The clinical, molecular, and pathological characterisation of a family with two cases of lethal perinatal type 2 Gaucher disease

Perinatal lethal form Gaucher disease with compound heterozygosity of single nucleotide variants and copy number variations presenting as nonimmune hydrops fetalis and cerebellar hypoplasia: A case report

OBJECTIVE

To present the ultrasound imaging and genetic diagnosis of a fetus with prenatal lethal form of Gaucher disease.

CASE REPORT

A 37-year-old primiparous woman was pregnant at her 23 weeks of gestation and the prenatal fetal ultrasound revealed hydrops fetalis, cerebellum hypoplasia, and fetal immobility. The pregnancy was terminated due to major fetal anomaly, and whole exome sequencing (WES) analysis of fetal tissue and parental blood unveiled a pathogenic variant in exon 10 of the GBA gene (NM_001005741.3: c.1265T > G: p.L422R) originating from the mother. Additionally, a novel CNV (chr1: 155204785-155205635 deletion, 0.85 kb) spanning exon 10-12 in the GBA gene was identified from the father. This compound heterozygosity confirmed the diagnosis of prenatal lethal form of Gaucher disease and was informative for genetic counseling.

CONCLUSION

WES is a powerful tool to detect pathogenic variants among fetuses with nonimmune hydrops fetalis and complex abnormality from prenatal ultrasound. Compound heterozygosity consisted of single nucleotide variants (SNV) and copy number variations (CNVs) may lead rare inherited metabolic disorders including prenatal lethal form of Gaucher disease.

Congenital Ichthyosis: Current Approaches to Prenatal Diagnoses

INTRODUCTION

Congenital ichthyosis represents a wide spectrum of diseases. This article reviews prenatal testing for ichthyosis.

METHODS

We used pubmed.ncbi.nlm.nih.gov to search for 38 types of congenital ichthyosis combined with 17 words related to prenatal testing.

RESULTS

Search resulted in 408 publications covering 13 types of ichthyoses and four types of tests.

DISCUSSION

Biochemical testing is diagnostic in trichothiodystrophy, but nonspecific in X-linked ichthyosis and Refsum syndrome. Except in X-linked ichthyosis, biochemical testing requires invasive procedures to obtain fetal skin biopsy, amniocytes, or chorionic villus samples. It is superior to histological and cytological examination of fetal skin biopsy or amniocytes because keratinization occurs later in pregnancy and microscopy cannot differentiate between ichthyosis types. Imaging is more acceptable due to noninvasiveness and routine use, although ultrasonography is operator-dependent, nonspecific, and captures abnormalities at late stage. Molecular tests are described in at-risk pregnancies but testing of free fetal DNA was not described.

Perinatal lethal Gaucher disease: A case report and review of literature

Perinatal lethal Gaucher disease is a very rare variant of type 2 Gaucher disease that occurs in the neonatal period and leads to death in early infancy. The disease is characterized by hydrops fetalis or a collodion baby phenotype accompanied with progressive neurological manifestations, hepatosplenomegaly, thrombocytopenia, anemia, and failure to thrive. We report a case of perinatal lethal Gaucher disease treated with enzyme replacement therapy (ERT) who survived for 9 months and present a literature review of perinatal lethal Gaucher disease cases. The prognosis of perinatal lethal Gaucher disease is poor, and ERT is only effective in visceral manifestation. Therefore, palliative care should be recognized as a treatment option, and ERT employment needs to be discussed in this context.

Ichthyosis

The ichthyoses are a large, heterogeneous group of skin cornification disorders. They can be inherited or acquired, and result in defective keratinocyte differentiation and abnormal epidermal barrier formation. The resultant skin barrier dysfunction leads to increased transepidermal water loss and inflammation. Disordered cornification is clinically characterized by skin scaling with various degrees of thickening, desquamation (peeling) and erythema (redness). Regardless of the type of ichthyosis, many patients suffer from itching, recurrent infections, sweating impairment (hypohidrosis) with heat intolerance, and diverse ocular, hearing and nutritional complications that should be monitored periodically. The characteristic clinical features are considered to be a homeostatic attempt to repair the skin barrier, but heterogeneous clinical presentation and imperfect phenotype-genotype correlation hinder diagnosis. An accurate molecular diagnosis is, however, crucial for predicting prognosis and providing appropriate genetic counselling. Most ichthyoses severely affect patient quality of life and, in severe forms, may cause considerable disability and even death. So far, treatment provides only symptomatic relief. It is lifelong, expensive, time-consuming, and often provides disappointing results. A better understanding of the molecular mechanisms that underlie these conditions is essential for designing pathogenesis-driven and patient-tailored innovative therapeutic solutions.

Establishment and Phenotypic Analysis of the Novel Gaucher Disease Mouse Model With the Partially Humanized Gba1 Gene and F213I Mutation

Gaucher disease (GD) is an autosomal recessive lysosomal storage disorder caused by mutations in the GBA1 gene, which produces the glucocerebrosidase (GCase) protein. There are more than 500 mutations reported in GBA1, among which L444P (p.Leu444Pro) and F213I (p.Phe213Ile) are the most common in the Chinese population, while the function of F213I mutation remains elusive. This study aims to establish the GD mouse model of partially humanized Gba1 gene with F213I mutation. In vitro GCase activity assays showed that the product of partially humanized Gba1 gene, in which the mouse exons 5-7 were replace by the corresponding human exons, displayed similar activity with the wild-type mouse Gba1, while the F213I mutation in the humanized Gba1 led to significant decrease in enzyme activity. ES cell targeting was used to establish the mice expressing the partially humanized Gba1-F213I. Gba1^F213I/+ mice did not show obviously abnormal phenotypes, but homozygous Gba1^F213I/F213I mice died within 24 h after birth, whose epidermal stratum corneum were abnormal from the wild-type. The GCase activity in Gba1^F213I/F213I mice greatly decreased. In conclusion, our results showed that the partially humanized GD mouse model with the F213I mutation was developed and homozygous F213I mutation is lethal for newborn mice.

[Perinatal lethal Gaucher disease. Case report]

The paper describes a case of a perinatal lethal Gaucher disease in a 29-week-old fetus with non-immune hydrops, facial dysmorphia, hepatosplenomegaly, and hypoplasia of cerebellum and pons. Gaucher cells were found in the lymph nodes, spleen, lungs, thymus, cerebellum, and bone marrow. No storage cells have been detected in the placenta. There was a significant placental weight increase due to swelling. The diagnosis of Gaucher disease was confirmed by biochemical analysis (deficiency of glucocerebrosidase activity and sharply increased hexanoylsphingosine concentration) and molecular genetic techniques (the presence of two mutations of the GBA gene). Our observation shows that characteristic histologic signs of disease can be detected at early stages of development.

Lysosomal storage diseases

Lysosomes are cytoplasmic organelles that contain a variety of different hydrolases. A genetic deficiency in the enzymatic activity of one of these hydrolases will lead to the accumulation of the material meant for lysosomal degradation. Examples include glycogen in the case of Pompe disease, glycosaminoglycans in the case of the mucopolysaccharidoses, glycoproteins in the cases of the oligosaccharidoses, and sphingolipids in the cases of Niemann-Pick disease types A and B, Gaucher disease, Tay-Sachs disease, Krabbe disease, and metachromatic leukodystrophy. Sometimes, the lysosomal storage can be caused not by the enzymatic deficiency of one of the hydrolases, but by the deficiency of an activator protein, as occurs in the AB variant of GM2 gangliosidosis. Still other times, the accumulated lysosomal material results from failed egress of a small molecule as a consequence of a deficient transporter, as in cystinosis or Salla disease. In the last couple of decades, enzyme replacement therapy has become available for a number of lysosomal storage diseases. Examples include imiglucerase, taliglucerase and velaglucerase for Gaucher disease, laronidase for Hurler disease, idursulfase for Hunter disease, elosulfase for Morquio disease, galsulfase for Maroteaux-Lamy disease, alglucosidase alfa for Pompe disease, and agalsidase alfa and beta for Fabry disease. In addition, substrate reduction therapy has been approved for certain disorders, such as eliglustat for Gaucher disease. The advent of treatment options for some of these disorders has led to newborn screening pilot studies, and ultimately to the addition of Pompe disease and Hurler disease to the Recommended Uniform Screening Panel (RUSP) in 2015 and 2016, respectively.

The clinical management of Type 2 Gaucher disease

Gaucher disease, the inherited deficiency of the enzyme glucocerebrosidase, is the most common of the lysosomal storage disorders. Type 2 Gaucher disease, the most severe and progressive form, manifests either prenatally or in the first months of life, followed by death within the first years of life. The rarity of the many lysosomal storage disorders makes their diagnosis a challenge, especially in the newborn period when the focus is often on more prevalent illnesses. Thus, a heightened awareness of the presentation of these rare diseases is necessary to ensure their timely consideration. This review, designed to serve as a guide to physicians treating newborns and infants with Gaucher disease, discusses the presenting manifestations of Type 2 Gaucher disease, the diagnostic work-up, associated genotypes and suggestions for management. We also address the ethical concerns that may arise with this progressive and lethal disorder, since currently available treatments may prolong life, but do not impact the neurological manifestations of the disease.

Glucosidase acid beta gene mutations in Egyptian children with Gaucher disease and relation to disease phenotypes

INTRODUCTION

More than 200 mutations have been found in patients with Gaucher disease (GD) and some mutations usually have a high frequency in certain populations. Genotype/phenotype correlation in patients with GD has not been established. This study was designed to determine underlying mutations in Egyptian children with GD and to assess their relation to disease phenotypes.

METHODS

This study comprised 17 patients with GD and 10 healthy controls. Thirteen patients were type 1 GD, 2 type 2, and 2 type 3. DNA was extracted from peripheral blood leukocytes. Exons 9 and 10 were amplified by polymerase chain reaction, and deoxyribonucleic acid sequencing was done with an ABI 310 genetic analyzer.

RESULTS

Wild type allele was detected in 95% (19/20) and a normal variant in 5% (1/20) of controls. L444P allele was encountered in 50% (13/26) of the alleles in type 1 patients, H451P in 7.7% (2/26) and recombinant alleles (RecNcil, RecNcil + M450L, RecFs, RecFs + M450L) in 34.6% (9/26). L444P and Rec alleles each occurred in 50% (2/4) of type 2 and 3 patients. A new mutation was seen in this study {g.7336A>C, (M450L)} and 2 mutant alleles were not determined. Type 1 GD patients had L444P/L444P genotype (23.1%) and Rec alleles/L444P (53.8%), while type 2 and 3 GD patients had Rec alleles/L444P genotypes (100%) with a poor phenotype/genotype correlation.

CONCLUSIONS

L444P and Rec alleles are common in the studied patients. Novel mutations are continuously detected, adding to the expanding panel of GD mutations. No significant genotype-phenotype association was observed.

Type 2 Gaucher disease: phenotypic variation and genotypic heterogeneity

Gaucher disease (GD), the most common lysosomal storage disease, results from a deficiency of the lysosomal enzyme glucocerebrosidase. GD has been classified into 3 types, of which type 2 (the acute neuronopathic form) is the most severe, presenting pre- or perinatally, or in the first few months of life. Traditionally, type 2 GD was considered to have the most uniform clinical phenotype when compared to other GD subtypes. However, case studies over time have demonstrated that type 2 GD, like types 1 and 3, manifests with a spectrum of phenotypes. This review includes case reports that illustrate the broad range of clinical presentations encountered in type 2 GD, as well as a discussion of associated manifestations, pathological findings, diagnostic techniques, and a review of current therapies. While type 2 GD is generally associated with severe mutations in the glucocerebrosidase gene, there is also significant genotypic heterogeneity.

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.

No evidence for activation of the unfolded protein response in neuronopathic models of Gaucher disease

Gaucher disease (GD), the most common lysosomal storage disorder (LSD), is caused by defects in the activity of the lysosomal enzyme, glucocerebrosidase, resulting in intracellular accumulation of glucosylceramide (GlcCer). Neuronopathic forms, which comprise only a small percent of GD patients, are characterized by neurological impairment and neuronal cell death. Little is known about the pathways leading from GlcCer accumulation to neuronal death or dysfunction but defective calcium homeostasis appears to be one of the pathways involved. Recently, endoplasmic reticulum stress together with activation of the unfolded protein response (UPR) has been suggested to play a key role in cell death in neuronopathic forms of GD, and moreover, the UPR was proposed to be a common mediator of apoptosis in LSDs (Wei et al. (2008) Hum. Mol. Genet. 17, 469-477). We now systematically examine whether the UPR is activated in neuronal forms of GD using a selection of neuronal disease models and a combination of western blotting and semi-quantitative and quantitative real-time polymerase chain reaction. We do not find any changes in either protein or mRNA levels of a number of typical UPR markers including BiP, CHOP, XBP1, Herp and GRP58, in either cultured Gaucher neurons or astrocytes, or in brain regions from mouse models, even at late symptomatic stages. We conclude that the proposition that the UPR is a common mediator for apoptosis in all neurodegenerative LSDs needs to be re-evaluated.

Dependence of reversibility and progression of mouse neuronopathic Gaucher disease on acid beta-glucosidase residual activity levels

Genetic and chemically induced neuronopathic mouse models of Gaucher disease were developed to facilitate understanding of the reversibility and/or progression of CNS involvement. The lethality of the skin permeability barrier defect of the complete gene knock out [gba, (glucocerebrosidase) GCase] was avoided by conditional reactivation of a low activity allele (D409H) in keratinocytes (kn-9H). In kn-9H mice, progressive CNS disease and massive glucosylceramide storage in tissues led to death from CNS involvement by the age of 14 days. Conduritol B epoxide (CBE, a covalent inhibitor of GCase) treatment (for 8-12 days) of wild type, D409H, D409V or V394L homozygotes recapitulated the CNS phenotype of the kn-9H mice with seizures, tail arching, shaking, tremor, quadriparesis, extensive neuronal degeneration loss and apoptosis, and death by the age of 14 days. Minor CNS abnormalities occurred after daily CBE injections of 100 mg/kg/day for 6 doses, but neuronal degeneration was progressive and glucosylceramide storage persisted in D409V homozygotes in the 2 to 5 months after CBE cessation; wild type and D409H mice had persistent neurological damage without progression. The persistent CNS deterioration, histologic abnormalities, and glucosylceramide storage in the CBE-treated D409V mice revealed a threshold level of GCase activity necessary for the prevention of progression of CNS involvement.

Gaucher disease: The importance of early diagnosis and therapy

A Gaucher-kór a leggyakoribb lizoszomális tárolási betegség, amelyet a glukocerebrozidáz nevű lizoszomális enzim elégtelen működése okoz. A nemzetközi Gaucher-regiszterben 2006 végén 4584 beteget tartottak nyilván, közülük 34 volt magyar. A betegségnek három típusa van: nem neuropathiás (1. típus), akut neuropathiás (2. típus) és krónikus neuropathiás (3. típus). Ezek közül a nem neuropathiás típus a leggyakoribb, amelynek klinikai megjelenési formái nagy változatosságot mutatnak, és a tünetek a betegek több mint felében tízéves kor előtt jelentkeznek. A gyermekkori manifesztáció rendszerint súlyosabb fenotípusra utal, az irreverzíbilis komplikációk kialakulásának a veszélye nagy. A biztonságos és hatékony enzimszubsztitúciós kezelést 1991 óta alkalmazzák, Magyarországon 1992 óta elérhető. Az optimális dózisban történő korai kezelés megállítja a betegség progresszióját, a korábban kialakult visceralis és hematológiai eltérésekben regressziót idéz elő, megelőzi az irreverzíbilis csontelváltozások kialakulását, és biztosítja a betegek jó életminőségét. A szerzők három, korai gyermekkorban diagnosztizált Gaucher-kóros betegük kórtörténetét mutatják be. Felhívják a figyelmet a korai diagnózis és az irreverzíbilis komplikációk kialakulása előtt elkezdett kezelés fontosságára. A kórkép időben történő felismerése nagy kihívást jelent a gyermekgyógyászok számára.

Perinatal lethal phenotype with generalized ichthyosis in a type 2 Gaucher disease patient with the [L444P;E326K]/P182L genotype: effect of the E326K change in neonatal and classic forms of the disease

Gaucher disease, the most common lysosomal storage disorder, encompasses a wide spectrum of clinical symptoms. The perinatal lethal form is very rare and is considered a distinct form of classic type 2 Gaucher disease. Prominent features of the severe perinatal form are hepatosplenomegaly variable, associated with hydrops fetalis and ichthyosis. Here, we describe a child who presented generalized ichthyosis and died at 25 days of age. Genotype analysis revealed compound heterozygosity for the complex allele [L444P;E326K] and mutation P182L, described for the first time in this patient. Mutations E326K and L444P were on the same chromosome. Expression studies of mutant glucocerebrosidases showed that the double mutant allele had lower activity, 8.5% of wild type, in contrast to the activity of individual E326K and L444P mutant enzymes, 42.7% and 14.1%, respectively. The P182L mutant enzyme showed no glucocerebrosidase activity. A revision of the genotypes identified in a series of Spanish patients with type 2 Gaucher disease showed that the complex allele [L444P;E326K] accounted for 19.2% of patient alleles and that homozygosity for this allele or its heterozygosity with mutation L444P, or another severe mutation such as P182L, was associated with the perinatal lethal presentation of the disease. In contrast, the [L444P;E326K] allele was not detected in patients with classic type 2 diagnosed when several months old. The high frequency of the E326K substitution observed in patients with type 2 as compared to the general population (0.5%) suggests that this change may have a modulating negative effect on the clinical condition of these Gaucher disease patients when present in combination with mutation L444P. The relatively high prevalence of the double mutant allele in Spanish patients prompted us to perform a haplotype analysis, using four polymorphic markers, which suggest a common origin for this allele. During the mutational analysis of the series of type 2 patients, a novel mutation, I260T (c.896T>C), was identified.

Perinatal lethal Gaucher disease: a distinct phenotype along the neuronopathic continuum

Gaucher disease, the inherited deficiency of glucocerebrosidase, is characterized by significant genetic and phenotypic heterogeneity. At the extreme end of the phenotypic continuum is the perinatal lethal variant, typically presenting in utero or during the neonatal period as hydrops and/orcongenital ichthyosis, with severe and progressive neurological involvement. Insights from the null-allele Gaucher mouse model contributed to the identification of this distinct phenotype, which has unique epidermal involvement. While multiple mutations are encountered, many affected infants are homozygous for recombinant alleles. The diagnosis is often missed due to the early lethality and the failure to recognize the association between lysosomal disorders and hydrops fetalis. The incidence of severe perinatal Gaucher disease may prove more common than currently appreciated with greater physician awareness of the disorder.

Viable mouse models of acid beta-glucosidase deficiency: the defect in Gaucher disease

Gaucher disease is an autosomal recessively inherited disease caused by mutations at the acid beta-glucosidase (GCase) locus (GBA). To develop viable models of Gaucher disease, point mutations (pmuts), encoding N370S, V394L, D409H, or D409V were introduced into the mouse GCase (gba) locus. DNA sequencing verified each unique pmut. Mutant GCase mRNAs were near wild-type (WT) levels. GCase activities were reduced to 2 to 25% of WT in liver, lung, spleen, and cultured fibroblasts from pmut/pmut or pmut/null mice. The corresponding brain GCase activities were approximately 25% of WT. N370S homozygosity was lethal in the neonatal period. For the other pmut mice, a few storage cells appeared in the spleen at > or =7 months (D409H or D409V homozygotes) or > or =1 year (V394L homozygotes). V394L/null, D409H/null, or D409V/null mice showed scattered storage cells in spleen at approximately 3 to 4 months. Occasional storage cells (sinusoidal cells) were present in liver. In D409V/null mice, large numbers of Mac-3-positive storage cells (ie, macrophages) accumulated in the lung. Glycosphingolipid analyses showed varying rates of progressive glucosylceramide accumulation in visceral organs of pmut/pmut or pmut/null mice, but not in brain. These GCase-deficient mice provide tools for gaining insight into the pathophysiology of Gaucher disease and developing improved therapies.

Perinatal-lethal Gaucher disease

Gaucher disease is a lysosomal storage disease caused by glucocerebrosidase deficiency. Although purely visceral in most cases, some Gaucher disease patients have neurological signs. Signs of Gaucher disease appear after a symptom-free period, except in rare cases with fetal onset. The description of such cases was based mainly on single reports and siblings. We report here a series of perinatal-lethal Gaucher disease cases highlighting the specificity of this phenotype. We retrospectively studied eight original cases of proven Gaucher disease with fetal onset. Non-immune hydrops fetalis was present in all cases but one, and associated with hepatosplenomegaly, ichthyosis, arthrogryposis, and facial dysmorphy. The similarities between our cases and 33 previously described cases allow us to better delineate the perinatal-lethal Gaucher disease phenotype. Hydrops fetalis, in utero fetal death and neonatal distress are prominent features. When hydrops is absent, neurological involvement begins in the first week and leads to death within three months. Hepatosplenomegaly is a major sign, and associated with ichthyosis, arthrogryposis, and facial dysmorphy in some 35-43% of cases. Perinatal-lethal Gaucher disease is a specific entity defined by its particular course and signs that are absent in classical type 2 Gaucher disease. Our study provides clues to the diagnosis of this likely underdiagnosed condition, which must be biochemically confirmed in order to propose appropriate genetic counselling.

Intrauterine fetal death due to Farber disease: case report

We report a case of Farber disease in a fetus who died in utero at a gestational age of 29 weeks. Macroscopic examination showed moderate postmortem changes in a microcephalic female fetus (46,XX) with mild internal hydrops, two vessels in the umbilical cord, and a moderately enlarged, relatively well-preserved spleen. Microscopic examination showed foamy cells in the spleen. Electron microscopic examination revealed the presence of Farber bodies within these foamy cells. Enzyme studies of the fetus were not possible because all tissues were formalin fixed. Lipids were extracted from formalin-fixed tissues and increased levels of ceramide and the presence of hydroxyceramide in tissue of the spleen, liver, and lung were found. Glucosylceramide was not increased excluding saposin-precursor-deficiency. Because of these findings, both parents were tested for acid ceramidase activity in their leukocytes. They both had markedly reduced enzyme activity consistent with heterozygosity for Farber disease. To the best of our knowledge, this is the first published case of Farber disease in Dutch nonconsanguineous parents.

A new gene-pseudogene fusion allele due to a recombination in intron 2 of the glucocerebrosidase gene causes Gaucher disease

Gaucher disease is the most prevalent sphingolipid storage disorder in humans caused by a recessively inherited deficiency of the enzyme glucocerebrosidase. More than 100 mutations have been described in the glucocerebrosidase gene causing Gaucher disease. Some of them are complex alleles with several mutations due to recombination events between the gene and its highly homologous pseudogene. The generation of these recombinant alleles involves, in most cases, a crossover in the 3' end of the gene, beyond exon 8. However, in a few cases recombination took place in a more upstream location. Here we describe the analysis of a patient with type I Gaucher disease who bears a new complex allele. This allele was originated by a crossover between the gene and the pseudogene at intron 2, the most upstream recombination site described so far, which gave rise to a fusion gene. The patient was first diagnosed as homozygous for the c.1226 A --> G (N370S) mutation but the early onset of the disease prompted us to perform parental DNA analysis which showed that the mother was not a N370S carrier, suggesting deletion of at least part of the gene. Molecular analysis of the complex allele was carried out by Southern blot, PCR, and sequencing. We were able to close down the region of the recombination event to an interval of 18 nucleotides, corresponding to the last 15 nucleotides of intron 2 and the first 3 nucleotides of exon 3 of the gene. These 18 nucleotides are identical between the gene and pseudogene making any further refinement impossible. An exhaustive list of published glucocerebrosidase complex alleles, describing their recombination points, is included for comparison.

Identification of Gaucher cells in the chorionic villi associated with recurrent hydrops fetalis

Recurrent non-immune hydrops fetalis has rarely been reported. In order to detect the risk of recurrence in a subsequent pregnancy, one should carefully consider the possibility of an inborn error of metabolism. In such cases, placental examination may be useful in detecting such metabolic storage disorders in the fetus, which usually present as vacuolization of placental cells. We describe a rare case of recurrent hydrops that was detected by placental examination. Through light microscopy, electron microscope (EM) studies and beta-glucocerebrosidase activity the disease was identified as Gaucher's disease.

Prenatal diagnosis of Gaucher's disease type 2. Ultrasonographic, biochemical and histological aspects

We report on the early prenatal diagnosis of fetal Gaucher disease type 2 by ultrasound examination and beta-glucosidase activity assay on amniocytes from a fetus of 15 weeks' gestation whose first sibling fetus had previously been affected with hydrops fetalis. These cases emphasize the importance of the pathological examination of all fetuses presenting with hydrops fetalis and also stress that minimal and precocious echographic signs can be suggestive of such a lysosomal storage disease.

Type 2 Gaucher disease: the collodion baby phenotype revisited

The association of Gaucher disease, the inherited deficiency of lysosomal glucocerebrosidase (EC 3.2.1.45), and congenital ichthyosis was first noted a decade ago. Subsequently, a null allele type 2 Gaucher mouse was generated that also exhibited ichthyotic skin, confirming that the skin disorder and enzyme deficiency were directly related. This paper details the clinical and molecular characterisation of 6 cases of type 2 Gaucher disease presenting with the collodion baby phenotype. The identified mutant glucocerebrosidase alleles include two novel mutations (S196P and R131L) and two rare point mutations (R120W and R257Q), as well as alleles resulting from recombination with the nearby glucocerebrosidase pseudogene. There is significant genotypic heterogeneity in this rare subset of patients with type 2 Gaucher disease. Gaucher disease should be considered in the differential diagnosis of congenital ichthyosis in the newborn period.

Glucocerebrosidase gene mutations in patients with type 2 Gaucher disease

Gaucher disease, the most common lysosomal storage disorder, results from the inherited deficiency of the enzyme glucocerebrosidase. Three clinical types are recognized: type 1, non-neuronopathic; type 2, acute neuronopathic; and type 3, subacute neuronopathic. Type 2 Gaucher disease, the rarest type, is progressive and fatal. We have performed molecular analyses of a cohort of 31 patients with type 2 Gaucher disease. The cases studied included fetuses presenting prenatally with hydrops fetalis, infants with the collodion baby phenotype, and infants diagnosed after several months of life. All 62 mutant glucocerebrosidase (GBA) alleles were identified. Thirty-three different mutant alleles were found, including point mutations, splice junction mutations, deletions, fusion alleles and recombinant alleles. Eleven novel mutations were identified in these patients: R131L, H255Q, R285H, S196P, H311R, c.330delA, V398F, F259L, c.533delC, Y304C and A190E. Mutation L444P was found on 25 patient alleles. Southern blots and direct sequencing demonstrated that mutation L444P occurred alone on 9 alleles, with E326K on one allele and as part of a recombinant allele on 15 alleles. There were no homozygotes for point mutation L444P. The recombinant alleles that included L444P resulted from either reciprocal recombination or gene conversion with the nearby glucocerebrosidase pseudogene, and seven different sites of recombination were identified. Homozygosity for a recombinant allele was associated with early lethality. We have also summarized the literature describing mutations associated with type 2 disease, and list 50 different mutations. This report constitutes the most comprehensive molecular study to date of type 2 Gaucher disease, and it demonstrates that there is significant phenotypic and genotypic heterogeneity among patients with type 2 Gaucher disease. Hum Mutat 15:181-188, 2000. Published 2000 Wiley-Liss, Inc.

Non-pseudogene-derived complex acid beta-glucosidase mutations causing mild type 1 and severe type 2 gaucher disease

Gaucher disease is an autosomal recessive inborn error of glycosphingolipid metabolism caused by the deficient activity of the lysosomal hydrolase, acid beta-glucosidase. Three phenotypically distinct subtypes result from different acid beta-glucosidase mutations encoding enzymes with absent or low activity. A severe neonatal type 2 variant who presented with collodion skin, ichthyosis, and a rapid neurodegenerative course had two novel acid beta-glucosidase alleles: a complex, maternally derived allele, E326K+L444P, and a paternally inherited nonsense mutation, E233X. Because the only other non-pseudogene-derived complex allele, D140H+E326K, also had the E326K lesion and was reported in a mild type 1 patient with a D140H+E326K/K157Q genotype, these complex alleles and their individual mutations were expressed and characterized. Because the E233X mutation expressed no activity and the K157Q allele had approximately 1% normal specific activity based on cross-reacting immunologic material (CRIM SA) in the baculovirus system, the residual activity in both patients was primarily from their complex alleles. In the type 1 patient, the D140H+E326K allele was neuroprotective, encoding an enzyme with a catalytic efficiency similar to that of the N370S enzyme. In contrast, the E326K+L444P allele did not have sufficient activity to protect against the neurologic manifestations and, in combination with the inactive E233X lesion, resulted in the severe neonatal type 2 variant. Thus, characterization of these novel genotypes with non-pseudogene-derived complex mutations provided the pathogenic basis for their diverse phenotypes.

Genotypic heterogeneity and phenotypic variation among patients with type 2 Gaucher's disease

Gaucher's disease, the inherited deficiency of glucocerebrosidase, manifests with vast phenotypic variation. Even among patients with type 2 (acute neuronopathic) Gaucher's disease, there is a spectrum of clinical presentations. DNA samples from 14 patients with type 2 Gaucher's disease with a course ranging from intrauterine death at 22 wk of gestation to survival until age 30 mo were studied. L444P was the only common mutation identified, found in 15 patients' alleles. Sequencing of genomic DNA amplified by long template PCR revealed that mutation L444P occurred as a single point mutation in seven mutant alleles and as part of a recombinant allele in eight mutant alleles. Two patients had a deletion of 55 bp in exon 9; in one patient the deletion was part of a recombinant allele, and in a second the deletion occurred alone. Direct sequencing identified R120W on one allele, P415R on another, and one fetus was homoallelic for a deletion of a C nucleotide at codon 139 in exon 5. Eight of the mutant alleles remain unidentified. Northern blots revealed an appropriately sized mRNA in all except one of the patients studied. Of the 14 type 2 Gaucher patients, three had hydrops fetalis and died in utero or at birth, five had congenital ichthyosis, and seven survived 5 mo or more. Patients who died in the neonatal period had decreased protein detected by Western blot, regardless of genotype observed. These studies demonstrate that genotypic heterogeneity exists in patients with type 2 Gaucher's disease, even among infants with the most severe phenotypes.

Type 2 Gaucher disease with hydrops fetalis in an Ashkenazi Jewish family resulting from a novel recombinant allele and a rare splice junction mutation in the glucocerebrosidase locus

Gaucher disease, the deficiency of the lysosomal enzyme glucocerebrosidase (EC 3.2.1.45), is frequently encountered in the Ashkenazi Jewish population. Carrier screening for Gaucher disease by enzyme analysis performed during a routine pregnancy indicated that both Ashkenazi parents were carriers. Screening for four common Gaucher mutations was subsequently performed on fetal and parental DNA. None of the common Ashkenazi mutations were identified. However, when exons 9-11 were amplified and digested with NciI to detect the L444P mutation, it appeared that the mother and the fetus had an unusual allele and that the expected paternal allele was not present. When the fetal amniocytes were found to have less than 2% of the normal glucocerebrosidase activity and a fetal sonogram revealed hydrops fetalis, the pregnancy was terminated. The diagnosis of severe type 2 Gaucher disease was confirmed at autopsy. Ultrastructural studies of epidermis from the fetus revealed the characteristic disruption of lamellar bilayers, diagnostic for type 2 Gaucher disease. In subsequent studies of the fetal DNA, long-template polymerase chain reaction amplification revealed one appropriately sized band (approximately 6.5 kb) and one smaller (approximately 5.2 kb) band. Sequencing of the approximately 5.2-kb fragment identified a novel fusion allele resulting from recombination between the glucocerebrosidase gene and its pseudogene beginning in intron 3. This fusion allele was inherited from the father. The result was confirmed by Southern blot analysis using the enzyme S8tII. Sequencing of the 6.5-kb fragment identified a previously described, although rare, T-to-G splice junction mutation in intron 10 of the maternal allele, which introduced an NciI site. The couple had a subsequent pregnancy which was also found to be affected. This case study identifies a novel recombinant allele and an unusual splice junction mutation, and demonstrates that even in the Ashkenazi population, screening for common mutations may not accurately identify the most severe forms of the disease.

Mice with type 2 and 3 Gaucher disease point mutations generated by a single insertion mutagenesis procedure

Gaucher disease is caused by mutations in the gene encoding the lysosomal enzyme glucocerebrosidase (GC). Three clinical types of Gaucher disease have been defined according to the presence (type 2 and 3) or absence (type 1) of central nervous system disease and severity of clinical manifestations. The clinical course of the disease correlates with the mutation carried by the GC gene. To produce mice with point mutations that correspond to the clinical types of Gaucher disease, we have devised a highly efficient one-step mutagenesis method-the single insertion mutagenesis procedure (SIMP)-to introduce human disease mutations into the mouse GC gene. By using SIMP, mice were generated carrying either the very severe RecNciI mutation that can cause type 2 disease or the less severe L444P mutation associated with type 3 disease. Mice homozygous for the RecNciI mutation had little GC enzyme activity and accumulated glucosylceramide in brain and liver. In contrast, the mice homozygous for the L444P mutation had higher levels of GC activity and no detectable accumulation of glucosylceramide in brain and liver. Surprisingly, both point mutation mice died within 48 hr of birth, apparently of a compromised epidermal permeability barrier caused by defective glucosylceramide metabolism in the epidermis.

Gaucher's disease: the best laid schemes of mice and men

The creation of animal models of Gaucher's disease, the inherited deficiency of the enzyme glucocerebrosidase, has led to new clinical insights and to a new appreciation of the complexity of the glucocerebrosidase gene locus. Murine embryonic stem cells with targeted modifications in the glucocerebrosidase gene were used to generate mouse models of Gaucher's disease, the first having a null glucocerebrosidase allele. The resulting knockout mice have no glucocerebrosidase activity and die within 12 hours of birth. Ultrastructural studies of liver, spleen, brain and bone marrow demonstrate the characteristic storage material seen in Gaucher patients. In the nervous system, storage of lipid increased in a rostral-caudal distribution. Analysis of skin from the knockout mice revealed histological, ultrastructural and biochemical abnormalities. The null allele Gaucher mice are analogous to neonates with Type 2 Gaucher's disease who present with hydrops foetalis and/or congenital ichthyosis. Moreover, the epidermal changes seen in Type 2 mice are also found in Type 2 patients and may provide a means to presymptomatically discriminate Type 2 from Type 1 and 3 Gaucher's disease. Another targeted modification in the murine glucocerebrosidase gene locus led to the discovery of a contiguous gene, metaxin. Closer analysis of the glucocerebrosidase gene locus, including sequencing of 75 kb of genomic DNA, reveals that this is a gene-rich region coding for seven genes and two pseudogenes. Further study of these closely arrayed genes may contribute to our understanding of the clinical variation encountered among patients with Gaucher's disease.

Prenatal lethality of a homozygous null mutation in the human glucocerebrosidase gene

The complete spectrum of clinical phenotypes resulting from glucocerebrosidase deficiency continues to evolve. While most patients with Gaucher disease have residual glucocerebrosidase activity, we describe a fetus with severe prenatal lethal type 2 (acute neuronopathic) Gaucher disease lacking glucocerebrosidase activity. This 22-week fetus was the result of a first cousin marriage and had hydrops, external abnormalities, hepatosplenomegaly, and Gaucher cells in several organs. Fetal fibroblast DNA was screened for common Gaucher mutations, none of which was detected. Southern blot analysis using the restriction enzymes SstII and SspI ruled out a fusion gene, deletion, or duplication of either allele, and quantitative studies of SspI digested genomic DNA indicated that both alleles were present. Northern blot analysis of total RNA from fetal fibroblasts demonstrated no detectable transcription, although RT-PCR successfully amplified several exons, suggesting the presence of a very unstable mRNA. Direct PCR sequencing of all exons demonstrated a homozygous frameshift mutation (deletion of a C) on codon 139 in exon 5, thereby introducing a premature termination codon in exon 6. The absence of glucocerebrosidase protein was confirmed by Western analysis. This unique case confirms the essential role of glucocerebrosidase in human development and, like the null allele Gaucher mouse, demonstrates the lethality of a homozygous null mutation. The presence of this novel mutation and the resulting unstable mRNA accounts for the severity of the phenotype observed in this fetus, and contributes to the understanding of genotype/phenotype correlation in Gaucher disease.