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Familial Mediterranean fever (FMF) is an autosomal recessive disorder characterized by recurrent attacks of fever and serositis, common in populations of Armenian, Arab, Sephardic Jewish and Turkish origin. Early diagnosis is crucial to start colchicine therapy that prevents the occurrence of attacks and renal amyloidosis. In the absence of functional test for FMF, the diagnosis remains clinical and is generally confirmed by molecular analysis of the MEFV gene. More than 40 missense mutations and two in-frame deletions have been reported, most of them being located in exon 10 of the gene. The M694V (c.2080A>G) mutation, the most frequent defect, is responsible for a severe phenotype when present in the homozygous state. The E148Q (c.442G>C) sequence variant, which is situated in exon 2, is also common, but its role in FMF is controversial. In order to assess the implication of the E148Q variation in FMF, we investigated 233 patients of Sephardic Jewish origin living in France and 213 disease-free relatives of these patients. The frequency of the E148Q allele was found to be similar in the two groups (3.62% and 3.75%, respectively, p=0.93). Most importantly, the frequency of the M694V/E148Q compound heterozygous genotype was comparable between the patients group (3.9%) and the healthy relatives group (4.2%, p=0.85). This population-based study, therefore, strongly supports the hypothesis that E148Q is a just a benign polymorphism and not a disease-causing mutation. Considering this variant as a mutation may lead to set false positive diagnoses and to neglect the likely existence of genetic heterogeneity in FMF., (Copyright 2003 Wiley-Liss, Inc.)

Objective: Familial Mediterranean fever (FMF) is an autosomal-recessive disorder that is common in Armenian, Turkish, Arab, and Sephardic Jewish populations. Its clinical diagnosis is one of exclusion, with the patients displaying nonspecific symptoms related to serosal inflammation. MEFV gene analysis has provided the first objective diagnostic criterion for FMF. However, in the absence of an identified mutation (NI/NI genotype), both the sensitivity of the molecular analyses and the involvement of the MEFV gene in FMF are called into question. The present study was designed to further evaluate the diagnostic value of MEFV analysis in another population of Mediterranean extraction., Methods: The MEFV gene was screened for mutations in 50 patients living in Karabakh (near Armenia) who fulfilled the established criteria for FMF. In addition, we analyzed published series of patients from the above-mentioned at-risk populations., Results: The mutation spectrum in Karabakhian patients, which consisted of only 6 mutations (with 26% of NI alleles), differed from that reported in Armenian patients. Strikingly, among patients from Karabakh and among all classically affected populations, the distribution of genotypes differed dramatically from Hardy-Weinberg equilibrium (P = 0.0016 and P < 0.00001, respectively). These results, combined with other population genetics-based data, revealed the existence of an FMF-like condition that, depending on the patients' ancestry, was shown to affect 85-99% of those with the NI/NI genotype., Conclusion: These data illuminate the meaning of negative results of MEFV analyses and show that in all populations evaluated, most patients with the NI/NI genotype had disease that mimicked FMF and was unrelated to the MEFV gene. Our findings also demonstrate the high sensitivity of a search for very few mutations in order to perform a molecular diagnosis of MEFV-related FMF.

In a patient with lethal factor VII (FVII) deficiency, 2 homozygous nucleotide substitutions were identified in the F7 gene: a IVS7+2T>G transversion involving the IVS7 donor splice site, followed by a mutation at nucleotide 10588 that would result in a missense variation (Arg224Gln). The mutated splice site, located within the first repeat of a minisatellite, is followed by a variable number of pseudo-sites, normally silent. To investigate the consequences of this mutation on F7 splicing, we designed normal and mutant minigenes, spanning exons 5 to 8. In cells transfected with the mutant construct, no normal splicing occurred. Only spliced transcripts including the first minisatellite repeat were observed, resulting from the activation of the most proximal wild-type pseudo-site, which would generate a truncated protein (stop codon upstream of nucleotide 10588). These findings, which suggest the existence of a mechanism selecting one single splice site among multiple cryptic sites, explain the patient's phenotype.

The growth hormone releasing hormone receptor (GHRHR) plays a critical role in growth. We identified three nominally unrelated kindreds harboring the identical mutation (E72X) in GHRHR, the gene that encodes GHRHR; all three families originated in the Indian subcontinent. Because of the relative geographic proximity of these populations, we employed haplotype analysis in the region of GHRHR to determine the likelihood that this mutation occurred in a common ancestor rather than having occurred on separate occasions in different individuals. Members of all three kindreds segregating the E72X mutation were genotyped for highly polymorphic dinucleotide repeat microsatellites in a 15.5 centimorgan (cM) region around GHRHR on chromosome 7p15. We conclude that the affected individuals share a common ancestor, and we use the association with linked markers to estimate the age of this unique mutation., (Copyright 2003 Wiley-Liss, Inc.)

Mutations in the GH receptor gene (GHR) cause congenital GH insensitivity, a genetic disorder characterized by severe growth retardation associated with high serum concentration of GH and low serum levels of IGF-I. Molecular defects have been identified in all GHR-coding exons, except exon 3, a sequence that encodes part of the extracellular domain of the receptor. In humans, GHR transcripts exist in two isoforms differing by the retention (GHRfl) or exclusion (GHRd3) of this particular exon. As shown recently, such a dimorphic expression pattern, of unknown significance, could result from a retrovirus-mediated deletion event involving exon 3. This model for the generation of those two isoforms, however, leaves open the possibility that GHRd3 transcripts also arise from GHRfl alleles through alternative splicing. Here we report the identification of the first mutation in exon 3 of the GHR (W16X) in a patient with GH insensitivity and who also carries another nonsense mutation in exon 4. Intrafamilial correlation analyses of genotypes (presence of normal or mutant GHRfl and/or GHRd3 alleles), GHR expression patterns, and phenotypes provided direct evidence against an alternative splicing of exon 3. In particular, this exon was retained into transcripts originating from the GHRfl-W16X allele in both the patient and his mother. These observations, given the normal phenotype of the heterozygous parents, revealed also that a single copy of either GHRfl or GHRd3 is sufficient for normal growth.

This review focuses on the general strategies currently used to decipher the molecular bases of combined pituitary hormone deficiency (CPHD) of genetic origin. By summarizing illustrative approaches that turned out to be successful for identifying an increasing number of genes involved in CPHD in the human, this article consider predictable obstacles specific to the investigation of these rare and heterogeneous conditions, while underlining the previously unsuspected roles of several of these genes during the development of extrapituitary structures.

Primary ciliary dyskinesia (PCD) is a heterogeneous congenital disorder characterized by bronchiectasis and chronic sinusitis, sometimes associated with situs inversus (i.e., Kartagener's syndrome) and male infertility. At the cell level, the disease phenotype includes various axonemal abnormalities of respiratory cilia and sperm flagella. We have previously isolated DNAI1, the first gene involved in these diseases in patients lacking outer dynein arms. In this study, designed to find additional genes for other axonemal defects, we report the isolation of a novel human gene, hPF20, which is orthologous to Chlamydomonas pf20. The hPF20 gene is expressed as two major transcripts: one is expressed in testis only, whereas the second is weakly expressed in many other tissues. As flagella of Chlamydomonas strains carrying pf20 mutations lack the axonemal central complexes, we tested the involvement of the hPF20 gene in the disease phenotype of five patients in whom cilia or flagella display abnormal central complexes. Five intragenic polymorphisms were identified and used to exclude hPF20 in two consanguineous patients, while no mutation was found in the remaining patients. However, given the genetic heterogeneity of PCD, we consider that this gene remains a good candidate to be investigated in patients with abnormal central complexes.

Unlabelled: Patients with pseudocholinesterase (BChE) variants may exhibit markedly prolonged paralysis after the administration of succinylcholine or mivacurium. We sought to evaluate to what extent molecular biology may contribute to the biological assessment of such patients. We conducted a prospective cohort study in patients referred to our center between 1995 and 1999 for prolonged neuromuscular blockade after mivacurium or succinylcholine. For each patient, phenotyping was performed with a conventional biochemical technique and molecular biology for the detection of the atypical mutation (A variant). Among the 36 patients referred, 31 had low BChE activity, 26 had received mivacurium (BChE activity, 2.1 U/mL; 0.3-4.3 U/mL), and 5 had received succinylcholine (BChE activity, 1.9 U/mL; 1.1-3.2 U/mL) (mean; extreme values). The mean clinical duration of paralysis was 90 min (40-140 min) after succinylcholine and 301 min (120-720 min) after mivacurium. Thirty-two patients had a BChE deficiency of genetic origin: 20 were homozygous (AA), 10 were heterozygous (UA) for the A variant, and 2 did not have the A mutation (UU). One heterozygous UA patient had normal BChE activity. Nine among the heterozygous UA and the two homozygous UU patients probably carried a not-screened variant. In most cases, biochemical diagnosis was sufficient to confirm the existence of constitutional deficiency; molecular biology improved the accuracy of diagnosis in 11 patients (30%) but had few or no clinical implications for the patient him- or herself., Implications: Systematic screening for the pseudocholinesterase atypical variant by biochemical and DNA analysis after a prolonged neuromuscular blocking effect of succinylcholine or mivacurium shows that molecular biology could improve the diagnosis in approximately one third of patients, but with few clinical implications, compared with biochemical testing.

Studies of genetically engineered flies and mice have revealed the role that orthologs of the human LIM homeobox LHX4 have in the control of motor-neuron-identity assignment and in pituitary development. Remarkably, these mouse strains, which bear a targeted modification of Lhx4 in the heterozygous state, are asymptomatic, whereas homozygous animals die shortly after birth. Nevertheless, we have isolated the human LHX4 gene, as well as the corresponding cDNA sequence, to test whether it could be involved in developmental defects of the human pituitary region. LHX4, which encodes a protein 99% identical to its murine counterpart, consists of six coding exons and spans >45 kb of the q25 region of chromosome 1. We report a family with an LHX4 germline splice-site mutation that results in a disease phenotype characterized by short stature and by pituitary and hindbrain (i.e., cerebellar) defects in combination with abnormalities of the sella turcica of the central skull base. This intronic mutation, which segregates in a dominant and fully penetrant manner over three generations, abolishes normal LHX4 splicing and activates two exonic cryptic splice sites, thereby predicting two different proteins deleted in their homeodomain sequence. These findings, which elucidate the molecular basis of a complex Mendelian disorder, reveal the fundamental pleiotropic role played by a single factor that tightly coordinates brain development and skull shaping during head morphogenesis.

Many different pathogenic mutations in the mitochondrial (mt) transfer RNA (tRNA) genes have been reported for patients with mitochondrial encephalomyopathy. Although some of them are recurrent, most have only been described once and appear to be restricted to one patient or to one family. The incidence of mt tRNA gene alterations is not known, even though the frequency of some recurrent mutations has been analysed both in patients and in the general population. In this study, we describe the results of stepwise screening for sequence variations in the mt tRNA genes of 166 patients selected according to several criteria. Extensive sequence analysis of the tRNA genes was performed using denaturing gradient gel electrophoresis. A total of 31 patients (19%) were found to harbour significant levels of a pathogenic mutation, thus confirming the importance of mt tRNA mutations in human pathology. Forty-three different sequence variations were found, illustrating the great diversity of the mtDNA sequence in humans. The functional assessment of all these sequence variations represented a difficult task; it was mostly based on indirect data, such as the phylogenetic conservation of modified nucleotides and the proportions of variant species in different tissues of the index case or in blood of maternal relatives. Direct demonstration of a correlation between the proportion of heteroplasmic sequence variations and the cytochrome c oxidase defect was performed at the single muscle-fibre level. Eleven heteroplasmic sequence variations were found, six of which are new mutations. One is a known Caucasian polymorphism but the other 10 are pathogenic. Two of them are the well-known pathogenic MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) (A3243G) and MERRF (myoclonic epilepsy with ragged-red fibres) (A8344G) point mutations. They were found in 23 patients. The eight other mutations were restricted to one patient. The pathogenic nature of these mutations was demonstrated directly for five of them and hypothesized from indirect arguments for the other three. Thirty-two homoplasmic sequence variations were found. Twenty-nine were considered to be polymorphisms, even though 15 of these were found for the first time in our patients and two others had been reported previously as pathogenic. The pathogenic nature of three homoplasmic variants remains questionable.

Seventy-nine unrelated Lebanese patients were tested for 15 mutations in the MEFV gene: A761H, A744S, V726A, K695R, M694V, M694I, M694del, M6801 (G --> C), M680I (G --> A) in exon 10, F479L in exon 5, P369S in exon 3, T267I, E167D and E148Q in exon 2, using PCR digestion, ARMS, DGGE and/or sequencing. Mutations were detected in patients belonging to all communities, most interestingly the Maronite, Greek orthodox, Greek catholic, Syriac and Chiite communities. The most frequent mutations are M694V and V726A (27% and 20% of the total alleles respectively). M694I, E148Q and M680I mutations account respectively for 9%, 8% and 5%. Each of the K695R, E167D and F479L mutations was observed once and all the remaining mutations were not encountered. Of the alleles 33% do not carry any of the studied mutations. The mutation spectra, clinical features and severity of the disease differed among the Lebanese communities. The genotype-phenotype analysis showed a significant association (P < 0.001) between amyloidosis and the presence of mutations at codon 694 in exon 10 (both M694V and M694I). None of the patients carrying other mutations developed amyloidosis.

The effects of emulsome nanosize range lipid particles containing amphotericin B (EAmB) were compared with the reference formulation containing deoxycholate (Fungizone; Bristol-Myers Squibb, Munich, Germany) and with the commercial amphotericin lipid complex preparation (AmBisome; Nexstar, San Dimas, CA, USA). The minimal inhibitory concentrations of Fungizone and EAmB were identical although killing of Candida albicans was delayed when EAmB was used. In a tissue culture model and in mice, the incorporation of AmB into emulsomes resulted in a considerable reduction of toxicity in comparison with Fungizone. For comparison of the in vivo effect of the preparations a mouse model of systemic infection with C. albicans was used. All preparations were able to reduce the fungal burden in the liver and kidneys in comparison with control animals treated with isotonic saline. AmBisome was more efficient in the reduction of the fungal burden of the liver than EAmB and Fungizone, even when applied in a similar dosage of 1 mg kg(-1). In the kidneys, EAmB and Fungizone was slightly more effective than AmBisome. Therefore, in our models, the incorporation of AmB into nanosize particles was able to reduce toxicity without loss of efficiency. EAmB may be considered a candidate preparation for the treatment of infections with C. albicans in humans.

Mutations in MEFV, a gene encoding a protein (marenostrin/pyrin) of unknown function, are associated with familial Mediterranean fever, a genetic condition characterized by febrile episodes of serosal inflammation. Based on its primary structure, this 781 residue protein is thought to function as a nuclear effector molecule. However, recent transient expression studies indicated a perinuclear cytoplasmic localization. Here, we describe the isolation and expression of a novel human MEFV isoform, MEFV-d2, generated by in-frame alternative splicing of exon 2. This transcript, expressed in leukocytes, predicts a 570 residue protein designated marenostrin-d2. To investigate differences in subcellular localization between the full-length protein (marenostrin-fl) and marenostrin-d2, while providing against the overexpression of transiently expressed proteins, we have generated CHO cell lines stably expressing these two isoforms fused to the green fluorescent protein. The localization pattern of marenostrin-d2 differs dramatically from that of marenostrin-fl. Marenostrin-fl is homogeneously distributed over the entire cytoplasm, whereas marenostrin-d2 concentrates into the nucleus. To map the critical domain(s) specifying these differences, deletion mutants have been generated. Deletion of the putative nuclear localization signals (NLS) does not alter the nuclear localization of marenostrin-d2 whereas, despite the lack of discernible NLS in the domain encoded by the exon 1-exon 3 splice junction, deletion of this domain indeed disrupts this localization. These data, which challenge the current domain organization model of marenostrin, strongly suggest that MEFV encodes a nuclear protein and raises the possibility that MEFV alternative splicing may control functions of wild-type and mutant marenostrin proteins by regulating their translocation to the nucleus.

Primary ciliary dyskinesia (PCD) is an autosomal recessive disease characterized by chronic sinusitis and bronchiectasis, and usually associated with hypofertility. Half of the patients present a situs inversus, defining the Kartagener's syndrome. This phenotype results from axonemal abnormalities of respiratory cilia and sperm flagella, i.e., mainly an absence of dynein arms. Recently, a candidate-gene approach, based on documented abnormalities of immotile strains of Chlamydomonas reinhardtii, allowed us to identify the first gene involved in PCD. Following the same strategy, we have characterized DNAI2, a human gene related to Chlamzydomonas IC69, and evaluated its possible involvement in a PCD population characterized by an absence of outer dynein arms. DNAI2, which is composed of 14 exons located at 17q25, is highly expressed in trachea and testis. No mutation was found in the DNAI2 coding sequence of the twelve patients investigated. However, ten intragenic polymorphic sites and an EcoRI RFLP have been identified, allowing the exclusion of DNAI2 in three consanguineous families.

Familial Mediterranean fever (FMF) is a recessively inherited disorder predisposing to renal amyloidosis and associated with mutations in MEFV, a gene encoding a protein of unknown function. Differences in clinical expression have been attributed to MEFV-allelic heterogeneity, with the M694V/M694V genotype associated with a high prevalence of renal amyloidosis. However, the variable risk for patients with identical MEFV mutations to develop this severe complication, prevented by lifelong administration of colchicine, strongly suggests a role for other genetic and/or environmental factors. To overcome the well-known difficulties in the identification of modifying genetic factors, we investigated a relatively homogeneous population sample consisting of 137 Armenian patients with FMF from 127 independent families living in Armenia. We selected the SAA1, SAA2, and APOE genes-encoding serum amyloid proteins and apolipoprotein E, respectively-as well as the patients' sex, as candidate modifiers for renal amyloidosis. A stepwise logistic-regression analysis showed that the SAA1alpha/alpha genotype was associated with a sevenfold increased risk for renal amyloidosis, compared with other SAA1 genotypes (odds ratio [OR] 6. 9; 95% confidence interval [CI] 2.5-19.0). This association, which was present whatever the MEFV genotype, was extremely marked in patients homozygous for M694V (11/11). The risk for male patients of developing renal amyloidosis was fourfold higher than that for female patients (OR=4.0; 95% CI=1.5-10.8). This association, particularly marked in patients who were not homozygous for M694V (34.0% vs. 11.6%), was independent of SAA1-allelic variations. Polymorphisms in the SAA2 or APOE gene did not appear to influence susceptibility to renal amyloidosis. Overall, these data, which provide new insights into the pathophysiology of FMF, demonstrate that susceptibility to renal amyloidosis in this Mendelian disorder is influenced by at least two MEFV-independent factors of genetic origin-SAA1 and sex-that act independently of each other.

We studied the NF1 gene in 93 unrelated patients with neurofibromatosis type1, focusing the analysis on four exons that contain the highest number of possible mutations occurring at CpG sites. We used denaturing gradient gel electrophoresis to analyse exons 16, 28, 29 and 49, which contain 45 (25%) of the 183 possible mutations that could occur at the 120 CpG dinucleotides of the coding sequence. Six different mutations were identified, five of which are novel: two truncating mutations, W1810X and 5448insG, located in exon29; two splice defects leading to exon29 skipping, 5206-2A>G and 5546G>A; and one missense mutation, L844F, located in exon16. The already described R1748X mutation located in exon29 was found in two unrelated patients. The 5546G>A and R1748X mutations are located at CpG sites, whereas the W1810X involves a CpNpG site. Four novel polymorphisms, which may be helpful for family studies, were also identified. Overall, all but one mutations were found in exon29, a result which suggests that all the CpG sites of the NF1 coding sequence do not have the same mutability, and that exon29, the most CpG-rich exon, contains mutational hotspots associated with NF1., (Copyright 2000 Wiley-Liss, Inc.)

In humans, growth hormone receptor (GHR) transcripts exist in two isoforms differing by the retention (GHRfl) or exclusion (GHRd3) of exon 3, whereas in mice GHRfl is solely expressed. This species-specific expression pattern is believed to result from an alternative splice event that, on the basis of conflicting data obtained in humans, has been considered to be tissue-, developmentally, and/or individual-specific. To decipher the molecular basis of this unusual trait, we isolated a 6.8-kilobase fragment spanning exon 3 from individuals expressing GHRfl. Sequence analysis revealed the existence of two 99% identical retroelements flanking this exon. Unexpectedly, individuals expressing GHRd3 displayed a 2.7-kilobase deletion involving exon 3, which most likely results from an ancestral homologous recombination between the two retroelements. The lineage of these retroelements during primate evolution revealed the species specificity of the GHRd3 allele. These findings led us to propose a model underlying the existence of the sole GHRfl allele in most species. Such a retrovirus-mediated alternative splice mimicry, which clears up several as yet unexplained phenomena (i.e. the above-mentioned expression data, the Mendelian inheritance of GHR expression patterns, and the deletion of nonconsecutive exons in growth hormone resistant patients), represents a novel physiological mechanism accounting for protein diversity between and within species.

Familial Mediterranean fever (FMF) is an autosomal recessively inherited disease affecting patients of the Mediterranean basin. FMF is characterized by recurrent episodes of fever accompanied with topical signs of inflammation. Some patients can develop a renal amyloidosis associated (AA) amyloidosis. The administration of colchicine is an effective preventive treatment of both the attacks and amyloidosis. The FMF gene (MEFV) was cloned and missense mutations were found to be responsible for the disease. We investigated a large series of 303 unselected and unrelated patients of various ethnic backgrounds with a clinical suspicion of FMF to confirm or invalidate the diagnosis of FMF and to determine the spectrum of MEFV mutations. Molecular analysis focused on all the most frequent mutations identified so far, and an exhaustive analysis of exon 10, containing the mutational hotspot, was performed through DNA sequencing. Sixty-two percent of Sephardic, North African Arabs, Armenian and Turkish patients were either homozygous or compound heterozygous for MEFV mutations. In other populations surrounding the Mediterranean Sea such as Greek, Italian, Portuguese, Kurdish and Lebanese populations, mutations were also found. In general, patients without Mediterranean origin had no mutations in the MEFV gene. Two new mis-sense mutations were identified in exon 10 of the MEFV gene: the S675N in an Italian patient and the M680L in a French patient without any known at-risk ethnic ancestry.

Combined pituitary hormone deficiency (CPHD) has been linked with rare abnormalities in genes encoding transcription factors necessary for pituitary development. We have isolated LHX3, a gene involved in a new syndrome, using a candidate-gene approach developed on the basis of documented pituitary abnormalities of a recessive lethal mutation in mice generated by targeted disruption of Lhx3 (ref. 2). LHX3, encoding a member of the LIM class of homeodomain proteins, consists of at least six exons located at 9q34. We identified a homozygous LHX3 defect in patients of two unrelated consanguineous families displaying a complete deficit in all but one (adrenocorticotropin) anterior pituitary hormone and a rigid cervical spine leading to limited head rotation. Two of these patients also displayed a severe pituitary hypoplasia, whereas one patient presented secondarily with an enlarged anterior pituitary. These LHX3 mutations consist of a missense mutation (Y116C) in the LIM2 domain at a phylogenetically conserved residue and an intragenic deletion predicting a severely truncated protein lacking the entire homeodomain. These data are consistent with function of LHX3 in the proper development of all anterior pituitary cell types, except corticotropes, and extrapituitary structures.

The diagnosis of familial Mediterranean fever (FMF) has until recently been based on clinical signs alone. Discovery of the MEFV gene has enabled a molecular approach to diagnosis, which is already well established for diagnosing typical clinical forms of FMF. We evaluated the utility of this molecular approach in a large series of patients with various clinical presentations and ethnic origins. We looked for mutations in the MEFV gene in 303 unselected consecutive patients with a variable (from high to low) clinical suspicion of FMF. Two mutations were found in 133 patients (44%). In 22 patients (7%), the clinical diagnosis of FMF was unlikely according to the Tel Hashomer clinical criteria. Our results suggest that the spectrum of FMF-associated signs is broader than previously believed. Wider indications for genotyping should lead to more frequent diagnosis of FMF.

Background/aims: Liver iron accumulation has been described in patients with chronic active hepatitis (CAH) C, and could play a role in the course of liver disease and negatively influence the response to interferon. The aim of this study was to determine the prevalence and severity of liver iron accumulation in CAH C, to assess its relationship with the HFE C282Y and H63D mutations, and to study its interactions with hepatic histological lesions., Methods: Two hundred and nine patients (131 men, 78 women, mean age 44.3+/-12.0 years) with CAH C, including 19 patients with cirrhosis (9.1%) were studied. A semiquantitative grading system from 0 to 3 was used for histological assessment of liver iron accumulation on Perls' staining. The HFE C282Y and H63D mutations were screened for by restriction enzyme analysis performed on PCR-amplified products. Histological scores of activity and fibrosis were determined according to a previously validated METAVIR score system., Results: Liver iron accumulation was found in 88/209 patients (42.1%), and was generally mild. The C282Y and H63D allele frequencies were in 23 (11.0%), and 50 (23.9%), respectively. No association was found between the presence of liver iron accumulation and the detection of the C282Y and H63D mutations. A significant relationship was found between the severity of histological activity and liver iron accumulation of macrophagic or mixed (i.e. both macrophagic and hepatocytic) type (p = 0.04). Although the number of cirrhotic patients was small, cirrhosis was more frequently observed in patients with than without liver iron accumulation (17.2% vs. 3.3%, p = 0.004)., Conclusions: Overall, these data suggest that the liver iron accumulation in patients with CAH C is significantly associated with histological activity and cirrhosis, whereas the two missense hemochromatosis gene mutations are not major determinants.

Primary ciliary dyskinesia (PCD) is a group of heterogeneous disorders of unknown origin, usually inherited as an autosomal recessive trait. Its phenotype is characterized by axonemal abnormalities of respiratory cilia and sperm tails leading to bronchiectasis and sinusitis, which are sometimes associated with situs inversus (Kartagener syndrome) and male sterility. The main ciliary defect in PCD is an absence of dynein arms. We have isolated the first gene involved in PCD, using a candidate-gene approach developed on the basis of documented abnormalities of immotile strains of Chlamydomonas reinhardtii, which carry axonemal ultrastructural defects reminiscent of PCD. Taking advantage of the evolutionary conservation of genes encoding axonemal proteins, we have isolated a human sequence (DNAI1) related to IC78, a C. reinhardtii gene encoding a dynein intermediate chain in which mutations are associated with the absence of outer dynein arms. DNAI1 is highly expressed in trachea and testis and is composed of 20 exons located at 9p13-p21. Two loss-of-function mutations of DNAI1 have been identified in a patient with PCD characterized by immotile respiratory cilia lacking outer dynein arms. In addition, we excluded linkage between this gene and similar PCD phenotypes in five other affected families, providing a clear demonstration of locus heterogeneity. These data reveal the critical role of DNAI1 in the development of human axonemal structures and open up new means for identification of additional genes involved in related developmental defects.

Intracytoplasmic sperm injection (ICSI) is now used when severe male-factor infertility has been documented. Since defective mitochondrial functions may result in male hypofertility, it is of prime importance to evaluate the risk of paternal transmission of an mtDNA defect to neonates. DNA samples from the blood of 21 infertile couples and their 27 neonates born after ICSI were studied. The highly polymorphic mtDNA D-loop region was analyzed by four PCR-based approaches. With denaturing gradient gel electrophoresis (DGGE), which allows 2% of a minor mtDNA species to be detected, the 27 newborns had a DGGE pattern identical to that of their mother but different from that of their father. Heteroplasmy documented in several parents and children supported an exclusive maternal inheritance of mtDNA. The parental origin of the children's mtDNA molecules also was studied by more-sensitive assays: restriction-endonuclease analysis (REA) of alpha[32P]-radiolabeled PCR products; paternal-specific PCR assay; and depletion of maternal mtDNA, followed by REA. We did not detect paternal mtDNA in nine neonates, with a sensitivity level of 0.01% in five children, 0.1% in two children, and 1% in two children. The estimated ratio of sperm-to-oocyte mtDNA molecules in humans is 0.1%-1.5%. Thus, we conclude that, in these families, the ICSI procedure performed with mature spermatozoa did not alter the uniparental pattern of inheritance of mtDNA.

Familial Mediterranean fever (FMF) is a recessively inherited disorder that is common in patients of Armenian ancestry. To date, its diagnosis, which can be made only retrospectively, is one of exclusion, based entirely on nonspecific clinical signs that result from serosal inflammation and that may lead to unnecessary surgery. Renal amyloidosis, prevented by colchicine, is the most severe complication of FMF, a disorder associated with mutations in the MEFV gene. To evaluate the diagnostic and prognostic value of MEFV-gene analysis, we investigated 90 Armenian FMF patients from 77 unrelated families that were not selected through genetic-linkage analysis. Eight mutations, one of which (R408Q) is new, were found to account for 93% of the 163 independent FMF alleles, with both FMF alleles identified in 89% of the patients. In several instances, family studies provided molecular evidence for pseudodominant transmission and incomplete penetrance of the disease phenotype. The M694V homozygous genotype was found to be associated with a higher prevalence of renal amyloidosis and arthritis, compared with other genotypes (P=.0002 and P=.006, respectively). The demonstration of both the diagnostic and prognostic value of MEFV analysis and particular modes of inheritance should lead to new ways for management of FMF-including genetic counseling and therapeutic decisions in affected families.

Growth hormone insensitivity syndrome (GHIS) of genetic origin is associated with many different mutations of the growth hormone receptor (GHR) gene and a recently described genetic defect of the insulin-like growth factor I (IGF-I) gene. Phenotypic and biochemical features were examined in a cohort of 82 patients with GHIS from 23 countries. The mean age of these patients was 8.3 years, their mean height SDS was -6.09 and their median IGF-binding protein-3 (IGFBP-3) SDS was -8.5. In total, 19 of the 82 patients (23%) were growth hormone-binding protein (GHBP)-positive (> 10%). The mean heights in GHBP-negative and GHBP-positive patients were -6.45 SDS and -4.89 SDS, respectively (p < 0.001). Sixteen different GHR gene mutations were identified in 27 patients with GHIS. All of these patients had homozygous mutations, except one who had a compound heterozygous mutation. There was no relationship between the type or site within the GHR gene of the mutation and the height SDS or IGFBP-3 SDS of the patients. GHIS is associated with a wide variation in the severity of clinical and biochemical phenotypes. This variation cannot clearly be accounted for by defects in the GHR gene alone. Other genes or environmental factors must contribute to the control of growth in patients with GHIS.

The human GH receptor (hGHR) contains nine intracellular and seven extracellular cysteines, of which six are linked by disulfide bonds and one, at position 241 proximal to the membrane, is free. Recently, an alternatively spliced GHR isoform has been isolated; it encodes a truncated receptor lacking most of the cytoplasmic domain (hGHRtr). In the present study, we have examined the effect of sulfhydryl group(s) inactivation on receptor internalization and GH binding-protein (GHBP) generation from the human (h) and rabbit (rb) full-length GHR, as well as from hGHRtr and a mutant of the free extracellular cysteine (hGHRtr-C241A), expressed in Chinese hamster ovary (CHO) cells. In CHO/rbGHR and CHO/hGHR cells, permeable sulfhydryl-reactive agents, like N-ethylmaleimide (NEM) and iodacetamide (IA), inhibited GHR internalization and induced an immediate dose-dependent loss of cellular GHR, associated with a concomitant marked increase in released GHBP. In contrast, the membrane impermeable IA derivative A-484 had no effect on either GHBP release or on GHR internalization. NEM exposure of CHO cells, expressing hGHRtr, resulted in a dose-dependent increase in GHBP generation, but only a moderate decrease in cellular hGHRtr. The importance of the only unpaired cysteine in these processes was evaluated in CHO/hGHRtr-C241A cells. hGHRtr-C241A was similar to hGHRtr in its impaired internalization and enhanced GHBP release by NEM. Taken together, these data suggest that intracellular sulfhydryl groups, within membranal endocytic vesicles, that do not belong to the GHR molecule, are involved in receptor internalization and GHBP generation. In addition, the present study demonstrates that despite impaired hGHR internalization/down-regulation, the inducible release of GHBP was not affected, further suggesting that GHR endocytosis is not a prerequisite for GHBP generation.

Prop-1 is a newly isolated pituitary-specific paired-like homeodomain transcription factor whose cDNA sequence is well known in mouse. To study its involvement in human combined pituitary hormone deficiency (CPHD), we have isolated the human cDNA ortholog and determined the exon/intron organization and chromosomal localization of the human gene. A Prop-1 defect was characterized in three CPHD families. One missense mutation (R73C) involves a residue conserved in 95% of the more than 400 homeodomain proteins so far identified; in vitro splicing assays demonstrated the functional importance of the second defect, whereas the remaining mutation is a frameshift. Given the disease phenotype documented in the patients, these data, which will facilitate molecular investigations in other patients, demonstrate the crucial role of Prop-1 in the proper development of somatotrophs, lactotrophs, thyreotrophs and gonadotrophs.

Besides complete GH insensitivity syndrome (GHIS) described by Laron, clinical and molecular evidences have accumulated concerning partial GHIS. We studied GH receptor (GHR) gene in children who show poor response to GH treatment and detected a patient with a heterozygous mutation in exon 7 leading to the Y222H substitution. This missense mutation, located in the YGEFS motif of the GHR equivalent to the WSXWS motif highly conserved throughout all members of the cytokine receptor family, has not been described so far. Although we cannot conclude on the deleterious effect of this mutation, there are several lines of evidence suggesting that it could account for the partial GH insensitivity: (i) hormonal data including IGF-I generation test; (ii) molecular data - no other mutation was identified in the coding sequence, the father who has the same mutation is short, the brother did not inherit the mutated allele and was of normal height.

GH secretion and release are complex phenomena depending on activation of several genes, including those encoding GH, GHRH, and its receptor (GHRH-R). The GH gene, which is the most extensively analyzed sequence in patients with familial GH deficiency (GHD), represents the main known target of mutations. To test the involvement of the GHRH-R gene in this disease phenotype, we investigated one candidate Tamoulean family originating from Sri Lanka. Two brothers, with extremely short stature (< -4 SD) and no dysmorphy, were diagnosed as having complete GHD, unresponsive to exogenous GHRH and associated with PRL levels within the lower normal range. Magnetic resonance imaging examination showed anterior pituitary hypoplasia with a normal pituitary stalk. Both patients increased their growth rate while under GH therapy. Molecular investigations revealed a homozygous GHRH-R gene mutation that introduces a stop codon at residue 72. This mutation, which predicts a severely truncated receptor lacking the seven membrane spanning domains, is identical to that recently reported in one Indian Moslem family, raising the possibility of a founder effect. There was no clear evidence for height reduction in the three heterozygous individuals studied. This observation, which underlines the phenotypic criteria associated with a loss of GHRH-R function, raises the question of the frequency of GHRH-R abnormalities among GHD patients.

The soluble growth hormone binding protein (GHBP), which is encoded by the GH receptor (GHR) gene, is generated by several mechanisms. In rabbits (rb) and humans (h), it is derived by proteolytic cleavage of the full-length membrane-bound receptor molecules (GHR-fl), whereas in rats (r) and mice, it results from an alternative splice excluding the transmembrane domain. Furthermore, in all these species, alternative splicing in the cytoplasmic domain results in a truncated isoform (GHR-tr), that, in humans, produces large amounts of GHBP through proteolysis. To further characterize the species specificity of the mechanism underlying GHBP generation, rbGHR-tr and rGHR-tr expressed in COS-7 cells were assayed for their ability to produce a GHBP in comparison with the corresponding full-length receptors. Large amounts of GHBP were secreted by cells expressing the rabbit constructs, the rbGHR-tr isoform being more efficient in GHBP generation than rbGHR-fl. In contrast, no GHBP was detected from cells expressing rGHR-tr, the cytoplasmic deletion having no effect on GHBP release from membrane receptors. These data further demonstrate evolutionary divergence in the mechanism by which GHBP is generated and provide new clues to decipher the molecular process underlying the cleavage step.

Growth hormone (GH) insensitivity is associated with several different mutations of the GH receptor gene and a recently described new genetic disorder of the IFGI gene. The phenotype and biochemical characteristics were studied in 82 patients with growth hormone insensitivity, from 23 different countries, with a mean age of 8.25 years. Mean height SDS was -6.09. SDS of the IGF binding protein -3 (IGF BP3) was 7.99. Twenty three per cent of the patients were GH binding protein (GHBP) positive (> 10%). Mean height SDS score was -6.5 in the GHBP negative patients and -4.9 in the GHBP positive patients (p < 0.001). Fifteen different mutations of the GH receptor gene were identified in 27 patients. There were no relationships between the type of mutation or the involved GH receptor gene exon and height or IGFBP-3 SDS. The new phenotype due to a partial deletion of the IGFI gene was described in a 15-year-old boy who presented with a severe intrauterine growth retardation, a very poor postnatal statural growth, a neurosensorial deafness and a mild mental retardation. He had elevated GH levels, normal levels of IGFBP3, undetectable levels of IGFI, and showed no response to GH treatment. A partial deletion concerning the exons 4 and 5 of the IGFI gene was found. Thus, GH insensitivity is associated with large variations in the clinical and biochemical phenotypes.

To gain a better understanding of the molecular basisof mitochondrial (mt) encephalomyopathies, a highly heterogeneous condition, we developed a denaturing gradient gel electrophoresis-based approach that allows rapid and exhaustive screening for mutations of all 22 mt tRNA-encoding genes and their flanking regions in large cohorts of patients. This method, that detects heteroplasmy (i.e. co-existence of mutant and wild-type mtDNA species in various ratios) directly, was applied to the investigation of 35 independent patients with a disease phenotype compatible with a mitochondrial encephalomyopathy. Twenty-five of the 35 patients investigated displayed a sequence variation in at least one tRNA gene. A total of 46 different sequence variations (41 point mutations, four short insertions and one short deletion), among which 20 are new, were characterized. Forty of them were present in a homoplasmic state, whereas six were heteroplasmic. Twenty-two were located in tRNA genes, among which 10 are new homoplasmic or heteroplasmic sequence variations; 24 were located in flanking regions (12 in mRNA-encoding genes, seven of them leading to missense sequence variations; two in rRNA genes; and 10 in non-coding regions). This study demonstrates (i) the high frequency of homoplasmic tRNA gene sequence variations in our patient sample, and (ii) the existence of several polymorphic sites in tRNA gene regions that may be helpful for defining haplogroups in different populations. It relies on a screening method that can now be applied easily to other population samples.

GH insensitivity syndrome (GHIS) is associated with many different mutations of the GH receptor (GHR) gene. We examined the phenotypic and biochemical features in 82 GHIS patients from 23 countries, each fulfilling diagnostic criteria of GHIS. There were 45 males and 37 females [mean age, 8.25 yr; mean height, -6.09 SD score, and mean insulin-like growth factor (IGF)-binding protein-3 (IGFBP-3), -7.99 SD score]. Sixty-three were GH-binding protein (GHBP) negative; 19 were GHBP positive (> 10% binding). The mean height in GHBP-negative subjects was -6.5 SD score, and that in GHBP-positive patients was -4.9 SD score (P = < 0.001). Clinical and biochemical heterogeneity was demonstrated by the wide range of height (-2.2 to -10.4 SD score) and IGFBP-3 (-1.4 to -14.7 SD score) values, which were positively correlated (r2 = 0.45; P = < 0.001). This contrasted with the lack of correlation between mean parental height SD score and height SD score (r2 = 0.01). Fifteen different GH receptor gene mutations were identified in 27 patients. All had homozygous defects, except 1 who had a compound heterozygous defect. The mutations were 5 nonsense, 2 frame shift, 4 splice, 4 missense, and 1 compound heterozygote. There was no relationship between mutation type or exon of the GHR gene involved and height or IGFBP-3 SD score. In conclusion, GHIS is associated with wide variation in the severity of clinical and biochemical phenotypes. This variation cannot clearly be accounted for by defects in the GHR gene. Other genetic and/or environmental factors must, therefore, contribute to phenotype in GHIS.

Previously, we reported the identification of a new human GH receptor (hGHR) messenger RNA species that encodes a smaller hGHR isoform, termed hGHRtr. Its messenger RNA is expressed in several human tissues and predicts a severely truncated GHR protein that lacks 97.5% of the intracellular domain. Because these two hGHR isoforms, which display similar binding affinity, are coexpressed in several tissues, they may reside side by side and, therefore, interrelate. To further characterize the biological properties of hGHRtr in comparison with hGHR, we generated Chinese hamster ovary (CHO) cell lines stably expressing each of these hGHR isoforms. Cross-linking of [125I]hGH to CHO/hGHRtr cells revealed a majored specific complex with apparent Mr of approximately 100 kDa, which would indicate the hGHRtr to be in molecular mass form of about 80 kDa. When compared with CHO/hGHR, CHO/hGHRtr cells secreted higher amounts of soluble GH-binding protein (GHBP). In contrast to CHO/hGHR cells, CHO/hGHRtr cells did not exhibit any GH-induced receptor down-regulation, and internalization was markedly reduced. Analysis of the constitutive turnover of cellular hGHR and soluble GHBP showed that incubation of CHO/hGHR cells with cycloheximide caused parallel disappearance of hGHR and GHBP. This contrasted with the stability of GHRtr, which showed no decline after cycloheximide treatment for up to 4 h, suggesting that the bulk GHRtr and GHBP may be derived from preformed proteins. Thus, in contrast to hGHR, hGHRtr is fixed at the cell membrane; it undergoes minimal internalization, no down-regulation by hGH, no constitutive turnover for as long as 4 h, but increased capacity to generate a soluble GHBP. Because hGHRtr failed to undergo ligand-induced internalization, the source of the continuous, undisturbed GHBP released into the medium may be from an intracellular storage pool. The relative abundance of these two hGHR isoforms, through regulation of splicing, could be of critical importance in modulating the biological effects of GH.

The pharmacokinetics of dexanabinol (HU-211), a synthetic, nonpsychotropic cannabinoid with neuroprotectant action, was evaluated in a phase I clinical trial. The compound was administered at doses of 48 mg, 100 mg, and 200 mg as short i.v. infusions in a Cremophor-ethanol vehicle diluted with saline. All administrations were well-tolerated and no compound-related side-effects were observed. Plasma concentrations of dexanabinol were quantitated using a GC/MS/MS technique which provided a limit of quantitation of 100 pg/ml. The elimination of dexanabinol was best fitted to a 3-compartment model with a rapid distribution half-life (< 5 min), an intermediate phase half-life of approximately 90 min, and a slow terminal elimination half-life (approximately 9 h). The pharmacokinetics were linear over the evaluated dose range. The plasma clearance of the drug was high (1,700 ml/min) and the volume of distribution approximately 15 l/kg. These data are similar to those reported for naturally occurring cannabinoids such as delta 9-tetrahydrocannabinol and cannabidiol.

Dynein heavy chains (DHCs) are the main components of multisubunit motor ATPase complexes called dyneins. Axonemal dyneins provide the driving force for ciliary and flagellar motility. Recent molecular studies demonstrated that multiple DHC isoforms are produced by separate genes. We describe the isolation of five human axonemal DHC genes. Analysis of the human genomic clones revealed the existence of intronic sequences that were used to demonstrate that human axonemal DHC genes are located on different chromosomes. The cloned human DHC sequences were integrated into an evolutionary approach based on phylogenetic analysis. Tissue expression studies showed that these human axonemal DHCs are expressed in testis and/or trachea, two tissues with axonemal structures that can be altered in primary ciliary dyskinesia, making DHC genes strong candidates in the genesis of these human diseases.

Leprechaunism is a rare autosomal recessive disorder characterized by marked intrauterine and postnatal growth retardation, severe insulin resistance, and altered glucose homeostasis. This syndrome is related to mutations in the insulin receptor (IR) gene that impair the transmission of the insulin signal by several mechanisms. There is no effective therapy and patients usually die within the first months of life. Here we report the prenatal diagnosis of leprechaunism in two unrelated families in which affected children were compound heterozygotes with two different deficient IR alleles. In family Par-1, the disease IR alleles carried a missense mutation located in exon 18 (Arg1092-->Trp) and exon 20 (Glu1179-->Lys). In family Als, a 3-basepair deletion causing the loss of Asn281 in exon 3 and a major deletion of exons 10-13 were present in the maternal and paternal mutant IR alleles, respectively. Prenatal diagnosis was made in each family by a specific approach combining denaturing gradient gel electrophoresis (DGGE) and Southern blotting. This methodology allowed us to correctly predict the genotype of the two fetuses at the IR locus.

Laron syndrome (LS) is a hereditary form of GH resistance due to molecular defects in the GH receptor (GHR). Most of the identified mutations are located in the extracellular domain of the receptor, resulting in a lack of serum GHBP in the majority of LS patients. We present an LS patient with supranormal levels of serum GHBP, in addition to 35 of her relatives. The proband is a 3.5 year-old Druse girl with severe short stature (height SDS -5.1), high GH (250 micrograms/l), low IGF-I (2.7 nmol/l) and IGFBP-3 (410 micrograms/l), both unresponsive to exogenous GH. The binding capacity of the serum GHBP was 22 nM (adult reference serum, 0.7 nM), with an affinity constant Ka = 1.9 x 10(9) M-1 comparable to that of normal sera (Ka = 1.7-2.1 x 10(9) M-1). The apparent MW of the GHBP was approximately 60-80 kDa, similar to that of control sera. In the proband's sister, parents, grandparents and uncles, extremely high GHBP values were observed (43.0 +/- 4.8 RSB, n = 10) compared with normal adults (0.81 +/- 0.06 RSB) (p << 0.001). The remaining subjects had normal or moderately elevated GHBP levels. Serum GH in adults with high GHBP was significantly elevated above control values (6.0 +/- 0.9 micrograms/l vs 0.76 +/- 0.13 microgram/l, p < 0.001). Serum IGF-I and IGFBP-3 levels were normal in all the subjects, with the exception of an aunt (IGF-I 3.9 nmol/l) and the proband's sister (IGFBP-3 460 micrograms/l). All the subjects' heights were within the normal range. Analysis of the GHR gene performed in the proband revealed an as yet undescribed homozygous intronic point mutation. It consists of a G-->T substitution at nucleotide 785-1 preceding exon 8, a sequence that encodes the transmembrane domain. This mutation, which destroys the invariant dinucleotide of the splice acceptor site, is expected to alter GHR mRNA splicing and to be responsible for skipping exon 8. The resulting truncated protein that retains GH binding activity is probably no longer anchored in the cell membrane, affecting signal transmission in the homozygous patient and causing high GHBP levels in the heterozygous relatives.

The GH receptor (GHR) is a member of the cytokine receptor superfamily; GH binding protein is the solubilized extracellular domain of the GHR. Abnormalities in the GHR produce an autosomal recessive form of GH resistance, the Laron syndrome, characterized by growth failure and the clinical appearance of severe GH deficiency despite elevated circulating GH levels. In 13 unrelated patients with undetectable levels of GH binding protein, we characterized nine novel mutations in the GHR gene. These molecular defects comprise three nonsense mutations (Q65X, W80X, and W157X), one frameshift (36delC), two splice defects (G-->A at 70 + 1, C-->T at 723), and three missense mutations (C38S, S40L, and W50R) located in the extracellular domain of the receptor, and thus would be expected to interfere with GH binding activity. These results further confirm the broad heterogeneity of mutations underlying this rare GH resistance syndrome.

Intranasal immunization of mice with human immunodeficiency virus (HIV) rgp160 complexed to proteosomes improved anti-gp160 serum IgA and IgG titers, increased the number of gp160 peptides recognized, and stimulated anti-gp160 intestinal IgA compared with immunization with uncomplexed rgp160 in saline. These enhanced responses were especially evident when either a bioadhesive nanoemulsion (emulsomes) or cholera toxin B subunit (CTB) was added to the proteosome-rgp160 vaccine. Furthermore, anti-gp160 IgG and IgA in vaginal secretions and fecal extracts were induced after intranasal immunization with proteosome-rgp160 delivered either in saline or with emulsomes. Formulation of uncomplexed rgp160 with emulsomes or CTB also enhanced serum and selected mucosal IgA responses. Induction of serum, vaginal, bronchial, intestinal, and fecal IgA and IgG by intranasal proteosome-rgp160 vaccines delivered in saline or with emulsomes or CTB is encouraging for mucosal vaccine development to help control the spread of HIV transmission and AIDS.

We studied the biological properties of insulin receptors (IRs) and insulin-like growth factor-I (IGF-I) receptors in cultured fibroblasts from a patient with leprechaunism (leprechaun Par-1). Patient cells displayed normal insulin binding capacity and affinity. Basal in vivo autophosphorylation and in vitro exogenous kinase activity of patient IRs were elevated twofold to threefold compared with control receptors, and insulin had no further effect on these processes. Moreover, patient IRs were unable to promote the stimulation of metabolic and mitogenic pathways. IR substrate-1 (IRS-1) and mitogen-activated protein (MAP) kinase tyrosine phosphorylation and glycogen and DNA synthesis were not increased in the basal state in patient fibroblasts and were also insensitive to the stimulatory effect of insulin. As for IGF-I, although binding and receptor kinase activity were normal, the ability to stimulate glycogen and DNA synthesis was altered in patient cells. Two mutant alleles of the IR gene were detected by denaturing gradient gel electrophoresis (DGGE) and direct sequencing. The maternal allele contained a point mutation in exon 18 encoding the tryptophan-for-arginine substitution at position 1092, and the paternal allele had a point mutation in exon 20 substituting lysine for glutamic acid at codon 1179. Thereby, leprechaun Par-1 was a compound heterozygote for two missense mutations located in the IR beta-subunit. The present investigation provides the first evidence that leprechaunism can be causally related to structural alterations in the tyrosine kinase domain of the IR. These alterations result in severe impairment of insulin and IGF-I action.