Stress-related genes and heroin addiction: a role for a functional FKBP5 haplotype.

BACKGROUND: Stress is a critical risk factor affecting both the development of and the relapse to drug addictions. Drug addictions are caused by genetic, environmental and drug-induced factors. The objective of this hypothesis-driven association study was to determine if genetic variants in stress-related genes are associated with heroin addiction. METHODS: 112 selected genetic variants in 26 stress-related genes were genotyped in 852 case subjects and 238 controls of predominantly European ancestry. The case subjects are former heroin addicts with a history of at least one year of daily multiple uses of heroin, treated at a methadone maintenance treatment program (MMTP). The two most promising SNPs were subsequently tested in an African-American sample comprising of 314 cases and 208 control individuals. RESULTS: Nineteen single nucleotide polymorphisms (SNPs) in 9 genes (AVP, AVPR1A, CRHR1, CRHR2, FKBP5, GAL, GLRA1, NPY1R and NR3C2) showed nominally significant association with heroin addiction. The associations of two FKBP5 SNPs that are part of one haplotype block, rs1360780 (intron 2) and rs3800373 (the 3' untranslated region), remained significant after correction for multiple testing (Pcorrected=0.03; OR=2.35, Pcorrected=0.0018; OR=2.85, respectively). The two SNPs also showed nominally significant association (P<0.05) with heroin addiction in an independent African-American cohort. FKBP5 is a co-chaperone that regulates glucocorticoid sensitivity. These FKBP5 SNPs were previously associated with diverse affective disorders and showed functional differences in gene expression and stress response. This study also supports our and others' previous reports of association of the GAL SNP rs694066 and the AVPR1A SNPs rs11174811, rs1587097 and rs10784339 with heroin and general drug addiction, respectively. CONCLUSIONS: This study suggests that variations in the FKBP5 gene contribute to the development of opiate addiction by modulating the stress response. These findings may enhance the understanding of the interaction between stress and heroin addiction.

Nerve growth factor ß polypeptide (NGFB) genetic variability: association with the methadone dose required for effective maintenance treatment.

Opioid addiction is a chronic disease with high genetic contribution and a large inter-individual variability in therapeutic response. The goal of this study was to identify pharmacodynamic factors that modulate methadone dose requirement. The neurotrophin family is involved in neural plasticity, learning, memory and behavior and deregulated neural plasticity may underlie the pathophysiology of drug addiction. Brain-derived neurotrophic factor (BDNF) was shown to affect the response to methadone maintenance treatment. This study explores the effects of polymorphisms in the nerve growth factor (ß polypeptide) gene, NGFB, on the methadone doses required for successful maintenance treatment for heroin addiction. Genotypes of 14 NGFB polymorphisms were analyzed for association with the stabilizing methadone dose in 72 former severe heroin addicts with no major co-medications. There was significant difference in methadone doses required by subjects with different genotypes of the NGFB intronic single-nucleotide polymorphism rs2239622 (P=0.0002). These results may have clinical importance.

Regional mRNA expression of the endogenous opioid and dopaminergic systems in brains of C57BL/6J and 129P3/J mice: strain and heroin effects.

We have previously shown strain and dose differences in heroin-induced behavior, reward and regional expression of somatostatin receptor mRNAs in C57BL/6J and 129P3/J mice. Using Real Time PCR we examined the effects of five doses of heroin on the levels of the transcripts of endogenous opioid peptides and their receptors and dopaminergic receptors in the mesocorticolimbic and nigrostriatal pathways in these same mice. Compared to C57BL/6J animals, 129P3/J mice had higher mRNA levels of Oprk1 in the nucleus accumbens and of Oprd1 in the nucleus accumbens and a region containing both the substantia nigra and ventral tegmental area (SN/VTA). In the cortex of 129P3/J mice, lower levels of both Oprk1 and Oprd1 mRNAs were observed. Pdyn mRNA was also lower in the caudate putamen of 129P3/J mice. Strain differences were not found in the levels of Oprm1, Penk or Pomc mRNAs in any region examined. Within strains, complex patterns of heroin dose-dependent changes in the levels of Oprm1, Oprk1 and Oprd1 mRNAs were observed in the SN/VTA. Additionally, Oprd1 mRNA was dose-dependently elevated in the hypothalamus. Also in the hypothalamus, we found higher levels of Drd1a mRNA in C57BL/6J mice than in 129P3/J animals and higher levels of DAT (Slc6a3) mRNA in the caudate putamen of C57BL/6J animals than in 129P3/J counterparts. Heroin had dose-related effects on Drd1a mRNA in the hypothalamus and on Drd2 mRNA in the caudate putamen.

Heroin addiction in African Americans: a hypothesis-driven association study.

Heroin addiction is a chronic complex disease with a substantial genetic contribution. This study was designed to identify gene variants associated with heroin addiction in African Americans. The emphasis was on genes involved in reward modulation, behavioral control, cognitive function, signal transduction and stress response. We have performed a case-control association analysis by screening with 1350 variants of 130 genes. The sample consisted of 202 former severe heroin addicts in methadone treatment and 167 healthy controls with no history of drug abuse. Single nucleotide polymorphism (SNP), haplotype and multi-SNP genotype pattern analyses were performed. Seventeen SNPs showed point-wise significant association with heroin addiction (nominal P< 0.01). These SNPs are from genes encoding several receptors: adrenergic (ADRA1A), arginine vasopressin (AVPR1A), cholinergic (CHRM2), dopamine (DRD1), GABA-A (GABRB3), glutamate (GRIN2A) and serotonin (HTR3A) as well as alcohol dehydrogenase (ADH7), glutamic acid decarboxylase (GAD1 and GAD2), the nucleoside transporter (SLC29A1) and diazepam-binding inhibitor (DBI). The most significant result of the analyses was obtained for the GRIN2A haplotype G-A-T (rs4587976-rs1071502-rs1366076) with protective effect (P(uncorrected) = 9.6E- 05, P(corrected) = 0.058). This study corroborates several reported associations with alcohol and drug addiction as well as other related disorders and extends the list of variants that may affect the development of heroin addiction. Further studies will be necessary to replicate these associations and to elucidate the roles of these variants in drug addiction vulnerability.

Bidirectional translational research: Progress in understanding addictive diseases.

The focus of this review is primarily on recent developments in bidirectional translational research on the addictions, within the Laboratory of the Biology of Addictive Diseases at The Rockefeller University. This review is subdivided into major interacting aspects, including (a) Investigation of neurobiological and molecular adaptations (e.g., in genes for the opioid receptors or endogenous neuropeptides) in response to cocaine or opiates, administered under laboratory conditions modeling chronic patterns of human self-exposure (e.g., chronic escalating "binge"). (b) The impact of such drug exposure on the hypothalamic-pituitary-adrenal (HPA) axis and interacting neuropeptidergic systems (e.g., opioid, orexin and vasopressin). (c) Molecular genetic association studies using candidate gene and whole genome approaches, to define particular systems involved in vulnerability to develop specific addictions, and response to pharmacotherapy. (d) Neuroendocrine challenge studies in normal volunteers and current addictive disease patients along with former addicts in treatment, to investigate differential pharmacodynamics and responsiveness of molecular targets, in particular those also investigated in the experimental and molecular genetic approaches as described above.

Genetic susceptibility to heroin addiction: a candidate gene association study.

Heroin addiction is a chronic complex disease with a substantial genetic contribution. This study was designed to identify genetic variants that are associated with susceptibility to develop heroin addiction by analyzing 1350 variants in 130 candidate genes. All subjects had Caucasian ancestry. The sample consisted of 412 former severe heroin addicts in methadone treatment, and 184 healthy controls with no history of drug abuse. Nine variants, in six genes, showed the lowest nominal P values in the association tests (P < 0.01). These variants were in noncoding regions of the genes encoding the mu (OPRM1; rs510769 and rs3778151), kappa (OPRK1; rs6473797) and delta (OPRD1; rs2236861, rs2236857 and rs3766951) opioid receptors; the neuropeptide galanin (GAL; rs694066); the serotonin receptor subtype 3B (HTR3B; rs3758987) and the casein kinase 1 isoform epsilon (CSNK1E; rs1534891). Several haplotypes and multilocus genotype patterns showed nominally significant associations (e.g. OPRM1; P = 0.0006 and CSNK1E; P = 0.0007). Analysis of a combined effect of OPRM1 and OPRD1 showed that rs510769 and rs2236861 increase the risk of heroin addiction (P = 0.0005). None of these associations remained significant after adjustment for multiple testing. This study suggests the involvement of several genes and variants in heroin addiction, which is worthy of future study.

Genotype patterns that contribute to increased risk for or protection from developing heroin addiction.

A genome-wide association study was conducted using microarray technology to identify genes that may be associated with the vulnerability to develop heroin addiction, using DNA from 104 individual former severe heroin addicts (meeting Federal criteria for methadone maintenance) and 101 individual control subjects, all Caucasian. Using separate analyses for autosomal and X chromosomal variants, we found that the strongest associations of allele frequency with heroin addiction were with the autosomal variants rs965972, located in the Unigene cluster Hs.147755 (experiment-wise q=0.053), and rs1986513 (q=0.187). The three variants exhibiting the strongest association with heroin addiction by genotype frequency were rs1714984, located in an intron of the gene for the transcription factor myocardin (P=0.000022), rs965972 (P=0.000080) and rs1867898 (P=0.000284). One genotype pattern (AG-TT-GG) was found to be significantly associated with developing heroin addiction (odds ratio (OR)=6.25) and explained 27% of the population attributable risk for heroin addiction in this cohort. Another genotype pattern (GG-CT-GG) of these variants was found to be significantly associated with protection from developing heroin addiction (OR=0.13), and lacking this genotype pattern explained 83% of the population attributable risk for developing heroin addiction. Evidence was found for involvement of five genes in heroin addiction, the genes coding for the mu opioid receptor, the metabotropic receptors mGluR6 and mGluR8, nuclear receptor NR4A2 and cryptochrome 1 (photolyase-like). This approach has identified several new genes potentially associated with heroin addiction and has confirmed the role of OPRM1 in this disease.

Somatic mosaicism in Fanconi anemia: evidence of genotypic reversion in lymphohematopoietic stem cells.

Somatic mosaicism has been observed previously in the lymphocyte population of patients with Fanconi anemia (FA). To identify the cellular origin of the genotypic reversion, we examined each lymphohematopoietic and stromal cell lineage in an FA patient with a 2815-2816ins19 mutation in FANCA and known lymphocyte somatic mosaicism. DNA extracted from individually plucked peripheral blood T cell colonies and marrow colony-forming unit granulocyte-macrophage and burst-forming unit erythroid cells revealed absence of the maternal FANCA exon 29 mutation in 74.0%, 80.3%, and 86.2% of colonies, respectively. These data, together with the absence of the FANCA exon 29 mutation in Epstein-Barr virus-transformed B cells and its presence in fibroblasts, indicate that genotypic reversion, most likely because of back mutation, originated in a lymphohematopoietic stem cell and not solely in a lymphocyte population. Contrary to a predicted increase in marrow cellularity resulting from reversion in a hematopoietic stem cell, pancytopenia was progressive. Additional evaluations revealed a partial deletion of 11q in 3 of 20 bone marrow metaphase cells. By using interphase fluorescence in situ hybridization with an MLL gene probe mapped to band 11q23 to identify colony-forming unit granulocyte-macrophage and burst-forming unit erythroid cells with the 11q deletion, the abnormal clone was exclusive to colonies with the FANCA exon 29 mutation. Thus, we demonstrate the spontaneous genotypic reversion in a lymphohematopoietic stem cell. The subsequent development of a clonal cytogenetic abnormality in nonrevertant cells suggests that ex vivo correction of hematopoietic stem cells by gene transfer may not be sufficient for providing life-long stable hematopoiesis in patients with FA.

Identification of Alu-mediated deletions in the Fanconi anemia gene FAA.

Fanconi anemia (FA) is an autosomal recessive syndrome associated with hypersensitivity to DNA cross-linking agents and predisposition to neoplasia. Eight complementation groups (A-H) have been described, but the only FA genes cloned so far are FAC and FAA. We have recently identified 40 different germline mutations, including microdeletions, microinsertions, and point mutations in genomic DNA from 97 FA patients from the International Fanconi Anemia Registry (IFAR) by single-strand conformational polymorphism (SSCP) analysis. Interestingly, only one mutant allele was identified in many of these patients. Haplotype analysis with intragenic polymorphisms, as well as cDNA analysis of some patients suggested the presence of large deletions that would not be detected by SSCP analysis. In this study, we report the occurrence of Alu-mediated genomic deletions in FAA. Two different deletions of 1.2 kb and 1.9 kb were found. Both deletions include exons 16 and 17 and remove a 156-bp segment from the transcript causing a shorter in-frame message. Sequence analysis revealed that introns 15 and 17 are rich in partial and complete Alu repeats. There are at least four head-to-tail arranged Alu elements in intron 17 and one in intron 15, all oriented in the 3'-->5' direction. Sequence analysis of the deletions showed that the 5' breakpoints occurred at different sites in the same Alu element in intron 15, while the 3' breakpoints were located in different Alu repeats in intron 17. Numerous Alu repeats are present in FAA, suggesting that Alu-mediated recombination might be an important mechanism for the generation of FAA mutations.

Sequence variation in the Fanconi anemia gene FAA.

Fanconi anemia (FA) is a genetically heterogeneous autosomal recessive syndrome associated with chromosomal instability, hypersensitivity to DNA crosslinking agents, and predisposition to malignancy. The gene for FA complementation group A (FAA) recently has been cloned. The cDNA is predicted to encode a polypeptide of 1,455 amino acids, with no homologies to any known protein that might suggest a function for FAA. We have used single-strand conformational polymorphism analysis to screen genomic DNA from a panel of 97 racially and ethnically diverse FA patients from the International Fanconi Anemia Registry for mutations in the FAA gene. A total of 85 variant bands were detected. Forty-five of the variants are probably benign polymorphisms, of which nine are common and can be used for various applications, including mapping studies for other genes in this region of chromosome 16q. Amplification refractory mutation system assays were developed to simplify their detection. Forty variants are likely to be pathogenic mutations. Seventeen of these are microdeletions/microinsertions associated with short direct repeats or homonucleotide tracts, a type of mutation thought to be generated by a mechanism of slipped-strand mispairing during DNA replication. A screening of 350 FA probands from the International Fanconi Anemia Registry for two of these deletions (1115-1118del and 3788-3790del) revealed that they are carried on about 2% and 5% of the FA alleles, respectively. 3788-3790del appears in a variety of ethnic groups and is found on at least two different haplotypes. We suggest that FAA is hypermutable, and that slipped-strand mispairing, a mutational mechanism recognized as important for the generation of germ-line and somatic mutations in a variety of cancer-related genes, including p53, APC, RB1, WT1, and BRCA1, may be a major mechanism for FAA mutagenesis.

The genomic organization of the Fanconi anemia group A (FAA) gene.

Fanconi anemia (FA) is a genetically heterogenous disease involving at least five genes on the basis of complementation analysis (FAA to FAE). The FAA gene has been recently isolated by two independent approaches, positional and functional cloning. In the present study we describe the genomic structure of the FAA gene. The gene contains 43 exons spanning approximately 80 kb as determined by the alignment of four cosmids and the fine localization of the first and the last exons in restriction fragments of these clones. Exons range from 34 to 188 bp. All but three of the splice sites were consistent with the ag-gt rule. We also describe three alternative splicing events in cDNA clones that result in the loss of exon 37, a 23-bp deletion at the 5' end of exon 41, and a GCAG insertion at the 3' portion also in exon 41. Sequence analysis of the 5' region upstream of the putative transcription start site showed no obvious TATA and CAAT boxes, but did show a GC-rich region, typical of housekeeping genes. Knowledge of the structure of the FAA gene will provide an invaluable resource for the discovery of mutations in the gene that accounts for about 60-66% of FA patients.

Molecular cloning and characterization of a full-length complementary DNA encoding human acid ceramidase. Identification Of the first molecular lesion causing Farber disease.

Human acid ceramidase ((AC) N-acylsphingosine amidohydrolase, EC 3.5. 1.23) hydrolyzes the sphingolipid ceramide into sphingosine and free fatty acid. Ceramide is an essential component of all sphingolipids and an important cell-signaling molecule. Moreover, an inherited deficiency of AC activity leads to the lysosomal storage disorder known as Farber disease. Human AC was purified from urine, and 117 amino acid residues were determined by microsequencing. Degenerative oligonucleotide probes were then constructed and used to screen for human fibroblast and pituitary cDNA libraries. Several partial cDNA clones were obtained, and two of these were combined to construct a full-length cDNA containing a 17-base pair (bp) 5'-untranslated sequence, a 1185-bp open reading frame encoding 395 amino acids, a 1110-bp 3'-untranslated sequence, and an 18-bp poly(A) tail. Transient expression of the full-length cDNA in COS-1 cells led to a 10-fold increase in AC activity. In addition, biosynthetic studies carried out in the transfected cells demonstrated that 13-kDa (alpha) and 40-kDa (beta) AC subunits were derived from a common 55-kDa precursor encoded by the full-length cDNA. This protein pattern was identical to that seen in normal human skin fibroblasts. A homoallelic point mutation (T222K) was also identified in the AC gene of a patient suffering from Farber disease, further confirming the authenticity of the full-length cDNA.

A locus for Fanconi anemia on 16q determined by homozygosity mapping.

We report the results of a genomewide scan using homozygosity mapping to identify genes causing Fanconi anemia, a genetically heterogeneous recessive disorder. By studying 23 inbred families, we detected linkage to a locus causing Fanconi anemia near marker D16S520 (16q24.3). Although -65% of our families displayed clear linkage to D16S520, we found strong evidence (P = .0013) of genetic heterogeneity. This result independently confirms the recent mapping of the FAA gene to chromosome 16 by Pronk et al. Family ascertainment was biased against a previously identified FAC gene on chromosome 9, and no linkage was observed to this locus. Simultaneous search analysis suggested several additional chromosomal regions that could account for a small fraction of Fanconi anemia in our families, but the sample size is insufficient to provide statistical significance. We also demonstrate the strong effect of marker allele frequencies on LOD scores obtained in homozygosity mapping and discuss ways to avoid false positives arising from this effect.

A molecular approach to the stratification of cardiovascular risk in families with Marfan's syndrome.

BACKGROUND: The fibrillin gene encodes a protein in the extracellular matrix, and this protein is widely distributed in elastic tissues. The fibrillin gene is the site of mutations causing Marfan's syndrome. This disorder shows a high degree of clinical variability both between and within families. Each family appears to have a unique mutation in the fibrillin gene, which precludes the routine use of mutation screening for presymptomatic diagnosis of the disorder. The goal of this study was to develop a widely applicable method of molecular diagnosis. METHODS: We used three newly characterized intragenic sites of normal DNA repeat-sequence variation (i.e., polymorphisms) as markers to follow the inheritance pattern of specific copies (alleles) of the fibrillin gene in multiple kindreds with various clinical features of Marfan's syndrome. RESULTS: The polymorphic markers allowed identification of the particular copy of the fibrillin gene that cosegregated with Marfan's syndrome in 13 of the 14 families tested. In 11 families a definite presymptomatic diagnosis of Marfan's syndrome could be made in family members who had only equivocal manifestations of the disorder. In two other families, some family members demonstrated either classic Marfan's syndrome or a milder but closely related phenotype. The copy of the fibrillin gene that cosegregated with classic Marfan's syndrome was not inherited by family members with the latter, atypical, form of the disease. These milder phenotypes, previously diagnosed as Marfan's syndrome, were not associated with aortic involvement. CONCLUSIONS: These results document the usefulness of novel polymorphic DNA repeat sequences in the presymptomatic diagnosis of Marfan's syndrome. Our findings also demonstrate that the various clinical phenotypes seen in selected families may be due not to single fibrillin mutations, but rather to different genetic alterations. These findings underscore the need for a modification of the current diagnostic criteria for Marfan's syndrome in order to achieve accurate risk assessment.

Identification and expression of a common missense mutation (L302P) in the acid sphingomyelinase gene of Ashkenazi Jewish type A Niemann-Pick disease patients.

Types A and B Niemann-Pick disease (NPD) result from the deficient activity of acid sphingomyelinase (ASM; E.C. 3.1.4.12) and the resultant lysosomal accumulation of sphingomyelin. Type A disease is a fatal, neurodegenerative disorder of infancy, whereas type B disease has no neurologic manifestations and is characterized primarily by reticuloendothelial involvement and survival into adulthood. Both disorders occur more frequently among individuals of Ashkenazi Jewish ancestry than in the general population. Recently, a missense mutation in the ASM gene (designated R496L) was detected in more than 30% of the ASM alleles from Ashkenazi Jewish type A NPD patients. We report a second, common mutation that resulted from a T to C transition at nucleotide 905 and predicted a leucine to proline substitution at ASM codon 302 (designated L302P). Notably, the L302P mutation occurred in 23.5% (8 of 34) of the Ashkenazi Jewish type A NPD alleles studied. In contrast, it was not found in any of the ASM alleles from non-Jewish type A patients, in 36 alleles from type B patients, or in 100 ASM alleles from normal Ashkenazi Jewish individuals. To confirm the authenticities of the L302P and R496L mutations, each nucleotide change was separately introduced into the full-length ASM cDNA by site-directed mutagenesis and transiently expressed in COS-1 cells. Neither mutation expressed ASM catalytic activity, consistent with the type A phenotype of homoallelic patients. The identification of the L302P mutation should further facilitate molecular carrier detection for NPD in the Ashkenazi Jewish population, particularly because the L302P mutation can be easily detected using the restriction enzyme, AlwNl.

Structural organization and complete nucleotide sequence of the gene encoding human acid sphingomyelinase (SMPD1).

Acid sphingomyelinase (ASM; HGMW-approved symbol, SMPD1) is the lysosomal phosphodiesterase that hydrolyzes sphingomyelin to ceramide and phosphocholine. The deficient activity of this enzyme results in Types A and B Niemann-Pick disease (NPD). The full-length cDNA encoding human ASM has been isolated and characterized (E. H. Schuchman, M. Suchi, T. Takahashi, K. Sandhoff, and R. J. Desnick (1991) J. Biol. Chem. 66:8531-8539), and the ASM gene has been localized to chromosomal region 11p15.1-p15.4 (L. V. Pereira, R. J. Desnick, D. Adler, C. M. Disteche, and E. H. Schuchman (1991) Genomics 9:229-234). Using the cDNA as a probe, a genomic clone containing the ASM genomic region was isolated and the complete nucleotide sequence of the human ASM gene, including 1116 and 468 nucleotides upstream and downstream from the ASM coding region, respectively, was determined. This housekeeping gene contained six exons ranging in size from 77 to 773 bp and five introns ranging in size from 153 to 1059 bp. Exon 2 was unusually large and encoded 258 amino acids, or about 44% of the mature ASM polypeptide. The alternatively spliced 172-bp type 1-specific sequence was encoded by exon 3, whereas the type 2-specific sequence was located at the 5' end of intron 2. An analysis of the intron/exon junctions revealed that there was a weak donor splice site (AAA gtgagg) at the exon 3/intron 3 junction which occasionally leads to alternative splicing of exon 3 and the occurrence of the type 2 and 3 ASM transcripts. A single Alu1 element in the reverse orientation was in intron 2, immediately downstream from the type 2-specific sequence.(ABSTRACT TRUNCATED AT 250 WORDS)

Niemann-Pick type B disease. Identification of a single codon deletion in the acid sphingomyelinase gene and genotype/phenotype correlations in type A and B patients.

Types A and B Niemann-Pick disease both result from the deficient activity of the lysosomal hydrolase, acid sphingomyelinase (E.C. 3.1.4.12). Type A Niemann-Pick disease is a severe neurodegenerative disorder of infancy which leads to death by three years of age, whereas Type B disease has a later age at onset, little or no neurologic involvement, and most patients survive into adulthood. To investigate the molecular basis for the remarkable phenotypic heterogeneity, the nature of the mutations causing Type B Niemann-Pick disease in Ashkenazi Jewish patients was determined. The entire acid sphingomyelinase coding region from an Ashkenazi Jewish Type B patient was polymerase chain reaction-amplified, subcloned, and completely sequenced. A three-base deletion was identified of nucleotides 1821-1823 in the cDNA which predicted the removal of an arginine residue from position 608 of the acid sphingomyelinase polypeptide (delta R608). The other cDNA clones from this patient had the R496L mutation previously identified in Type A Niemann-Pick disease patients. Both Ashkenazi Jewish Type B patients were heteroallelic for the delta R608 mutation, whereas this allele was not present in 15 unrelated non-Jewish Type B patients, with the notable exception of one mildly affected patient of Arabic descent who was homoallelic for the delta R608 mutation. These results indicate that the delta R608 mutation predicts the Type B Niemann-Pick disease phenotype, even in the presence of the R496L Type A allele, thereby providing the first genotype/phenotype correlation for this lysosomal storage disease. Although only two patients have been studied, it appears that the delta R608 mutation occurs frequently in Type B Niemann-Pick disease patients of Ashkenazi Jewish descent.