A proposed molecular diagnostic flowchart for myophosphorylase deficiency (McArdle disease) in blood samples from Spanish patients

McArdle disease is a metabolic myopathy due to molecular defects in the myophosphorylase gene (PYGM), usually diagnosed in muscle biopsy. The aims of this study were to characterize genetically a large series of patients and to establish a protocol of molecular diagnosis on blood samples. We studied 55 Spanish unrelated patients with McArdle disease. Screening for the three more frequent mutations in the PYGM gene in the Spanish population (c.148C>T, p.R50X; c.613G>A, p.G205S; and c.2392T>C, p.W798R) were performed with polymerase chain-reaction and restriction fragment length polymorphism (PCR-RFLP) methods. To identify other mutant alleles, the coding region of PYGM gene was sequenced. The p.R50X mutation was observed in 38 patients, the p.G205S substitution in eight, and the p.W798R change in nine. Nine novel mutations, five missense (c.247A>T, p.I83F; c.521G>A, p.G174D; c.1094C>T, p.A365V; c.1468C>T, p.R490W; and c.1730A>G, p.Q577R), one nonsense mutation (c.2352C>A, p.C784X), three frameshift (c.402del, p.N134KfsX161; c.212_218dup, p.Q73HfsX7; c.1470dup, p.R491AfsX7), and nine previously reported mutations were found. In addition, we also updated the molecular data of 95 unrelated patients with McArdle disease studied thus far in our center. Of these patients, 56 were either homozygous or compound heterozygous for the p.R50X, p.G205S, or p.W798R mutation. By including in the molecular diagnosis protocol sequencing of the exons 1, 14, 17 and 18 of the PYGM gene, 16 further patients were characterized, and therefore we were able to detect the molecular defect in 72 out of 95 patients. A proposed molecular diagnosis protocol of the disease based on blood DNA would avoid muscle biopsy in 75.8% [95% confidence interval (95% CI): 62.1%-78.6%] of patients with McArdle disease.     

Identification of the bruton tyrosine kinase (BTK) gene mutations in 20 Australian families with X-linked agammaglobulinemia (XLA)

X-linked agammaglobulinemia (XLA) is an immunodeficiency caused by mutations in the Bruton tyrosine kinase (BTK) gene. Twenty Australian patients with an XLA phenotype, from 15 unrelated families, were found to have 14 mutations. Five of the mutations were previously described c.83G>A (p.R28H), c.862C>T (p.R288W), c.904G>A (p.R302G), c.1535T>C (p.L512P), c.700C>T (p.Q234X), while nine novel mutations were identified: four missense c.82C>A (p.R28S), c.494G>A (p.C165Y), c.464G>A (p.C155Y), c.1750G>A (p.G584E), one deletion c.142_144delAGAAGA (p.R48_G50del), and four splice site mutations c.241-2A>G, c.839+4A>G, c.1350-2A>G, c.1566+1G>A. Carrier analysis was performed in 10 mothers and 11 female relatives. The results of this study further support the notion that molecular genetic testing represents an important tool for definitive and early diagnosis of XLA and may allow accurate carrier status and prenatal diagnosis.     

Mutational analysis of mucopolysaccharidosis type VI patients undergoing a trial of enzyme replacement therapy

Mucopolysaccharidosis type VI (MPS VI), or Maroteaux-Lamy syndrome, is a lysosomal storage disorder caused by a deficiency of N-acetylgalactosamine-4-sulfatase (ARSB). Seven MPS VI patients were chosen for the initial clinical trial of enzyme replacement therapy. Direct sequencing of genomic DNA from these patients was used to identify ARSB mutations. Each individual exon of the ARSB gene was amplified by PCR and subsequently sequenced. Nine substitutions (c.289C>T [p.Q97X], c.629A>G [p.Y210C], c.707T>C [p.L236P], c.936G>T [p.W312C], c.944G>A [p.R315Q], c.962T>C [p.L321P], c.979C>T [p.R327X], c.1151G>A [p.S384N], and c.1450A>G [p.R484G]), two deletions (c.356_358delTAC [p.Y86del] and c.427delG), and one intronic mutation (c.1336+2T>G) were identified. A total of 7 out of the 12 mutations identified were novel (p.Y86del, p.Q97X, p.W312C, p.R327X, c.427delG, p.R484G, and c.1336+2T>G). Two of these novel mutations (p.Y86del and p.W312C) were expressed in Chinese hamster ovary cells and analyzed for residual ARSB activity and mutant ARSB protein. The two common polymorphisms c.1072G>A [p.V358M] and c.1126G>A [p.V376M] were identified among the patients, along with the silent mutation c.1191A>G. Cultured fibroblast ARSB mutant protein and residual activity were determined for each patient, and, together with genotype information, were used to predict the expected clinical severity of each MPS VI patient.     

Identification of 25 new mutations in 40 unrelated Spanish Niemann-Pick type C patients: genotype-phenotype correlations

To better characterize Niemann-Pick type C (NPC) in Spain and improve genetic counselling, molecular analyses were carried out in 40 unrelated Spanish patients. The search identified 70/80 alleles (88%) involving 38 different NPC1 mutations, 26 of which are described for the first time. No patient with NPC2 mutations was identified. The novel NPC1 mutations include 14 amino acid substitutions [R372W (c.1114C>T), P434L (c.1301C>T), C479Y (c.1436G>A), K576R (c.1727G>A), V727F (c.2179G>T), M754K (c.2261T>A), S865L (c.2594C>T), A926T (c.2776G>A), D948H (c.2842G>C), V959E (c.2876T>A), T1036K (c.3107C>A), T1066N (c.3197C>A), N1156I (c.3467A>T) and F1224L (c.3672C>G)], four stop codon [W260X (c.780G>A), S425X (c.1274C>A), C645X (c.1935T>A) and R1059X (c.3175C>T)], two donor splice-site mutations [IVS7+1G>A (g.31432G>A) and IVS21+2insG (g.51871insG)], one in-frame mutation [N961_F966delinsS (c.2882del16bpins1bp)] and five frameshift mutations [V299fsX8 (c.895insT), A558fsX11 (c.1673insG), C778fsX10 (c.2334insT), G993fsX3 (c.2973_78delG) and F1221fsX20 (c.3662delT)]. We also identified three novel changes [V562V (c.1686G>A), A580A (c.1740C>G) and A1187A (c.3561G>T)] in three independent NPC patients and five polymorphisms that have been described previously. The combination of these polymorphisms gave rise to the establishment of different haplotypes. Linkage disequilibrium was detected between mutations C177Y and G993fsX3 and specific haplotypes, suggesting a unique origin for these mutations. In contrast, I1061T mutation showed at least two different origins. The most prevalent mutations in Spanish patients were I1061T, Q775P, C177Y and P1007A (10, 7, 7 and 5% of alleles, respectively). Our data in homozygous patients indicate that the Q775P mutation correlates with a severe infantile neurological form and the C177Y mutation with a late infantile clinical phenotype.     

Molecular characterization of Italian nevoid basal cell carcinoma syndrome patients

Mutations in the PTCH gene, the human homolog of the Drosophila patched gene, have been found to lead to the autosomal dominant disorder termed Nevoid Basal Cell Carcinoma Syndrome (NBCCS, also called Gorlin Syndrome). Patients display an array of developmental anomalies and are prone to develop a variety of tumors, with multiple Basal Cell Carcinomas occurring frequently. We provide here the results of molecular testing of a set of Italian Nevoid Basal Cell Carcinoma Syndrome patients. Twelve familial patients belonging to 7 kindreds and 5 unaffected family members, 6 non-familial patients and an additional set of 7 patients with multiple Basal Cell Carcinoma but no other criteria for the disease were examined for mutations in the PTCH gene. All of the Nevoid Basal Cell Carcinoma Syndrome patients were found to carry variants of the PTCH gene. We detected nine novel mutations (1 of which occurring twice): 1 missense mutation (c.1436T>G [p.L479R]), 1 nonsense mutation (c.1138G>T [p.E380X]), 6 frameshift mutations (c.323_324ins2, c.2011_2012dup, c.2535_2536dup, c.2577_2583del, c.3000_3005del, c.3050_3051del), 1 novel splicing variant (c.6552A>T) and 3 mutations that have been previously reported (c.3168+5G>A, c.1526G>T [p.G509V], and c.3499G>A [p.G1167R]). None of the patients with multiple Basal Cell Carcinoma but no other criteria for the syndrome, carried germline coding region mutations.     

Identification of eight novel glucokinase mutations in Italian children with maturity-onset diabetes of the young

Maturity-onset diabetes of the young (MODY) is a clinically heterogeneous group of disorders characterized by early onset non-insulin-dependent diabetes mellitus, autosomal dominant inheritance, and primary defect in the function of the beta cells of the pancreas. Mutations in the glucokinase (GCK) gene account for 8%-56% of MODY, with the highest prevalences being found in the southern Europe. While screening for GCK mutations in 28 MODY families of Italian origin, we identified 17 different mutations (corresponding to 61% prevalence), including eight previously undescribed ones. The novel sequence variants included five missense mutations (p.Lys161Asn c.483G>C in exon 4, p.Phe171Leu c.511T>C in exon 5 and p.Thr228Ala c.682A>G, p.Thr228Arg c.683C>G, p.Gly258Cys c.772G>T in exon 7), one nonsense mutation (p.Ser383Ter c.1148C>A in exon 9), the splice site variant c.1253+1G>T in intron 9, and the deletion of 12 nucleotides in exon 10 (p.Ser433_Ile436del c.1298_1309del12). Our study indicates that mutations in the GCK/MODY2 gene are a very common cause of MODY in the Italian population and broadens our knowledge of the naturally occurring GCK mutation repertoire.     

Mutational analysis of mucopolysaccharidosis type VI patients undergoing a phase II trial of enzyme replacement therapy

Mucopolysaccharidosis type VI (MPS VI; Maroteaux-Lamy syndrome) is a lysosomal storage disorder caused by mutations in the N-acetylgalactosamine-4-sulfatase (ARSB) gene. These mutations result in a deficiency of ARSB activity. Ten MPS VI patients were involved in a phase II clinical study of enzyme replacement therapy. Direct sequencing of genomic DNA from these patients was used to identify ARSB mutations. Each individual exon of the ARSB gene was amplified by PCR and subsequently sequenced. Thirteen substitutions (c.215T>G [p.L72R] c.284G>A [p.R95Q], c.305G>A [p.R102H], c.323G>T [p.G108V], c.389C>T [p.P130L], c.511G>A [p.G171S], c.904G>A [p.G302R], c.944G>A [p.R315Q], c.1057T>C [p.W353R], c.1151G>A [p.S384N], c.1178A>C [p.H393P], c.1289A>G [p.H430R] and c.1336G>C [p.G446R]), one deletion (c.238delG), and two intronic mutations (c.1213+5G>A and c.1214-2A>G) were identified. Nine of the 16 mutations identified were novel (R102H, G108V, P130L, G171S, W353R, H430R, G446R, c.1213+5G>A and c.1214-2A>G). The two common polymorphisms c.1072G>A [p.V358M] and c.1126G>A [p.V376M] were identified in some of the patients, along with the silent mutations c.972A>G and c.1191A>G. Cultured fibroblast ARSB mutant protein and residual activity were determined for each patient and, together with genotype information, used to predict the expected clinical severity of each patient.     

Identification of novel MLC1 mutations in Chinese patients with megalencephalic leukoencephalopathy with subcortical cysts (MLC)

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is an autosomal, recessively inherited disease caused by mutations in the MLC1 gene. Most of the previously published studies have been carried out in ethnic populations other than the Chinese. In this study, the analysis of clinical features and MLC1 mutation screening were performed in 13 Chinese patients for the first time. A total of 10 MLC1 mutations were identified in these patients, including five novel missense mutations (c.65G>A, p.R22Q; c.95C>T, p.A32V; c.218G>A, p.G73E; c.823G>A, p.A275T; c.832T>C, p.Y278H), one novel splicing mutation (c.772-1G>C in IVS9-1), one novel small deletion (c.907_930del, p.V303_L310del), one known nonsense mutation (c.593delCTCA, p.Y198X) and two known missense mutations (c.206C>T, p.S69L; c.353C>T, p.T118M). Mutation c.772-1G>C in IVS9-1, accounting for 27.3% (3/11) of the total number of genetically confirmed patients found in this study, is thus a putative hot-spot mutation in the present study group. The existence of a unique MLC1 mutation spectrum in Chinese MLC patients was shown. A systemic study to assess the mutation spectra in different populations should be undertaken.     

Liver glycogen storage diseases due to phosphorylase system deficiencies: diagnosis thanks to non invasive blood enzymatic and molecular studies

Glycogen storage disease (GSD) due to a deficient hepatic phosphorylase system defines a genetically heterogeneous group of disorders that mainly manifests in children. We investigated 45 unrelated children in whom a liver GSD VI or IX was suspected on the basis of clinical symptoms including hepatomegaly, increased serum transaminases, postprandial lactatemia and/or mild fasting hypoglycemia. Liver phosphorylase and phosphorylase b kinase activities studied in peripheral blood cells allowed to suspect diagnosis in 37 cases but was uninformative in 5. Sequencing of liver phosphorylase genes was useful to establish an accurate diagnosis. Causative mutations were found either in the PYGL (11 patients), PHKA2 (26 patients), PHKG2 (three patients) or in the PHKB (three patients) genes. Eleven novel disease causative mutations, five missense (p.N188K, p.D228Y, p.P382L, p.R491H, p.L500R) and six truncating mutations (c.501_502ins361pb, c.528+2T>C, c.856-29_c.1518+614del, c.1620+1G>C, p.E703del and c.2313-1G>T) were identified in the PYGL gene. Seventeen novel disease causative mutations, ten missense (p.A42P, p.Q95R, p.G131D, p.G131V, p.Q134R, p.G187R, p.G300V, p.G300A, p.C326Y, p.W820G) and seven truncating (c.537+5G>A, p.G396DfsX28, p.Q404X, p.N653X, p.L855PfsX87, and two large deletions) were identified in the PHKA2 gene. Four novel truncating mutations (p.R168X, p.Q287X, p.I268PfsX12 and c.272-1G>C) were identified in the PHKG2 gene and three (c.573_577del, p.R364X, c.2427+3A>G) in the PHKB gene. Patients with PHKG2 mutations evolved towards cirrhosis. Molecular analysis of GSD VI or IX genes allows to confirm diagnosis suspected on the basis of enzymatic analysis and to establish diagnosis and avoid liver biopsy when enzymatic studies are not informative in blood cells.     

Kallmann syndrome: 14 novel mutations in KAL1 and FGFR1 (KAL2)

Kallmann syndrome (KAL) combines hypogonadotropic hypogonadism and anosmia. Hypogonadism is due to Gonadotropin Releasing Hormone (GnRH) deficiency and anosmia is related to hypoplasia of the olfactory bulbs. Occasional symptoms include renal agenesis, bimanual synkinesia, cleft lip palate, dental agenesis. KAL is genetically heterogeneous and two genes have so far been identified, namely KAL1 (Xp22.3) and FGFR1/KAL2 (8p12), which underlie the X chromosome‐linked form and an autosomal dominant form of the disease, respectively. We studied a cohort of 98 unrelated Caucasian KAL patients. We identified KAL1 mutations in 14 patients, of which 7 (c.3G>A (p.M1?), g.IVS1+1G>T, c.570_571insA (p.R191fsX14), c.784G>C (p.R262P), c.958G>T (p.E320X), c.1651_1654delinsAGCT (p.P551_E552delinsSX), c.1711T>A (p.W571R)) have not been previously reported. In addition, we found FGFR1 mutations in 7 patients, namely c.303G>A (p.V102I), C.385A>C (p.D129A), c.810G>A (p.V273M), c.1093_1094delAG (p.R365fsX41), c.1561G>A (p.A520T), c.1836_1837insT (p.Y613fsX42), c.2190C>G (p.Y730X), all of which were novel mutations. In this study, unilateral renal agenesis and bimanual synkinesia were exclusively found associated with KAL1mutations, cleft palate and dental agenesia with FGFR1mutations. © 2004 Wiley‐Liss, Inc.     

Splice-site contribution in alternative splicing of PLP1 and DM20: molecular studies in oligodendrocytes

Mutations in the proteolipid protein 1 (PLP1) gene cause the X-linked dysmyelinating diseases Pelizaeus-Merzbacher disease (PMD) and spastic paraplegia 2 (SPG2). We examined the severity of the following mutations that were suspected of affecting levels of PLP1 and DM20 RNA, the alternatively spliced products of PLP1: c.453G>A, c.453G>T, c.453G>C, c.453+2T>C, c.453+4A>G, c.347C>A, and c.453+28_+46del (the old nomenclature did not include the methionine codon: G450A, G450T, G450C, IVS3+2T>C, IVS3+4A>G, C344A, and IVS3+28-+46del). These mutations were evaluated by information theory-based analysis and compared with mRNA expression of the alternatively spliced products. The results are discussed relative to the clinical severity of disease. We conclude that the observed PLP1 and DM20 splicing patterns correlated well with predictions of information theory-based analysis, and that the relative strength of the PLP1 and DM20 donor splice sites plays an important role in PLP1 alternative splicing.     

Functional analysis of 13 GBA mutant alleles identified in Gaucher disease patients: Pathogenic changes and "modifier" polymorphisms

Gaucher disease, the most prevalent sphingolipidosis, is caused by the deficient activity of acid beta-glucosidase, mainly due to mutations in the GBA gene. Over 200 mutations have been identified worldwide, more than 25 of which were in Spanish patients. In order to demonstrate causality for Gaucher disease, some of them: c.662C>T (p.P182L), c.680A>G (p.N188S), c.886C>T (p.R257X), c.1054T>C (p.Y313H), c.1093G>A (p.E326K), c.1289C>T (p.P391L), c.1292A>T (p.N392I), c.1322T>C (p.I402T), and the double mutants [c.680A>G; c.1093G>A] ([p.N188S; p.E326K]) and [c.1448T>C; c.1093G>A] ([p.L444P; p.E326K]), were expressed in Sf9 cells using a baculovirus expression system. Other well-established Gaucher disease mutations, namely c.1226A>G (p.N370S), c.1342G>C (p.D409H), and c.1448T>C (p.L444P), were also expressed for comparison. The levels of residual acid beta-glucosidase activity of the mutant enzymes produced by the cDNAs carrying alleles c.662C>T (p.P182L), c.886C>T (p.R257X), c.1054T>C (p.Y313H), c.1289C>T (p.P391L), and c.1292A>T (p.N392I) were negligible. The c.1226A>G (p.N370S), c.1322T>C (p.I402T), c.1342G>C (p.D409H), c.1448T>C (p.L444P), and [c.1448T>C; c.1093G>A] ([p.L444P; p.E326K]) alleles produced enzymes with levels ranging from 6 to 14% of the wild-type. The three remaining alleles, c.680A>G (p.N188S), c.1093G>A (p.E326K), and [c.680A>G; c.1093G>A] ([p.N188S; p.E326K]), showed higher activity (66.6, 42.7, and 23.2%, respectively). Expression studies revealed that the c.1093G>A (p.E326K) change, which was never found alone in a Gaucher disease-causing allele, when found in a double mutant such as [c.680A>G; c.1093G>A] ([p.N188S; p.E326K]) and [c.1448T>C; c.1093G>A] ([p.L444P; p.E326K]), decreases activity compared to the activity found for the other mutation alone. These results suggest that c.1093G>A (p.E326K) should be considered a "modifier variant" rather than a neutral polymorphism, as previously considered. Mutation c.680A>G (p.N188S), which produces a mutant enzyme with the highest level of activity, is probably a very mild mutation or another "modifier variant."     

Novel MC1R variants in Ligurian melanoma patients and controls

Several variant forms of the melanocortin-1 receptor gene (MC1R) have been associated with red hair, fair skin and an increased risk for melanoma. Their involvement in melanoma susceptibility is apparently linked both to skin sensitivity and to non-pigmentary pathways. We investigated the frequency of the MC1R variants in the Italian region of Liguria, where the occurrence and penetrance of melanoma are low and primary susceptibility is characterized by prevalence of the CDKN2A c.301G>T [p.G101W] founder mutation. Additionally, we attempted to establish the frequency of the red hair/fair skin phenotype in our region. As predicted by anecdotal evidence, the frequency of red hair/phototype I was very low (0.7%). Screening of 17 red-haired individuals and their red-haired relatives, 207 controls and 214 melanoma patients unselected for hair color but all of Ligurian descent, led to the detection of 8 novel substitutions (c.133T>C [p.F45L], c.248C>T [p.S83L], c.332C>T [p. A111V], c.479G>A [p.R160Q], c.637C>T [p.R213W], c.793G>A [p. V265I], c.923C>T [p. T308M], c.943T>C [p.C315R]), 1 novel deletion (c.520_523delGTC [p.V174del]) and 3 novel synonymous variants (c.366G>C [p. V122V], c.684G>A [p. Q228Q], c.726C>T [p.T241T]). Preliminary genotype/phenotype correlation seems to indicate that other genes involved in the regulation of human pigmentation may mask the recessive action of high-penetrance MC1R alleles, thus determining the low frequency of at-risk phototypes and of incidence and/or penetrance of melanoma in Liguria.     

Functional assays testing pathogenicity of 14 cystathionine-beta synthase mutations

In this study, 14 CBS alleles from homocystinuric patients were expressed heterologously in E. coli and their enzyme activities were assayed in vitro. Additionally, mutant CBS proteins were visualized by Western blot from denaturing and non-denaturing polyacrylamide gels. The 14 mutations characterized were: p.R125W (c.373C>T), p.G148R (c.442G>A), p.M173V (c.517A>G), p.T191M (c.572C>T), p.A226T (c.676G>A), p.C275Y (c.824G>A), p.R336C (c.1006C>T), p.R336H (c.1007G>A), p.L338P (c.1013T>C), p.S349N (c.1046G>A), p.R379Q (c.1136G>A), p.L456P (c.1367T>C), p.G522fsX540 (c.1566delG), and p.R548Q (c.1643G>A). Eleven of the mutant alleles exhibited an activity lower than 4% of the wild-type protein. In contrast, mutations p.A226T and p.M173V presented 20% and 40% of the wild-type activity, respectively, whereas the activity of p.R548Q was up to 60% of the wild-type. This suggests that it is a new rare variant rather than a pathogenic mutation. Most of the mutated proteins exhibited a decreased signal in Western blot analyses. The non-denaturing PAGE revealed that the wild-type protein retained the capacity to form a multimeric quaternary structure, whereas in the mutations p.M173V, p.A226T, and p.G548Q, this structure grade was dramatically reduced and was completely absent in the rest of the mutations.     

Identification and characterization of five novel MAN2B1 mutations in Italian patients with alpha-mannosidosis

Mutation analysis performed on six Italian families with alpha-mannosidosis type II allowed the identification of five new mutations in the MAN2B1 gene: c.157G>T, c.562C>T, c.599A>T, c.293dupA, c.2402G>A (p.E53X, p.R188X, p.H200L, p.Y99VfsX61, p.G801D). Protein residues G801 and H200 are conserved among the four mammalian alpha-mannosidases cloned to date: human, cattle, cat and mouse. In vitro expression studies demonstrated that both missense mutations expressed no residual alpha-mannosidase activity indicating that they are disease-causing mutations. Modelling into the three-dimensional structure revealed that the p.H200L could involve the catalytic mechanism, whereas p.G801D would affect the correct folding of the enzyme.     

五个Dysferlinopathy家系的 DYSF基因变异分析

目的:对5个Dysferlinopathy家系进行 DYSF基因变异分析,明确其致病原因。 方法:应用高通量测序技术进行检测,确定可疑变异后应用Sanger测序进行变异位点验证,根据美国医学遗传学及基因组学学会(American College of Medical Genetics and Ge...     

Clinical characteristics and molecular analysis of 21 Chinese children with congenital agammaglobulinemia

Congenital agammaglobulinemia is a humoral primary immunodeficiency and affected patients have extremely low levels of peripheral B cells and profound deficiency of all immunoglobulin isotypes. Mutations of the Bruton's tyrosine kinase (BTK) gene are responsible for most of the congenital agammaglobulinemia. In this study, the phenotypes of congenital agammaglobulinemia were investigated in 21 male children from 21 unrelated Chinese families. Sixteen different mutations of BTK gene were identified in 18 patients, and three patients did not have BTK gene mutations. Nine mutations had been reported previously including one gross deletion (c.722_2041del), one missense mutation (c.1764G>T), three non-sense mutations (c.194C>A, c.895C>T and c.1821G>A) and four invariant splice-site mutations (c.971+2T>C, c.1481+2T>A, c.1482-2A>G, c.1699-2A>G). Seven novel mutations were identified (c.373_441del, c. 504delG, c.537delC, c.851delA, c.1637G>A, c.1879T>C and c. 1482_1882 del). Ten of the eighteen mutations of BTK gene were located in the TK domain, four in the PH domain, three in the SH3 domain and one spanned the TH, SH3, SH2 and TK domain. Candidate genes of autosomal-recessive agammaglobulinemia, including IGHM, CD79a, CD79b and IGLL1, were screened in three patients without mutations in the BTK gene. A compound heterozygosity mutation in the IGHM gene (c.1956G>A, c.175_176insC) was identified in one patient. The results of our study further support that molecular genetic testing represents an important tool for early confirmed diagnosis of congenital agammaglobulinemia and may allow accurate carrier detection and prenatal diagnosis.     

Twelve novel JAG1 gene mutations in Polish Alagille syndrome patients

Alagille syndrome (AGS) is an autosomal dominant disorder with developmental abnormalities of the liver, heart, eyes, vertebrae, and face. Mutations in the JAG1 (Jagged 1) gene, coding a ligand in the evolutionarily conserved Notch signaling pathway, are responsible for AGS. Here we present sixteen different JAG1 gene mutations, among them twelve novel, not described previously. Seven frameshift: c. 172_178del7 (p.Ala58fs), c.509delT (p.Leu170fs), c.1197delG (p.Val399fs), c.1485_1486delCT (p.Pro495fs), c.1809_1810insTGGG (p.Lys604fs), c.2122_2125delCAGT (p.Gln708fs), c.2753delT (p.Ile918fs); five nonsense: c.383G>A (p.Trp128X), c.496C>T (p.Glu166X), c.841C>T (p.Gln281X), c.1207C>T (p.Gln403X), c.1603C>T (p.Gln535X); two splice site: c.388-1G>C, c.3048+1_3048+2insG and two missense mutations: c.359T>A (p.Ile120Asn), c.560G>A (p.Cys187Tyr) were found. Forty percent of the changes were identified in exons 2 and 4, the remaining mutations are distributed along the entire coding sequence of the gene. Seventy-five percent of the mutations lead to creation of premature termination codons. Family studies revealed that the specific mutations were inherited in 3 out of 11 investigated cases. No correlation between genotype and phenotype was observed.