Analysis of the low density lipoprotein receptor gene (LDLR) mutation spectrum in Russian familial hypercholesterolemia.

Familial hypercholesterolemia (FH) is a very common human hereditary disease in Russia and in the whole world with most of mutations localized in the gene coding for the low density lipoprotein receptor (LDLR). The object of this review is to systematize the knowledge about LDLR mutations in Russia. With this aim we analyzed all available literature on the subject and tabulated the data. More than 1/3 (80 out of 203, i. e. 39.4 %) of all mutations reported from Russia were not described in other populations. To date, most LDLR gene mutations have been characterized in large cities: Moscow (130 entries), Saint Petersburg (50 entries), Novosibirsk (34 mutations) and Petrozavodsk (19 mutations). Other regions are poorly studied. The majority of pathogenic mutations (142 out of 203 reported here or 70 %) were revealed in single pedigrees; 61 variants of mutations were described in two or more genealogies; only 5 mutations were found in 10 or more families. As everywhere, missense mutations prevail among all types of nucleotide substitutions in LDLR, but the highest national specificity is imparted by frameshift mutations: out of 27 variants reported, 19 (or 70 %) are specific for Russia. The most abundant in mutations are exons 4 and 9 of the gene due to their largest size and higher occurrence of mutations in them. Poland,the Czech Republic, Italy and the Netherlands share the highest number of mutations with the Russian population. Target sequencing significantly accelerates the characterization of mutation spectra in FH, but due to the absence of systematic investigations in the regions, one may suggest that most of LDLR mutations in the Russian population have not been described yet.

[Distribution in early mouse embryos of foreign mtDNA transmitted along the paternal lineage].

Transmission of foreign mtDNA along the paternal lineage founded by male mice (F0), and distribution of that mtDNA in their progeny at early stages of prenatal development were studied. Transmitochondrial males of F0 obtained after injection of human mitochondria into mouse zygotes has been shown to transmit foreign mtDNA to subsequent generations. Individual peculiarities among the males studied, concerning transmission of foreign mtDNA to the progeny, are likely to exist. Besides, the distribution of human mtDNA among blastomeres of transmitochondrial embryos under study differed from that observed in previous investogation of its inheritance along the maternal lineage.

"Finnish" mutations in LDL receptor gene: a rare cause of familial hypercholesterolemia in St. Petersburg and Petrozavodsk.

The search for two mutations, FH-Helsinki and FH-North Karelia, in LDL receptor gene was carried out in patients with familial hypercholesterolemia from St. Petersburg (80 families) and Petrozavodsk (80 families) using allele-specific PCR and analysis of single-stranded DNA fragment conformation polymorphism (SSCP analysis) with subsequent sequencing. The FH-North Karelia mutation was found in one family in St. Petersburg and in one family in Petrozavodsk, while FH-Helsinki mutation was not detected in any of the samples. Hence, the two "Finnish" mutations together responsible for 2/3 familial hypercholesterolemia cases in Finland were extremely rare in the Russian regions neighboring Finland.

[New mutations in low-density lipoprotein receptor gene in familial hypercholesterolemia patients from Petrozavodsk].

Using an automated fluorescent single-strand conformation polymorphism (SSCP) analysis of the entire coding region, promoter zone, and exon-intron junctions of the low-density lipoprotein (LDL) receptor gene, we examined 80 DNA samples of patients with familial hypercholesterolemia (FH) from Petrozavodsk. We revealed mutations that might cause FH in five probands, including FH-North Karelia (c.925-931del7) mutation and four previously unknown mutations. These novel mutations included a transversion (c.618T>G (p.S206R), one nucleotide insertion c.195_196insT (p.FsV66:D129X), a complex gene rearrangement c.192del10/ins8 (p.FsS65:D129X), and a single nucleotide deletion c.2191delG (p.FsV731:V736X). Three out of four novel mutations produce an open reading frame shift and the premature termination of translation. An analysis of the cDNA sequence of the LDL receptor showed that this might result in the formation of a transmembrane-domain-deficient receptor that is unable to bind and internalize the ligand. Our results suggest the absence of a strong founder effect associated with FH in the Petrozavodsk population.

[Distribution of foreign mitochondrial DNA during the first splittings of the transmitochondrial mouse embryos].

Distribution of human mitochondrial DNA (mtDNA) among separate murine blastomeres was analyzed during the splitting of embryos in which the suspension of human mitochondria had been injected at the one- or two-cell stage. Human mtDNA was detected by PCR with species specific primers. The total amount of the two- and four-cell murine embryos analyzed in the study was 339. In all embryos examined the copies of human mitochondrial genome were revealed along with murine mtDNA, which indicated the phenomenon of an artificially modeled heteroplasmy. The foreign mtDNA was not ubiquitous among the blastomeres of transmitochondrial embryos. Mathematical analysis of the results showed that in the period between the injection of human mitochondria and the subsequent splitting no equal distribution of the human mtDNA occurred in the cytoplasm. These results also point at the presence of more than 2-3 segregation units of mtDNA in the entire pool of mitochondria (about 5 x 10(2)) introduced into an embryo by microinjection.

[Familial hypercholesterolemia in St. Petersburg: diversity of mutations argues against a strong founder effect].

Examination of low-density lipoprotein (LDL) receptor, its promoter, and major exon-intron boundaries from a sample of patients with familial hypercholesterolemia (FH) from 74 probands of St. Petersburg revealed 34 mutations and 8 widely spread polymorphisms at this locus. Only four mutations were considered silent, while the other 30 are likely associated with familial hypercholesterolemia (FH). Mutations in the LDL receptor gene, inducing the disease, were identified in 41 (55%) out of 74 families with FH. Mutation R3500Q in apolipoprotein B (APOB) gene was not detected in all probands. Therefore in the families lacking mutations hypercholesterolemia was induced by mutations in the introns of the LDL receptor gene or by other genetic factors. Nineteen mutations causing disease progression were described in St. Petersburg for the first time, while 18 of them are specific for Russia. Among Ashkenazi Jews, major mutation G197del was detected in 30% (7 out of 22) of patients with FH. In the Slavic population of St. Petersburg, no major mutations were detected. Only five mutations were identified in two families, while 24 were found in isolated families. These data are indicative of the lack of a strong founder effect for FH in the St. Petersburg population.

[Mutations and polymorphisms in the genes for myocilin and optineur in as the risk factors of primary open-angle glaucoma].

A collection of DNA samples obtained from primary open-angle glaucoma (POAG) patients from St. Petersburg was analyzed for single-strand conformation polymorphism (SSCP) to reveal sequence variants in exon 3 of the myocilin gene (MYOC/TIGR) and in exons 4 and 5 of the optineurin gene (OPTN), where most of the mutations revealed worldwide are located. The Q368X mutation (c. 1102 C --> T) in exon 3 of MYOC/TIGR was detected in 1.2% (2/170) of the POAG patients from St. Petersburg, i.e., with the frequency close to that observed in other world populations. Three known polymorphisms in exon 3 of MYOC/TIGR, Y347Y (c. 1041 T --> C) (12.4%), T325T (c. 975 G --> A) (0.6%), and K398R (c. 1193 A --> G) (0.6%) were also detected. No statistically significant differences in frequencies of these polymorphisms were revealed between the POAG patient and control groups. The L41L polymorphism (c. 433 G --> A) in exon 4 of OPTN was detected in 2.9% of probands and in 1% of controls. The frequency of heterozygotes for the M98K polymorphism (c. 603 T --> A) in the OPTN exon 5 was statistically significantly higher (P = 0.036; Fisher's exact test) among the POAG patients (6.5%) than among the controls (1%). In the sample examined the E50K mutation, typical of the patients with pseudonormal intraocular pressure glaucoma, was not found.

[Identification of novel missense mutation G571E, novel silent mutation H229H, nonsense mutation C74X, and four single nucleotide polymorphisms in the low-density lipoprotein receptor in patients with familial hypercholesterolemia from St. Petersburg]. / Identifikatsiia novoi missens-mutatsii G571E, novoi molchashchei mutatsii H229H, nonsens-mutatsii C74X i chetyrekh odnonukleotidnykh polimorfizmov v gene retsptora lipoproteinov nizkoi plotnosti u patsientov s semeinoi giperkholesterinemiei Sankt-Peterburga.

Novel missense mutation G571E (c.1775 G > A), novel silent mutation H229H (c.750 C > T), and nonsense mutation C74X (c.285 C > A), earlier described in Japan but unknown in Russia, were identified in the low-density lipoprotein (LDL) receptor gene in St. Petersburg familial hypercholesterolemia in patients. The analyzed group of patients was shown to be polymorphic in many positions of the LDL receptor gene, namely: c.1171 G/A, c.1773 T/C, c.2177 C/T, and c.2231 G/A.

Two novel low-density lipoprotein receptor gene mutations (E397X and 347delGCC) in St. Petersburg familial hypercholesterolemia.

Familial hypercholesterolemia (FH), a monogenic disease known to be caused by low-density lipoprotein receptor (LDLR) gene mutations, results in the development of premature atherosclerosis and coronary artery disease in affected individuals. The spectrum of LDLR gene mutations in Russia is poorly known. Using polymerase chain reaction (PCR)-single-strand conformational polymorphism (SSCP) analysis, followed by DNA sequencing, we have screened selected exons of the LDLR gene in 80 unrelated St. Petersburg FH patients for the presence of mutations. Two new LDLR gene mutations, 347delGCC and E397X, were characterized among individuals with familial hypercholesterolemia in St. Petersburg. The carriers of both mutations possessed highly elevated blood serum cholesterol. Cosegregation of E397X mutation and LDLR gene RFLP haplotypes with hyperlipidemia was demonstrated by family study. Both mutations seem to be specific to Slavic patients.