Inheritance of the S113L mutation within an inbred family with carnitine palmitoyltransferase enzyme deficiency

Deficiency of carnitine palmitoyltransferase type II (CPT II) is a clinically heterogeneous autosomal recessive disorder of lipid metabolism. The most common mutation in the CPT 11 gene is the S113L mutation, which substitutes leucine for serine at amino acid position 113. We studied an inbred family with three affected cousins with CPT II deficiency and found the S113L mutation to be present in a homozygous state in all three patients. Pedigree analysis traced the S 113L mutation back to one common ancestor. Although the patients in this family have an identical genotype at the CPT II locus, their clinical picture ranges from asymptomatic to lethal.     

Carnitine palmitoyltransferases 1 and 2: biochemical, molecular and medical aspects

Carnitine palmitoyltransferase (CPT) deficiencies are common disorders of mitochondrial fatty acid oxidation. The CPT system is made up of two separate proteins located in the outer (CPT1) and inner (CPT2) mitochondrial membranes. While CPT2 is an ubiquitous protein, three tissue-specific CPT1 isoforms––the so-called “liver” (CPT1-A), “muscle” (CPT1B) and «brain» (CPT1-C) CPT1s––have been shown to exist. Amino acid and cDNA nucleotide sequences have been identified for all of these proteins. CPT1-A deficiency presents as recurrent attacks of fasting hypoketotic hypoglycemia. Twenty four CPT1A mutations have been reported to date. CPT1-B and -C deficiencies have not been hitherto identified. CPT2 deficiency has several clinical presentations. The “benign” adult form (more than 200 families reported) is characterized by episodes of rhabdomyolysis triggered by prolonged exercise. The prevalent S113L mutation is found in about 50% of mutant alleles. The infantile-type CPT2 presents as severe attacks of hypoketotic hypoglycemia, occasionally associated with cardiac damage commonly responsible for sudden death before 1 year of age. In addition to these symptoms, features of brain and kidney dysorganogenesis are frequently seen in the neonatal-onset CPT2 deficiency, almost always lethal during the first month of life. Around 40 CPT2 mutations (private missense or truncating mutations) have hitherto been detected. Treatment is based upon avoidance of fasting and/or exercise, a low fat diet enriched with medium chain triglycerides and carnitine. Prenatal diagnosis may be offered for pregnancies at a 1/4 risk of infantile/severe-type CPT2 deficiency.     

Nature and Recurrence of AVPR2 Mutations in X-linked Nephrogenic Diabetes Insipidus

X-linked nephrogenic diabetes insipidus (NDI) is a rare disease with defective renal and extrarenal arginine-vasopressin V₂ receptor responses due to mutations in the AVPR2 gene in Xq28. We analyzed 31 independent NDI families to determine the nature and recurrence of AVPR2 mutations. Twenty-one new putative disease-causing mutations were identified: 113delCT, 253del35, 255del9, 274insG, V88M, R106C, 402delCT, C112R, Y124X, S126F, W164S, S167L, 684delTA, 804insG, W284X, A285P, W293X, R337X, and three large deletions or gene rearrangements. Five other mutations—R113W, Y128S, R137H, R181C, and R202C—that previously had been reported in other families were detected. There was evidence for recurrent mutation for four mutations (R113W, R137H, S167L, and R337X). Eight de novo mutation events were detected (274insG, R106C, Y128S, 167L [twice], R202C, 684delTA, and R337X). The origins were maternal (one), grandmaternal (one), and grandpaternal (six). In the 31 NDI families and 6 families previously reported by us, there is evidence both for mutation hot spots for nucleotide substitutions and for small deletions and insertions. More than half (58%) of the nucleotide substitutions in 26 families could be a consequence of 5-methylcytosine deamination at a CpG dinucleotide. Most of the small deletions and insertions could be attributed to slipped mispairing during DNA replication.     

Molecular analysis of carnitine palmitoyltransferase II deficiency with hepatocardiomuscular expression.

Carnitine palmitoyltransferase (CPT) II deficiency, an inherited disorder of mitochondrial long-chain fatty-acid (LCFA) oxidation, results in two distinct clinical phenotypes, namely, an adult (muscular) form and an infantile (hepatocardiomuscular) form. The rationale of this phenotypic heterogeneity is poorly understood. The adult form of the disease is commonly ascribed to the Ser-113-Leu substitution in CPT II. Only few data are available regarding the molecular basis of the infantile form of the disease. We report herein a homozygous A-2399-C transversion predicting a Tyr-628-Ser substitution in a CPT II-deficient infant. In vitro expression of mutant cDNA in COS-1 cells demonstrated the responsibility of this mutation for the disease. Metabolic consequences of the SER-113-Leu and Tyr-628-Ser substitutions were studied in fibroblasts. The Tyr-628-Ser substitution (infantile form) resulted in a 10% CPT II residual activity, markedly impairing LCFA oxidation, whereas the Ser-113-Leu substitution (adult form) resulted in a 20% CPT II residual activity, with out consequence on LCFA oxidation. These data show that CPT II activity has to be reduced below a critical threshold in order for LCFA oxidation in fibroblasts to be impaired. The hypothesis that this critical threshold differs among tissues could provide a basis to explain phenotypic heterogeneity of CPT II deficiency.     

Carnitine palmitoyltransferase IA polymorphism P479L is common in Greenland Inuit and is associated with elevated plasma apolipoprotein A-I

Carnitine palmitoyltransferase IA, encoded by CPT1A, is a key regulator of fatty acid metabolism. Previously, a loss-of-function mutation, namely, c.1436 C→T (p.P479L), was reported in CPT1A in the homozygous state in Canadian aboriginal male with presumed CPT1A deficiency. To determine the population frequency of this variant, we determined CPT1A p.P479L genotypes in 1111 Greenland Inuit. Associations between genotype and variation in plasma total cholesterol, triglycerides, LDL, HDL, apolipoprotein (apo) B, and apoA-I was also investigated. We found the L479 allele occurs at a high frequency in this sample (0.73), while it was completely absent in 285 nonaboriginal samples. This suggests that the original proband''s symptoms were not likely due to the CPT1A p.P479L mutation because it is very common in Inuit and because symptoms suggesting CPT1A deficiency have not been reported in any carrier subsequently studied. However, CPT1A p.P479L was associated with elevated plasma HDL and apoA-I levels. The association with increased levels of HDL and apoA-I suggest that the polymorphism might protect against atherosclerosis.     

Distribution of a knockdown resistance mutation (L1014S) in Anopheles gambiae s.s. and Anopheles arabiensis in western and southern Kenya

In Kenya, insecticide-treated mosquito nets (ITNs) distributed to pregnant women and children under 5 years old through various programs have resulted in a significant reduction in malaria deaths. All of the World Health Organization-recommended insecticides for mosquito nets are pyrethroids, and vector mosquito resistance to these insecticides is one of the major obstacles to an effective malaria control program. Anopheles gambiae s.s. and Anopheles arabiensis are major malaria vectors that are widely distributed in Kenya. Two point mutations in the voltage-gated sodium channel (L1014F and L1014S) are associated with knockdown resistance (kdr) to DDT and pyrethroids in An. gambiae s.s. While the same point mutations have been reported to be rare in An. arabiensis, some evidence of metabolic resistance has been reported in this species. In order to determine the distribution of the point mutation L1014S in An. gambiae s.s. and An. arabiensis in southern and western Kenya, we collected larvae and screened for the mutation by DNA sequencing. We found high allelic and homozygous frequencies of the L1014S mutation in An. gambiae s.s. The L1014S mutation was also widely distributed in An. arabiensis, although the allelic frequency was lower than in An. gambiae s.s. The same intron sequence (length: 57 base) found in both species indicated that the mutation was introgressed by hybridization. The allelic frequency of L1014S was higher in both species in western regions, demonstrating the strong selection pressure imposed by long-lasting insecticide-treated nets (LLITN)/ITN on the An. gambiae s.s. and An. arabiensis populations in those areas. The present contribution of the L1014S mutation to pyrethroid resistance in An. arabiensis may be negligible. However, the homozygous frequency could increase with continuing selection pressure due to expanded LLITN coverage in the future.     

Two novel gene mutations (Glu174→Lys,Phe383→Tyr) causing the “hepatic” form of carnitine palmitoyltransferase II deficiency

Carnitine palmitoyltransferase II (CPT II) deficiency has two different clinical forms, one with “hepatic” and the other with “muscular” symptoms. We studied the molecular basis of the “hepatic” form in two Japanese siblings. Their CPT II activity in lymphoblasts was reduced to 3% of the level observed in normal controls. cDNA analysis showed that the proband was a compound heterozygote. One allele carried a new mutation, G621→A (Glu174→Lys). The other carried three single-base substitutions; a new mutation, T1249→A (Phe383→Tyr), and two previously reported polymorphisms. The brother had the same four substitutions. Neither of the two new mutations in this study was detected in the 60 alleles of 30 Japanese control subjects. Secondary structure prediction analysis of the mutated CPT II protein was different from that of the normal protein. We concluded that these mutations caused the “hepatic” form of CPT II deficiency in the probands. Received: 16 October 1995     

Determining the frequency of common mutations in the GBA gene in patients with Gaucher disease in Ukraine

A molecular-genetics investigation is conducted on 27 patients from 26 families. Common mutations in the GBA gene (N370S, L444P, and 84GG) are studied. The overall frequency of the common mutations is nearly 58%, with the percentage of alleles that carry the N370S mutation close to 42.3% and the proportion that carry the L444P mutation, 15.4%. No allele containing the 84GG mutation was found. Besides other mutations, the rare mutations P178S, W184R, and Rec Nci I (together with N370S) were also found in the GBA gene in patients with the nonneuronopathic form of the disease, along with the genotypes G377S/c 999GA and D409H/R 120W/G202R in patients with the chronic neuronopathic form. An analysis of the correlation between the genotype and the course of the disease in the patients showed that the genotype-phenotype correlations were close to that described for European populations.     

Identification of genetic mutations in Japanese patients with fructose-1,6-bisphosphatase deficiency.

Fructose-1,6-bisphosphatase (FBPase) deficiency is an autosomal recessive inherited disorder and may cause sudden unexpected infant death. We reported the first case of molecular diagnosis of FBPase deficiency, using cultured monocytes as a source for FBPase mRNA. In the present study, we confirmed the presence of the same genetic mutation in this patient by amplifying genomic DNA. Molecular analysis was also performed to diagnose another 12 Japanese patients with FBPase deficiency. Four mutations responsible for FBPase deficiency were identified in 10 patients from 8 unrelated families among a total of 13 patients from 11 unrelated families; no mutation was found in the remaining 3 patients from 3 unrelated families. The identified mutations included the mutation reported earlier, with an insertion of one G residue at base 961 in exon 7 (960/961insG) (10 alleles, including 2 alleles in the Japanese family from our previous report [46% of the 22 mutant alleles]), and three novel mutations--a G-->A transition at base 490 in exon 4 (G164S) (3 alleles [14%]), a C-->A transversion at base 530 in exon 4 (A177D) (1 allele [4%]), and a G-->T transversion at base 88 in exon 1 (E30X) (2 alleles [9%]). FBPase proteins with G164S or A177D mutations were enzymatically inactive when purified from E. coli. Another new mutation, a T-->C transition at base 974 in exon 7 (V325A), was found in the same allele with the G164S mutation in one family (one allele) but was not responsible for FBPase deficiency. Our results indicate that the insertion of one G residue at base 961 was associated with a preferential disease-causing alternation in 13 Japanese patients. Our results also indicate accurate carrier detection in eight families (73%) of 11 Japanese patients with FBPase deficiency, in whom mutations in both alleles were identified.     

Frequency of MEFV gene mutations in Hatay province,Mediterranean region of Turkey and report of a novel missense mutation (I247V)

In the present study, 1000 patients with clinical suspicion of FMF were retrospectively reviewed to determine the spectrum of MEFV gene mutations by using DNA sequence analysis between September, 2008 and April, 2012. Sixteen different mutations and 55 different genotypes were detected in 618 of 1000 patients. Among 16 different mutations, R202Q (21.35%) was the most frequently observed mutation; followed by E148Q (8.85%), M694V (7.95%), M680I (2.40%), V726A (1.85%), M694I (0.95%), A744S (0.80%), R761H (0.55%), P283L (0.35%), K695R (0.20%), E230K (0.15%), L110P (0.10%), I247V (0.05%), G196W (0.05%) and G304R (0.05%). In the present study, a novel missense mutation (I247V) and a silent variant (G150G) were identified in the MEFV gene. On the other hand, P238L, G632A and G304R mutations are the first cases reported from Turkey. Our results indicated that MEFV mutations are highly heterogeneous in our study population as in other regions of Turkey and mutation screening techniques such as PCR-RFLP, amplification refractory mutation system or reverse hybridization do not adequately detect uncommon or novel mutations. Therefore, it was proven that sequence analysis of the MEFV gene could be useful for detection of rare or unknown mutations.     

Ataxia with isolated vitamin E deficiency: heterogeneity of mutations and phenotypic variability in a large number of families.

Ataxia with vitamin E deficiency (AVED), or familial isolated vitamin E deficiency, is a rare autosomal recessive neurodegenerative disease characterized clinically by symptoms with often striking resemblance to those of Friedreich ataxia. We recently have demonstrated that AVED is caused by mutations in the gene for alpha-tocopherol transfer protein (alpha-TTP). We now have identified a total of 13 mutations in 27 families. Four mutations were found in >=2 independent families: 744delA, which is the major mutation in North Africa, and 513insTT, 486delT, and R134X, in families of European origin. Compilation of the clinical records of 43 patients with documented mutation in the alpha-TTP gene revealed differences from Friedreich ataxia: cardiomyopathy was found in only 19% of cases, whereas head titubation was found in 28% of cases and dystonia in an additional 13%. This study represents the largest group of patients and mutations reported for this often misdiagnosed disease and points to the need for an early differential diagnosis with Friedreich ataxia, in order to initiate therapeutic and prophylactic vitamin E supplementation before irreversible damage develops.     

Crohn disease: frequency and nature of CARD15 mutations in Ashkenazi and Sephardi/Oriental Jewish families

Crohn disease (CD), an inflammatory bowel disease, is a multifactorial trait with the highest frequency in Ashkenazi Jewish (AJ) individuals of Central European origin. Recently, three common predisposing CARD15 mutations (R702W, G908R, and 1007fs) and a polymorphism (P268S) were identified. To determine whether CARD15 mutations account for the higher prevalence of CD in AJ individuals, the haplotypes and allele frequencies of the common mutations and variants were assessed in 219 members of 50 AJ and 53 members of 10 Sephardi/Oriental Jewish (SOJ) multiplex families with CD, in 36 AJ patients with sporadic CD, and in 246 AJ and 82 SOJ controls. A higher frequency of CARD15 mutations was found in AJ patients from multiplex families with CD from Central (44.0%) versus Eastern (24.0%) Europe, especially for G908R and 1007fs, and in SOJ patients (34.5%) compared with AJ (10.1%) or SOJ (5.4%) controls. Contrary to expectation, the frequency of the common mutations was slightly lower in AJ patients with CD (30.1%) than in SOJ patients with CD (34.5%). The 702W allele was associated with both the P268 and 268S alleles. CARD15 mutation frequencies were greater in affected sib pairs than in sporadic CD cases but actually decreased in families with three or more affected sibs, raising the possibility of genetic heterogeneity. Similarly, our linkage evidence on chromosome 16 was diminished in the families with three or more affected sibs compared with sib pairs. Screening the CARD15 gene for rare variants revealed five novel changes (D113N, D357A, I363F, L550V, and N852S) of which N852S occurred only in AJ individuals and may be disease predisposing. Also, there was no evidence for increased risk associated with the recently described IVS(+158) single-nucleotide polymorphism. Although the AJ controls appear to have a higher frequency of CARD15 mutations than the SOJ controls, it is unlikely that this difference fully explains the excess frequency of CD in the AJ population.     

Novelty of Axin 2 and lack of Axin 1 gene mutation in colorectal cancer: a study in Kashmiri population

Colorectal cancer is (CRC) one of the leading causes of mortality and morbidity. Various genetic factors have been reported to be involved in the development of colorectal cancers including Axin gene. Axin, a major scaffold protein, plays an important role in various bio signaling pathways. We aim to study mutational pattern of Axin gene in colorectal cancer patients of Kashmiri population. The paired tumor and adjacent normal tissue specimens of 50 consecutive patients with CRC were used in our study. The DNA preparations were evaluated for the occurrence of Axin 1 and Axin 2 gene mutations by direct DNA sequencing. We analyzed exon 1a, 1b, 1c, 2, 4, 6, and 10 of Axin 1 and exon 7 of Axin 2. In this study, we found a novel mutation of G>T (GCT>TCT) transversion in exon 7 of Axin 2 gene at codon G695T (p.alanine >?serine) at a frequency of 6% (3/50). In the same exon of Axin 2 gene a single nucleotide polymorphism (SNP) was detected in codon L688L (CCT>CTT) at a frequency of 36% (18/50). In exon 1c of Axin 1 a SNP was detected at codon D726D (GAT>GAC) at a frequency of 62.5% (31/50). Both the SNPs were synonymous hence do not lead to change of amino acid. Although Axin 1 and Axin 2 gene mutations have been found to be involved in the development of colorectal cancers, it seems to be a relatively rare event in Kashmiri population. However, an interesting finding of this study is the novelty of Axin 2 gene mutations which may be a predisposing factor in ethnic Kashmiri population to CRC.     

Is screening for hereditary thrombophilia indicated in first early pregnancy loss?

OBJECTIVE: The aim of the study was to evaluate the importance of screening for thrombophilic mutations after the first early pregnancy loss. Setting: Thrombophilic mutations were examined in a sample of 100 women with at least one miscarriage. DNA was isolated from venous blood sample. We used methods of microarray, fragmentation analysis, High Resolution Melting and PCR-ARMS with following gel electrophoresis and visualisation. Chi-square test and in cases of low expected frequencies Yates correction were used to compare relative frequencies of individual mutations. The comparison of averages was performed by t-test. Results: We detected prevalence of factor V and II mutation of 9% and 3%, respectively. Single MTHFR mutation was found in 59% and double heterozygous MTHFR mutation in 23% of cases. No mutation was present in only 6% of the study group. Heterozygous mutations of factor V occurred 1.8 times more frequently in our study group compared to the general Czech women population. Also, the frequency of factor II mutation was 1.5-3 times higher. No carrier of these mutations had overt coagulation disorder, history of thromboembolic disease or that of habitual abortions. Conclusions: The frequency of thrombophilic mutations in the group of women with early pregnancy loss is 1.5-3 times higher than in the general population.     

Malony-CoA inhibits the S113L variant of carnitine-palmitoyltransferase II

Carnitine palmitoyltransferases (CPT), located both in the outer (CPT I) and inner membrane (CPT II) of mitochondria, are the key players for an efficient transport of long chain fatty acids into this cell compartment. The metabolite malonyl-CoA is known to inhibit CPT I, but not CPT II. His₆-N-hCPT2 (wild type) and His₆-N-hCPT2/S113L (variant) were produced recombinantly in prokaryotic host, purified and characterized according to their functional and regulatory properties. The wild type and the variant showed the same enzymatic activity and were both inhibited by malonyl-CoA and malonate in a time-dependent manner. The inhibition was, however, significantly more pronounced in the mutated enzyme. The residual activities were 40% and 5% at temperatures of 4 °C and 30 °C, respectively. The inhibitory effect proceeded irreversibly with no recovery after post-incubation of palmitoyl-CoA (Pal-CoA) as native substrate. A model of malonyl-CoA and malonate binding to human CPT II was suggested by docking studies to explain the action of the inhibitors regarding to the effect of the mutation on the protein conformation. Results indicated that not only CPT I, but also CPT II can be inhibited by malonyl-CoA. Thus, the complete inhibition of total CPT (i.e. CPT I and CPT II) in muscle homogenates by an established assay is not due to a lack of enzymatically active CPT II, but rather due to an abnormal regulation of the enzyme.     

<Emphasis Type="Italic">MEFV</Emphasis> mutations in patients with familial Mediterranean fever from the Aegean region of Turkey

Familial Mediterranean Fever (FMF) which is frequently present in Mediterranean populations is caused by mutations in the MEFV gene. According to recent data, MEFV mutations are not the only cause of FMF, but these are major genetic determinants which cause FMF. It has also been suggested that there may be a number of other genes causing FMF. The MEFV gene is located at 16p13.3 and encodes a protein, pyrin/marenostrin. More than 70 disease associated mutations and totally 186 mutations and polymorphisms have been defined in affected individuals. We have retrospectively evaluated the molecular test results of 1,201 patients identified as having FMF clinical symptoms referred to the Molecular Genetics Laboratory of the Department of Medical Genetics, Faculty of Medicine, Ege University, Izmir/Turkey over the last 4 years. Patients were tested for 12 common mutations in the MEFV gene using a strip assay method (Innogenetics, Belgium). Out of the 1,201 patients tested (2,402 chromosomes) in the Aegean region in Turkey, 654 (54.45%) did not carry any mutations, among the 547 (45.55%) patients with mutations 246 patients were either homozygous (101) or compound heterozygous (145), 296 carried only one detected mutation, and five patients had three mutations. Allelic frequencies for the four most common mutations in the mutation positive groups were 47.60% (M694V), 16.75% (E148Q), 12.95% (V726A), 11.94% (M680I G/C).The remaining alleles (10.76%) showed rare mutations which were R761H, P369S, A744S, K695R, F479L, M694I. When the frequencies of mutations detected in our group were compared to the frequencies reported in the other regions of Turkey, an increase in V726A mutation frequency was observed. No patient showed a I692del mutation which is sometimes evident in other Mediterranean populations.     

Steroid 21-hydroxylase (P450c21): a new allele and spread of mutations through the pseudogene

Lesions in the gene encoding the adrenal enzyme steroid 21-hydroxylase (P450c21) result in defective adrenal cortisol synthesis, often accompanied by aldosterone deficiency. The symptoms range from severe neonatal disease to inconspicuous symptoms in adulthood depending on the nature of the mutations. The 21-hydroxylase gene is present in close proximity to a highly homologous pseudogene, and both genes show variation in copy number between individuals. For complete DNA sequence characterization, we have applied selective polymerase chain reaction amplification and direct sequencing of all full-length steroid 21-hydroxylase genes present in individuals. Using healthy individuals with only one remaining steroid 21-hydroxylase allele as normal references, a new allele was found in two siblings, in whom clinical and laboratory findings demonstrated moderate enzyme deficiency. Full-length sequencing of this allele displayed an Arg 484 to Pro codon change in exon 10, in the same position as a previously identified GG to C mutation found in a patient with severe 21 -hydroxylase deficiency. Arg 484 is located within a stretch of amino acids that are highly conserved between mammalian 21-hydroxylases. The finding of the presently reported 21-hydroxylase allele indicates that the GG to C mutation from the severely affected patient has arisen by a two-step mechanism, consisting of a G to C transversion accompanied by an adjacent G deletion. When sequencing 26 pseudogenes, both these mutations, which are not present in the pseudogenes hitherto reported, were found at low frequency together with a number of other polymorphisms. Thus, also rare mutations can spread via the pseudogene and can therefore be expected to arise independently in unrelated individuals.     

Maple syrup urine disease: identification and carrier-frequency determination of a novel founder mutation in the Ashkenazi Jewish population

Maple syrup urine disease (MSUD) is a rare, autosomal recessive disorder of branched-chain amino acid metabolism. We noted that a large proportion (10 of 34) of families with MSUD that were followed in our clinic were of Ashkenazi Jewish (AJ) descent, leading us to search for a common mutation within this group. On the basis of genotyping data suggestive of a conserved haplotype at tightly linked markers on chromosome 6q14, the BCKDHB gene encoding the E1beta subunit was sequenced. Three novel mutations were identified in seven unrelated AJ patients with MSUD. The locations of the affected residues in the crystal structure of the E1beta subunit suggested possible mechanisms for the deleterious effects of these mutations. Large-scale population screening of AJ individuals for R183P, the mutation present in six of seven patients, revealed that the carrier frequency of the mutant allele was approximately 1/113; the patient not carrying R183P had a previously described homozygous mutation in the gene encoding the E2 subunit. These findings suggested that a limited number of mutations might underlie MSUD in the AJ population, potentially facilitating prenatal diagnosis and carrier detection of MSUD in this group.     

Gaucher disease: gene frequencies in the Ashkenazi Jewish population.

DNA from over 2,000 Ashkenazi Jewish subjects has been examined for the four most common Jewish Gaucher disease mutations, which collectively account for about 96% of the disease-producing alleles in Jewish patients. This population survey has made possible the estimation of gene frequencies for these alleles. Eighty-seven of 1,528 individuals were heterozygous for the 1226G (N370S) mutation, and four presumably well persons were homozygous for this mutation. The gene frequency for the 1226G allele was calculated to be .0311, and when these data were pooled with those obtained previously from another 593 Jewish subjects, a gene frequency of .032 with a standard error of .004 was found. Among 2,305 normal subjects, 10 were found to be heterozygous for the 84GG allele, giving a gene frequency of .00217 with a standard error of .00096. No examples of the IVS2(+1) mutation were found among 1,256 samples screened, and no 1448C (L444P) mutations were found among 1,528 samples examined. Examination of the distribution of Gaucher disease gene frequencies in the general population shows that the ratio of 1226G mutations to 84GG mutations is higher than that in the patient population. This is presumed to be due to the fact that homozygotes for the 1226G mutation often have late-onset disease or no significant clinical manifestations at all. To bring the gene frequency in the patient population into conformity with the gene frequency in the general population, nearly two-thirds of persons with a Gaucher disease genotype would be missing from the patient population, presumably because their clinical manifestations were very mild.