L270F, A298V, G328S, and L363P, which are identified in the sialidosis type I and sialidosis type II patients, on the activity, stability, and intracellular distribution of sialidase. We found that three mutations, F260Y, L270F, and A298V, which are clustered in the same region on the surface of the sialidase molecule, dramatically reduced the enzyme activity and caused a rapid intralysosomal degradation of the expressed protein. We suggested that this region might be involved in sialidase binding with lysosomal cathepsin A and/or beta-galactosidase in the multienzyme lysosomal complex required for the expression of sialidase activity. Transgenic expression of mutants followed by density gradient centrifugation of cellular extracts confirmed this hypothesis and showed that sialidase deficiency in some sialidosis patients results from disruption of the lysosomal multienzyme complex.

Prenatal diagnosis of lysosomal storage diseases using fetal blood

Lysosomal storage diseases are a rare but significant cause of non-immune hydrops fetalis (NIHF). In 17 cases of NIHF detected by ultrasound, the activity of five lysosomal enzymes was measured in leukocytes or plasma of 1 ml of fetal blood obtained by cordocentesis. By this approach seven lysosomal storage diseases known to present with hydrops fetalis can be diagnosed. In this series one case of mucopolysaccharidosis VII (M. Sly) was diagnosed at 20 weeks' gestation. The other samples allowed the establishment of reference ranges for lysosomal enzymes associated with NIHF in fetal blood. We conclude that, also in view of the poor prognosis of lysosomal storage diseases presenting with hydrops fetalis, the use of fetal blood for the early and fast biochemical diagnosis of these diseases is a valuable supplement in the diagnostic work-up and the management of NIHF.

Prenatal diagnosis of lysosomal storage diseases

The prenatal diagnosis of lysosomal storage disorders can be achieved, once the diagnosis is confirmed in the index case, by a variety of techniques including analysis of amniotic fluid, asay of enzymic activity in cultured amniotic fluid cells, cultured chorionic villus cells and by direct assay of activity in chorionic villus samples. These studies can be accompanied by ultrastructural observations which give an independent means of diagnosis. In some instances molecular genetic studies for mutation detection or linkage analysis are appropriate for prenatal diagnosis. Pseudodeficiencies of some of the lysosomal enzymes, which cause no clinical problems, can complicate the initial diagnosis particularly in metachromatic leucodystrophy where the pseudodeficiency is more common than the disease itself. Mutation analysis as well as enzyme assay is necessary not only in the index case but also in the parents before the same techniques are applied to a sample for prenatal diagnosis. A large number of lysosomal storage disorders may present as fetal hydrops and the diagnosis can be established at this late stage by fetal blood sampling and examination by microscopy as well as by biochemical assay of the appropriate enzyme or metabolite in amniotic fluid. All prenatal diagnoses in which an affected fetus is indicated should have confirmation of the diagnosis as soon as possible to reassure anxious parents, and to act as audit of the laboratory's competence to undertake prenatal diagnosis. A combined approach to prenatal diagnosis involving biochemical, molecular genetic and morphological studies is recommended.

Cloning, expression and chromosomal mapping of human lysosomal sialidase and characterization of mutations in sialidosis

Sialidase (neuraminidase, EC 3.2.1.18) catalyses the hydrolysis of terminal sialic acid residues of glyconjugates. Sialidase has been well studied in viruses and bacteria where it destroys the sialic acid-containing receptors at the surface of host cells, and mobilizes bacterial nutrients. In mammals, three types of sialidases, lysosomal, plasma membrane and cytosolic, have been described. For lysosomal sialidase in humans, the primary genetic deficiency results in an autosomal recessive disease, sialidosis, associated with tissue accumulation and urinary excretion of sialylated oligosaccharides and glycolipids. Sialidosis includes two main clinical variants: late-onset, sialidosis type I, characterized by bilateral macular cherry-red spots and myoclonus, and infantile-onset, sialidosis type II, characterized by skeletal dysplasia, mental retardation and hepatosplenomegaly. We report the identification of human lysosomal sialidase cDNA, its cloning, sequencing and expression. Examination of six sialidosis patients revealed three mutations, one frameshift insertion and two missense. We mapped the lysosomal sialidase gene to human chromosome 6 (6p21.3), which is consistent with the previous chromosomal assignment of this gene in proximity to the HLA locus.

Neuraminidase deficiency presenting as a nephrosialidosis: the first case detected in Poland

A defect of lysosomal neuraminidase (sialidase N-acetyl-neuramine acid hydrolase EC 3.2.1.18) leads to a wide spectrum of phenotypes, the most severe of which is nephrosialidosis. A 4-year-old boy of related parents, born at term with hydrops fetalis, is reported. Hydrocephalus was detected at 2 months of age. The child's course over 3 years was characterized by slow growth and psychomotor development. He had mild hepatosplenomegaly, joint restriction, gingival hypertrophy, lens opacities and cherry-red spot. Coarse facial features and depressed nasal bridge were discreet. At the age of 3.5 years, he developed gradual progressive edema, decreased activity and increased fatigue. A diagnosis of nephrotic syndrome was made because of massive proteinuria. Thin-layer chromatography of urinary oligosaccharides revealed the presence of several abnormal sialyloligosaccharides. The diagnosis was confirmed by measurement of neuraminidase activity in cultured skin fibroblasts.

Neuraminidase assay in cultured human fibroblasts: in situ versus in vitro procedures

Further investigations have been carried out to characterize a published procedure of neuraminidase assay, in which the activity is measured directly on the cell culture layer. The pH optimum was 4.0. A Vmax value of 130 nmol/mg/h and a K(m) of 0.3 mmol/l were found. During incubation in the acid buffer, arylsulphatase activity was released into the medium, whereas neuraminidase activity remained attached to the cells. The in situ method allowed an unequivocal diagnosis of primary and secondary neuraminidase deficiencies. Because of its simplicity and reliability, the method appears useful as a routine method in clinical laboratories.

Hydrops fetalis: role of the geneticist

The causes of hydrops fetalis are myriad. As a result of the advent of routine Rh screening, most cases are not currently related to Rh incompatibility. Genetic, metabolic, chromosomal, and syndromic causes are among the most frequently identified causes of nonimmune hydrops. The importance of determining the underlying cause of hydrops becomes evident once issues such as prognosis, specific treatment, and risk of recurrence are considered. The medical geneticist is highly qualified to assist in the evaluation of hydrops. Clinical geneticists have undergone training in a primary care specialty followed by intensive training in the diagnosis, management, and counseling of individuals and families with genetic, chromosomal, or multifactorial syndromes or birth defects. This training prepares the medical geneticist well to serve as a consultant when hydrops is diagnosed. As knowledge of the molecular genetic and metabolic basis of disease increases, utilization of genetics laboratories continues to increase dramatically. In addition to examining the child to look for dysmorphic features, the clinical geneticist can assist with the laboratory evaluation by coordinating testing with the cytogeneticist, molecular geneticist, and biochemical geneticist as appropriate. Increased awareness of the role of the geneticist in the evaluation of such patients should prove helpful to the physicians caring for such patients and the patients' families.

Screening for lysosomal disorders

Patients at any age who develop regression of learned skills, onset of dementia, loss of motor control and organ enlargement should be considered for lysosomal screening. Morphological and biochemical screening methods may reinforce the clinical suspicion, but they are not diagnostic. A widespread use of enzyme assays that appear to be related to the clinical problems is recommended.

Prenatal diagnosis of congenital sialidosis

A case of prenatally diagnosed congenital sialidosis is described in a 21-week-old male fetus, which was the fifth product of non-consanguineous parents. The proband, the second product, was diagnosed as having sialidosis by the enzyme assay in peripheral leukocytes after birth. At the 17th week of pregnancy, the fetus at risk was proven to have isolated sialidase deficiency after analyzing a sample of the cultured amniotic fluid cells. There were many cytoplasmic vacuoles and increased amounts of sialyloligosaccharides in the tissue of the aborted fetus, while the amount and the pattern of gangliosides in the central nervous system were normal.

Frequency of the delta F508 and exon 11 mutations in Norwegian cystic fibrosis patients

We have searched for the delta F508 mutation in 77 Norwegian cystic fibrosis patients. Of the 154 chromosomes tested, 93 (60%) carried the delta F508 mutation. Haplotypes at the D7S23 locus (KM19 and XV2C markers) were determined. Of 81 chromosomes with the F508 mutation, the B haplotype was found on 77. We found three patients with the G551D and one patient with the R553X mutation in exon 11 of the CFTR locus.

Foamy changes of placental cells in probable beta glucuronidase deficiency associated with hydrops fetalis

Mucopolysaccharidosis type VII (MPS VII, beta glucuronidase deficiency) has been described in association with non-immune hydrops fetalis. Three consecutive pregnancies in an itinerant family, which resulted in stillbirths caused by non-immune hydrops are described. The parents were closely related and there was a strong family history of storage disorders. The main clue to the diagnosis, however, came from the presence of pronounced foamy cytoplasmic change in the villous Hofbauer cells of the placenta. This raised the possibility of an inherited metabolic storage disorder. The parents were subsequently shown to have beta glucuronidase activities in the heterozygous range in leucocytes and fibroblasts which suggested that the non-immune hydrops was caused by beta glucuronidase deficiency.

Fetal presentation of Morquio disease type A

A fetus with mucopolysaccharidosis type IV A (Morquio type A) is described. The family had one affected child exhibiting symptoms of classical Morquio A disease, and late in the subsequent pregnancy prenatal diagnosis was requested. At 23 weeks' gestation, moderate ascites was detected by detailed ultrasound scan and keratan sulphate was found in the amniotic fluid. The pregnancy was terminated by prostaglandin induction and the diagnosis of mucopolysaccharidosis type IV A was confirmed by demonstration of a deficiency of N-acetylgalactosamine-6-sulphate (GalNac-6-S) sulphatase in cultured amniotic cells and in post-mortem fibroblast cultures. The activities of beta-galactosidase and arylsulphatase A were normal, ruling out Morquio disease type B and multiple sulphatase deficiency. These results indicate that mucopolysaccharidosis IV A (a disease that predominantly affects the skeletal system) may produce ascites in the fetus to such an extent that it can be detected by ultrasound.

Mucopolysaccharidosis VII as cause of fetal hydrops in early pregnancy

We report on fetal hydrops presenting at 18 weeks of gestation and diagnosed as beta-glucuronidase deficiency. The parents were first cousins and there were 2 previous similar fetal deaths. beta-Glucuronidase was absent in cultured fetal fibroblasts and lymphoblasts but was normal in the tested relatives. The activities of other lysosomal enzymes were normal.

Colour Doppler imaging of intracranial vasculopathy in severe infantile sialidosis

Neonatal ascites is usually attributed to prenatal infections, lysosomal storage disease and anomalies of the genitourinary tract, gastrointestinal tract or cardiovascular system. We report one case of neonatal ascites associated with infantile sialidosis. Cerebral sonography showed stripe-like intracerebral echogenicities in the region of the basal ganglia. Colour Doppler imaging demonstrated blood flow within the echogenicities confirming the suspected diagnosis of intracranial vasculopathy.

Niemann-Pick disease associated with nonimmune hydrops fetalis

The number of metabolic disorders associated with nonimmune hydrops fetalis is very small and includes only Gaucher disease, GM1 gangliosidosis type 1, Hurler syndrome, and mucolipidosis type I. We report another association of a nonimmune hydrops fetalis with Niemann-Pick disease as evident by electron microscopy, and wish to add this disorder to the list of conditions associated with nonimmune hydrops fetalis.

Hydrops revisited: literature review of 1,414 cases published in the 1980s

This paper reviews 47 series of hydrops fetalis (804 cases) and 610 individual cases published since 1980. From this large number of cases, guidelines are derived for prenatal diagnosis and management.

Infantile sialic acid storage disease associated with renal disease

A child with infantile sialic acid storage disease is reported. Ultrasonography demonstrated fetal ascites. At birth, the infant appeared hydropic and presented with numerous dysmorphic features, including sparse white hair, coarse facies, hypertelorism, epicanthal folds, anteverted nostrils, and a long philtrum. In addition, he had visceromegaly, bilateral inguinal hernias, and a slight gibbus deformity. Lymphocytes were vacuolated and bone marrow contained large numbers of foam cells. There were generalized vacuolations of both reticuloendothelial and parenchymal cells in the examined tissues. Neuropathologic studies revealed wide-spread neuronal storage, myelin loss, axonal spheroids, and gliosis. Neurons, endothelial cells, and Kupffer cells stained with wheat germ agglutinin indicated an accumulation of sialic acid. Free sialic acid was significantly increased in urine and serum, as well as in liver, heart, and brain tissues. The alpha-neuraminidase activity was normal. It is assumed that the basic defect of infantile sialic acid storage disease lies in impaired transport of sialic acid across the lysosomal membrane.

Genetic mucopolysaccharidoses, mannosidosis, sialidosis, galactosialidosis, and I-cell disease. Ultrastructural analysis of cultured fibroblasts

The cultured skin fibroblasts biopsied from 6 cases of galactosialidosis, 4 of I-cell disease, 3 of Scheie syndrome and one of Sanfilippo B syndrome, Morquio A syndrome, sialidosis, and mannosidosis, respectively, were investigated electron microscopically to detect any cytoplasmic storage inclusions. In the cases of genetic mucopolysaccharidosis, vacuolar inclusions containing fine reticulogranular materials of low electron density predominated, showing no significant difference in fine structure among the Sanfilippo B syndrome, Scheie syndrome, and Morquio A syndrome. Similar storage inclusions were observed in sialidosis and mannosidosis and also revealed no obvious difference among the diseases and the above-mentioned syndromes of genetic mucopolysaccharidosis. In galactosialidosis, two types of inclusions, vacuolar and lamellar, were distinguished, resembling those usually seen in generalized gangliosidosis. In I-cell disease, the cytoplasmic storage inclusions were variegated; vacuolar, concentric lamellar or osmiophilic amorphous. The availability of electron microscopy in tissue culture is discussed for making the diagnosis of these diseases, and the pathogenesis of lysosomal storage inclusions in the cultured cells of the diseases is briefly viewed.

Morquio disease presenting as hydrops fetalis and enzyme analysis of chorionic villus tissue in a subsequent pregnancy

We describe the prenatal diagnosis of a fetus at risk for mucopolysaccharidosis (MPS) Type IVA (Morquio syndrome) using enzyme analysis of chorionic villus tissue. The family had two previous affected children, one with progressive nonimmune hydrops fetalis presenting at 16 weeks gestation and one mildly affected 5 year old. The parents had decreased levels of N-acetyl galactosamine-6-sulphate sulphatase in cultured skin fibroblasts indicating that carrier detection is possible for Morquio A syndrome.

Primary (genetic) cardiomyopathies in infancy. A survey of possible disorders and guidelines for diagnosis

This is a survey of genetic metabolic diseases in which cardiomyopathy is typical or can be the leading symptom in infancy. Apart from the well-known Pompe disease, several other storage disorders, mitochondrial disorders, and miscellaneous conditions (particularly the carnitine deficiency syndromes) may be seen in this way. Since prompt diagnosis may be mandatory for genetic counselling, and sometimes for specific treatment, guidelines for clinical, cardiological, and laboratory work-up are given.