PubMed Health⌕ Search

Biomedical subjects

J C Deybach

Publications and source records attributed to J C Deybach.

At least 19 recordsLinked to original sources
PubMed2006

Biochemical compared to molecular diagnosis in acute intermittent porphyria.

The biochemical and the molecular diagnoses of an inherited porphyria require experience. False positive or negative screening tests and the low penetrance of the disease make a correct diagnosis difficult.The biochemical and the molecular procedures for the diagnosis of acute intermittent porphyria were applied to five unrelated patients suffering from acute intermittent porphyria. All patients were shown to be gene carriers of acute intermittent porphyria by both methods. The two different possibilities of the diagnosis corresponded well. In a family definitively identified by molecular diagnosis of one of the patients and his relatives, the patient's two children were asymptomatic. His son was shown to be a gene carrier of the father's deficiency by biochemical as well as molecular analysis, whereas his daughter was not affected by acute intermittent porphyria.

Adolescent↗
PubMed2002

A molecular, enzymatic and clinical study in a family with hereditary coproporphyria.

A 30-year-old woman suffered from acute crises with abdominal, neurological and psychiatric complaints. Urinary haem precursors and faecal porphyrins were excessively elevated compared to the upper level of the normal range. Urinary coproporphyrin isomer III was increased and faecal coproporphyrin isomers I and III showed a complete inversion of the normal ratio. Thus, hereditary coproporphyria was diagnosed in this woman. The father, one brother and a sister were shown to be gene carriers of hereditary coproporphyria by their urinary and faecal excretory constellations. The excretory patterns of the mother and a second brother were normal. Coproporphyrinogen oxidase activity was decreased to 49% and 58%, in the patient and her father, respectively. The mother's enzyme activity was normal (98%). Coproporphyrinogen oxidase concentration was enhanced 1.8-fold and 2.7-fold in the patient and her father, respectively. Mutation analysis revealed the insertion of an adenine at position 857 in exon 4 of the coproporphyrinogen oxidase gene. The gene defect was confirmed by denaturing gradient gel electrophoresis in the patient and her father. The patient was treated by intravenous interval therapy with haem arginate for 10 months, with good clinical and metabolic response.

Adult↗
PubMed2002

Molecular, immunological, enzymatic and biochemical studies of coproporphyrinogen oxidase deficiency in a family with hereditary coproporphyria.

A 27-year-old woman who had recurrent pain in renal bed since 1998 with increasing character, was stationary admitted. The patient showed dark urine, complained of hair loss and took since 1994 a hormonal oral contraceptive. No photosensitivity was observed. Determinations of urinary porphyrin metabolites in 1998 revealed a porphyria cutanea tarda like excretion pattern with elevations of uro- (1767 nmol/24 hr, normal <29 nmol/24 hr) and heptacarboxyporphyrin (568 nmol/24 hr; normal <4 nmol/24 hr). Follow-up studies in feces showed the characteristics of a hereditary coproporphyria with dominance of coproporphyrin isomer III (total= 1470 nmol/g, isomer III= 93%), (normal: <37 nmol/g, isomer III = 25-35%). The excretion of porphyrin precursors (delta-aminolevulinic acid and porphobilinogen) was increased by taking an ethinylestradiol-cyproteronacetate-preparation, but acute and/or chronic manifestations were not observed. Coproporphyrinogen oxidase activity was decreased to 35% in the patient (normal=138+/-21 pkat/g protein; x+/-s), whereas the activity of red cell uroporphyrinogen decarboxylase was normal. Her mother and both sisters could be verified as heterozygous gene carriers of hereditary coproporphyria by their urinary and fecal excretion parameters and because of reduced coproporphyrinogen oxidase activity up to 50%. The father was normal with respect to his genotype. Molecular analysis revealed a hitherto unknown mutation with the transversion of a cytosine to thymine at nucleotide position 854 in exon 4 of the coproporphyrinogen oxidase gene. The gene defect was confirmed by DGGE in the mother and her three daughters. The investigation of the immunological nature of the defective coproporphyrinogen oxidase gene from the whole family revealed decreased concentrations of coproporphyrinogen oxidase protein in the patient, her mother and her two sisters.

Adult↗
PubMed2002

A genotype-phenotype correlation between null-allele mutations in the ferrochelatase gene and liver complication in patients with erythropoietic protoporphyria.

Erythropoietic protoporphyria (EPP), an inborn error of heme metabolism, causes in the majority of the patients only a symptom of photosensitivity. However, around 2% of the EPP sufferers develop liver complication in the form of liver cirrhosis and progressive liver failure. Mutations in the human ferrochelatase (FECH) gene causing EPP are highly heterogeneous and mostly family-specific. Actually, 62 FECH mutations have been published, 48 of them are "null allele" mutations inducing the formation of a truncated protein. The remaining 14 are missense mutations. In contrast to the null allele mutations, the latter lead to substitution of a single amino acid residue in the protein molecule and generate an enzyme that, although functionally impaired, is in its full length. In order to study the association between "null allele" mutation and liver complication, we combined our data with those in the literature. A total of 112 EPP patients were counted among 93 EPP families with a known FECH mutation. All 18 EPP patients who had severe liver complication carried a "null allele" mutation. In contrast, none of the 20 patients who carried a missense mutation had developed liver complication till the time of study (Fisher's exact test, p<0.05). High protoporphyrin blood concentration are considered to be a sign of an increased risk of liver disease. No correlation of protoporphyrin blood level with the type of mutation, was found, if patients with overt liver disease were excluded from the sample. Furthermore, no significant association of the liver complication with the location of the mutation within the FECH gene was found (Fisher exact test p = 0.46). These available data indicate a significant genotype-phenotype correlation between "null allele" mutation and protoporphyrin related liver disease in EPP. Although the risk for a EPP patient with a missense mutation to develop liver disease cannot be totally eliminated based on these data, it is comparably low.

Alleles↗
PubMed2001

Characterization of mutations in the CPO gene in British patients demonstrates absence of genotype-phenotype correlation and identifies relationship between hereditary coproporphyria and harderoporphyria.

Hereditary coproporphyria (HCP) is the least common of the autosomal dominant acute hepatic porphyrias. It results from mutations in the CPO gene that encodes the mitochondrial enzyme, coproporphyrinogen oxidase. A few patients have also been reported who are homoallellic or heteroallelic for CPO mutations and are clinically distinct from those with HCP. In such patients the presence of a specific mutation (K404E) on one or both alleles produces a neonatal hemolytic anemia that is known as "harderoporphyria"; mutations on both alleles elsewhere in the gene give rise to the "homozygous" variant of HCP. The molecular relationship between these disorders and HCP has not been defined. We describe the molecular investigation and clinical features of 17 unrelated British patients with HCP. Ten novel and four previously reported CPO mutations, together with three previously unrecognized single-nucleotide polymorphisms, were identified in 15 of the 17 patients. HCP is more heterogeneous than other acute porphyrias, with all but one mutation being restricted to a single family, with a predominance of missense mutations (10 missense, 2 nonsense, 1 frameshift, and 1 splice site). Of the four known mutations, one (R331W) has previously been reported to cause disease only in homozygotes. Heterologous expression of another mutation (R401W) demonstrated functional properties similar to those of the K404E harderoporphyria mutation. In all patients, clinical presentation was uniform, in spite of the wide range (1%-64%) of residual coproporphyrinogen oxidase activity, as determined by heterologous expression. Our findings add substantially to knowledge of the molecular epidemiology of HCP, show that single copies of CPO mutations that are known or predicted to cause "homozygous" HCP or harderoporphyria can produce typical HCP in adults, and demonstrate that the severity of the phenotype does not correlate with the degree of inactivation by mutation of coproporphyrinogen oxidase.

Amino Acid Sequence↗
PubMed2001

Association and excess of transmission of a DRD2 haplotype in a sample of French schizophrenic patients.

The gene which codes for dopamine receptor D2 (DRD2) is considered as one of the most relevant candidate genes in schizophrenia. Previous genetic studies focusing on this gene gave conflicting results, potentially because of the differences in methodology (linkage versus association studies), and the different loci analyzed (the DRD2 gene having many polymorphisms). We used a progressive strategy with three different approaches (case/control, haplotype relative risk and transmission disequilibrium test) and investigated two genetic polymorphisms (TaqI B1/B2 and TaqI A1/A2, spanning the coding region of the DRD2 gene) in 50 patients with DSM-IV diagnoses of schizophrenia, in their 100 parents and in 50 healthy, matched controls. Firstly, we found a significant excess of the two alleles (B2 and A2) in the schizophrenic group compared to unaffected controls. Secondly, we found an excess of transmission from the parents to their affected children, using the haplotype relative risk design applied to the B2A2 haplotype. Finally, the transmission disequilibrium test showed evidence for linkage between B2A2 haplotype and schizophrenia. The significant excess of the B2A2 haplotype in schizophrenic patients is specifically observed in a subsample of patients with a disease onset occurring after 20 years of age. As the haplotype contains nearly the entire DRD2 gene, we found convergent evidence in our sample for a significant role of the DRD2 gene in the risk for schizophrenia. This haplotype may be more specifically involved in the disorder's onset at a later age in some patients, or, alternatively, may be implicated as a modifying factor acting on age of onset.

Adult↗
PubMed2001

Haplotype analysis in determination of the heredity of erythropoietic protoporphyria among Swiss families.

Defects in the human ferrochelatase gene lead to the hereditary disorder of erythropoietic protoporphyria. The clinical expression of this autosomal dominant disorder requires an allelic combination of a disabled mutant allele and a low-expressed nonmutant allele. Unlike most other erythropoietic protoporphyria populations, mutations identified among Swiss erythropoietic protoporphyria families to date have been relatively homogeneous. In this study, genotype analysis was conducted in seven Swiss erythropoietic protoporphyria families, three carrying mutation Q59X, two carrying mutation insT213, and two carrying mutation delTACAG(580-584). Three different haplotypes of five known intragenic single nucleotide polymorphisms, namely -251 A/G, IVS1-23C/T, 798 G/C, 921 A/G, and 1520C/T, were identified. Each haplotype was shared by families carrying an identical mutation in the ferrochelatase gene indicating a single mutation event for each of the three mutations. These mutations have been present in the Swiss erythropoietic protoporphyria population for a relatively long time as no common haplotypes of microsatellite markers flanking the ferrochelatase gene were found, except of two conserved regions, telomeric of the insT213 allele and centromeric of the delTACAG(580-584)allele, each with a size > 3 cM. Among the nonmutant ferrochelatase alleles, patients from six erythropoietic protoporphyria families shared a common haplotype [-251G; IVS1-23T] of the first two single nucleotide polymorphisms. An exception was the haplotype [-251 A; IVS1-23C] identified in the index patient of one erythropoietic protoporphyria family. These results supported the recent findings that the low expressed allele is tightly linked to a haplotype [-251G; IVS1-23T] of two intragenic single nucleotide polymorphisms in the ferrochelatase gene.

Family Health↗
PubMed2001

Influence of age and gender on the clinical expression of acute intermittent porphyria based on molecular study of porphobilinogen deaminase gene among Swiss patients.

BACKGROUND: Acute intermittent porphyria (AIP) is an inherited disorder in the heme biosynthetic pathway caused by a partial deficiency of porphobilinogen (PBG) deaminase. Clinically, AIP is characterized as acute neurovisceral attacks that are often precipitated by exogenous factors such as drugs, hormones, and alcohol. An early detection of mutation carriers is essential for prevention of acute attacks by avoiding precipitating factors. This study was aimed at analyzing genetic defects causing AIP among Swiss families to further investigate aspects concerning the clinical expression of the disease. MATERIALS AND METHODS: The PBGD gene of index patients from 21 Swiss AIP families was systematically analyzed by denaturing gradient gel electrophoresis of polymerase chain reaction (PCR) amplified DNA fragments and direct sequencing. RESULTS: Five new mutations insA503, del L170, T190I, P241S, and R321H, as well as three known mutations (R26H, R173Q and W283X) were detected. Twelve of the 21 index patients (57%) carried the prevalent mutation W283X previously found among the Swiss AIP population. Family-specific mutations were then screened among relatives of the index patients. Among the 107 studied individuals, 58 carried a PBGD gene mutation--30 were overt AIP patients and 28 were asymptomatic carriers. The apparent rate of overt disease in the study cohort was 52%, which is significantly higher than the previously reported penetrance of 10-20%. To further examine the clinical expression of AIP, the cumulative life-time risk was calculated among 58 mutation-positive individuals after stratifying for age. The result shows a linear increase of the percentage of the symptomatic patients with age, reaching up to 75% among carriers aged over 60. Moreover, statistical analysis of the gender distribution among patients and asymptomatic carriers indicated that the disease was more frequently expressed among females than males (Fisher's exact test two sided, p= (0.001). CONCLUSIONS: This comprehensive search for genetic defects in the PBGD gene confirmed the existence of a prevalent mutation W283X among Swiss AIP patients, as well as a number of family-private mutations. Genetic analysis laid a groundwork for further studies such as the effects of gender and age on the clinical expression of AIP.

Adolescent↗
PubMed2000

Mutations in the iron-sulfur cluster ligands of the human ferrochelatase lead to erythropoietic protoporphyria.

Ferrochelatase (FECH; EC 4.99.1.1) catalyzes the terminal step of the heme biosynthetic pathway. Defects in the human FECH gene may lead to erythropoietic protoporphyria (EPP), a rare inherited disorder characterized by diminished FECH activity with protoporphyrin overproduction and subsequent skin photosensitivity and in rare cases liver failure. Inheritance of EPP appeared to be autosomal dominant with possible modulation by low expression of the wild-type FECH allele. Animal FECHs have been demonstrated to be [2Fe-2S] cluster-containing proteins. Although enzymatic activity and stability of the protein appear to be dependent on the presence of the [2Fe-2S] cluster, the physiologic role of the iron-sulfur center remains to be unequivocally established. Three of the 4 [2Fe-2S] cluster-coordinating cysteines (ie, C403, C406, and C411 in the human enzyme) are located within the C-terminal domain. In this study 5 new mutations are identified in patients with EPP. Three of the point mutations, in 3 patients, resulted in FECH variants with 2 of the [2Fe-2S] cluster cysteines substituted with tyrosine, serine, and glycine (ie, C406Y, C406S, and C411G) and with undetectable enzymatic activity. Further, one of the patients exhibited a triple point mutation (T(1224)-->A, C(1225)-->T, and T(1231)-->G) leading to the N408K/P409S/C411G variant. This finding is entirely novel and has not been reported in EPP. The mutations of the codons for 2 of the [2Fe-2S] cluster ligands in patients with EPP supports the importance of the iron-sulfur center for the proper functioning of mammalian FECH and, in at least humans, its absence has a direct clinical impact. (Blood. 2000;96:1545-1549)

Female↗
PubMed2000

New insights into the pathogenesis of erythropoietic protoporphyria and their impact on patient care.

UNLABELLED: Erythropoietic protoporphyria (EPP, MIM 177000) is an inherited disorder caused by a partial deficiency of ferrochelatase (FECH) which catalyses the chelation of iron into protoporphyrin to form haem. The majority of EPP patients experience solely a painful photosensitivity whereas a small number of them develop liver complications due to the accumulation of excessive amount of protoporphyrin in the liver. EPP is considered to be an autosomal dominant disorder, however, with a low clinical penetrance. To date, a total of 65 different mutations have been identified in the FECH gene of EPP patients. Among the 89 EPP patients who carry a "null allele" mutation which results in the formation of a truncated protein, 18 of them developed EPP-related liver complications. None of the 16 missense mutations identified among 19 patients on the other hand, have been associated with liver disease (P = 0.038). The allelic constellation of an overt patient consists of a mutated FECH allele and a "low expressed" normal allele and that of an asymptomatic carrier, a combination of a mutated and a normally expressed FECH allele. The identification of the "low expressed" allele is facilitated by haplotype analysis using two single nucleotide polymorphisms, -251 A/G in the promoter region and IVS1-23C/T. At the current time when only partially effective therapies are available, the disclosures of both "null allele" and the "low expression" mechanisms will improve patient management. CONCLUSION: While covering the important clinical aspect of erythropoietic protoporphyria, this article emphasises the latest achievements in the molecular genetics of the disorder.

Alleles↗
PubMed2000

Porphobilinogen deaminase gene in African and Afro-Caribbean ethnic groups: mutations causing acute intermittent porphyria and specific intragenic polymorphisms.

Acute intermittent porphyria (AIP), the most common acute hepatic porphyria, is a low-penetrant autosomal dominant disorder caused by mutations in the porphobilinogen deaminase (PBGD) or hydroxymethylbilane synthase (HMBS) gene. Although AIP has been identified in all the main ethnic groups, little is known about PBGD gene defects in Africans, Afro-Caribbean and Afro-Americans. We have carried out PBGD gene screening among seven unrelated AIP families and 98 controls belonging to the Afro-Caribbean (French West Indies) and the sub-Saharan African (Morocco, Algeria, Cameroon, Mali, and Burkina Faso) populations. Using denaturing-gradient gel electrophoresis (DGGE) and direct sequencing we characterized six different mutations, including four novel, from the seven AIP families: three splicing defects (IVS 5+2 Ins G; IVS 7+1 G to A in two families; IVS 10-1 G to T); a small deletion (1004 Del G); and two missense mutations (R116 W; A270G). The allele frequencies of the 14 polymorphic sites, previously known in the normal Caucasian population, were similar in Africans and Afro-Caribbean control populations. Interestingly, two common new intragenic polymorphic sites, close to intron/junction boundaries, were identified only in blacks: 1) in intron 2, a single base-pair G deletion at position 3167 (G:0.88; delG:0.12); 2) in intron 10, a A/G dimorphism at position 7052 (A:0.56; G:0.44). These two single nucleotide polymorphisms (SNPs) were never encountered in 750 unrelated Caucasian subjects. The allele frequency distributions of populations within black ethnic groups (Africans and Afro-Caribbean) are similar. This study highlights differences both in PBGD gene mutations causing AIP and in SNPs between white and black peoples; the allele frequencies provided contribute to a better knowledge of the variability of these markers among the major population groups, especially in sub-Saharan West African and Afro-Caribbean populations.

Adolescent↗
PubMed2000

Hepatocellular carcinoma in patients with acute hepatic porphyria: frequency of occurrence and related factors.

BACKGROUND/AIMS: Previous retrospective studies have suggested an association between hepatocellular carcinoma and acute hepatic porphyrias. The incidence, the relative risk, the characteristics and the outcome of primary liver cancer were prospectively evaluated in patients with acute hepatic porphyrias; the molecular mechanism of carcinogenesis in these patients was also pointed out. METHODS: A cohort of 650 patients with acute hepatic porphyria was followed over 7 years. Standardized rate ratio was used to measure the relative risk of primary liver cancer after indirect standardization. Morphological and clinical aspects of primary liver cancer were investigated, and survival rates were calculated using the Kaplan-Meier method. Common etiological factors involved in liver carcinogenesis were screened. Excretion rates of porphyrin precursors, serum melatonin levels and mutations in the genes encoding for heme biosynthetic enzymes were studied. RESULTS: Hepatocellular carcinoma was found in four symptomatic and three asymptomatic patients (four female, three male). The overall standardized rate ratio was 36 (95% CI: 14-74). The 5-year disease-free survival was 43% in patients with hepatocellular carcinoma. Usual risk factors for primary liver cancer were not confounding factors. Hepatocellular carcinoma was not related to specific heme biosynthesis gene mutations. Heme precursors were significantly increased in porphyric patients with hepatocellular carcinoma, and serum melatonin levels were low. CONCLUSIONS: Acute hepatic porphyrias are risk factors for hepatocellular carcinoma. Hepatic porphyrias should be sought in patients with hepatocellular cancer without obvious etiology, and a periodic screening for hepatocellular carcinoma should be evaluated in these patients. Genes encoding for heme biosynthetic pathway may not act as tumor suppressor genes. Chronic increased levels of delta aminolevulinic acid could lead to the generation of free radicals and subsequently to hepatic carcinogenesis.

Acute Disease↗
PubMed2000

Amantadine for chronic hepatitis C: pilot study in 14 patients.

BACKGROUND: Amantadine, a widely available antiviral drug, has been previously reported to be effective in patients with chronic hepatitis C who failed to respond to interferon-alpha therapy. Nevertheless, its efficacy has not been fully studied, particularly in naive patients. OBJECTIVE AND DESIGN: We conducted a pilot study to determine the efficacy and the safety of amantadine as initial therapy in patients with chronic hepatitis C. METHODS AND PARTICIPANTS: Fourteen consecutive patients (mean age, 40 years; M/F ratio, 9/5) with chronic hepatitis C, elevated alanine aminotransferase (ALT) and without cirrhosis were treated with a 6-month course of amantadine, 100 mg orally twice daily. Main outcome measures were ALT concentrations and serum hepatitis C virus-RNA (HCV-RNA) levels at the end of therapy. RESULTS: All adverse events were mild or moderate and were not treatment limiting. At the end of treatment, all patients had detectable serum HCV-RNA and only one patient had a normal ALT level. The serum HCV-RNA median level and the ALT median level were not significantly different at the end of treatment as compared to baseline levels. CONCLUSIONS: Our results show that amantadine alone cannot be recommended as an alternative therapy in patients with chronic hepatitis C.

Administration, Oral↗
PubMed1999

Inheritance in erythropoietic protoporphyria: a common wild-type ferrochelatase allelic variant with low expression accounts for clinical manifestation.

Erythropoietic protoporphyria (EPP) is a rare autosomal dominant disorder of heme biosynthesis characterized by partial decrease in ferrochelatase (FECH; EC 4.99.1.1) activity with protoporphyrin overproduction and consequent painful skin photosensitivity and rarely liver disease. EPP is normally inherited in an autosomal dominant pattern with low clinical penetrance; the many different mutations that have been identified are restricted to one FECH allele, with the other one being free of any mutations. However, clinical manifestations of dominant EPP cannot be simply a matter of FECH haploinsufficiency, because patients have enzyme levels that are lower than the expected 50%. From RNA analysis in one family with dominant EPP, we recently suggested that clinical expression required coinheritance of a normal FECH allele with low expression and a mutant FECH allele. We now show that (1) coinheritance of a FECH gene defect and a wild-type low-expressed allele is generally involved in the clinical expression of EPP; (2) the low-expressed allelic variant was strongly associated with a partial 5' haplotype [-251G IVS1-23T IVS2microsatA9] that may be ancestral and was present in an estimated 10% of a control group of Caucasian origin; and (3) haplotyping allows the absolute risk of developing the disease to be predicted for those inheriting FECH EPP mutations. EPP may thus be considered as an inherited disorder that does not strictly follow recessive or dominant rules. It may represent a model for phenotype modulation by mild variation in expression of the wild-type allele in autosomal dominant diseases.

Alleles↗
PubMed1999

Systematic analysis of coproporphyrinogen oxidase gene defects in hereditary coproporphyria and mutation update.

Hereditary coproporphyria (HC) is an acute hepatic porphyria with autosomal dominant inheritance caused by deficient activity of coproporphyrinogen III oxidase (CPO). Clinical manifestations of the disease are characterized by acute attacks of neurological dysfunction often precipitated by drugs, fasting, cyclical hormonal changes, or infectious diseases. Skin photosensitivity may also be present. The seven exons, the exon/intron boundaries and part of 3' noncoding sequence of the CPO gene were systematically analyzed by an exon-by-exon denaturing gradient gel electrophoresis (DGGE) strategy followed by direct sequencing in seven unrelated heterozygous HC patients from France, Holland, and Czech Republic. Seven novel mutations and two new polymorphisms were detected. Among these mutations: two are missense (G197W, W427R), two are nonsense (Q306X, Q385X), two are small deletions (662de14bp; 1168del3bp removing a glycine at position 390), and one is a splicing mutation (IVS1-15c-->g) which creates a new acceptor splice site. The pathological significance of the point mutations G197W, W427R, and the in-frame deletion 390delGly were assessed by their respective expression in a prokaryotic system using site-directed mutagenesis. These mutations resulted in the absence or a dramatic decrease of CPO activity. The two polymorphisms were localized in noncoding part of the gene: 1) a C/G polymorphism in the promotor region, 142 bp upstream from the transcriptional initiation site (-142C/G), and 2) a 6 bp deletion polymorphism in the 3' noncoding part of the CPO gene, 574 bp downstream of the last base of the normal termination codon (+574 delATTCTT). Five intragenic dimorphisms are now well characterized and the high degree of allelic heterogeneity in HC is demonstrated with seven new different mutations making a total of nineteen CPO gene defects reported so far.

Adult↗
PubMed1999

New mutations of the hydroxymethylbilane synthase gene in German patients with acute intermittent porphyria.

Acute intermittent porphyria (AIP) is a low-penetrant, autosomal dominant disorder caused by decreased activity of hydroxymethylbilane synthase (HMBS; MIM 176 000), the third enzyme in the heme biosynthetic pathway. We report the first molecular analysis of HMBS gene mutations in classical AIP patients of German origin. The HMBS gene of 5 German AIP patients was analysed by DGGE-screening and direct sequencing of amplified genomic DNA. Five different mutations including four novel mutations were found. Three of them are single base substitutions that affected exon 3 (R16C), exon 10 (V202L), and intron 13 (T to A, IVS13+2) The two remaining mutations are frameshifts which produce a stop codon (del GA in exon 6 and insA in exon 14). These mutations are likely to be responsible for the decrease in HMBS activity found in both erythrocytes and non-erythroid cell lines (lymphocytes). Our results demonstrate the allelic heterogeneity of HMBS mutations in AIP patients of German origin.

Adolescent↗