BARTH SYNDROME IN MALE AND FEMALE SIBLINGS CAUSED BY A NOVEL MUTATION IN THE TAZ GENE.

Barth syndrome (BTHS) is an X-linked recessive disease caused by mutations in tafazzin gene (TAZ) which lead to cardiolipin deficiency and mitochondrial dysfunction. Male patients have variable clinical findings, including cardiomyopathy, skeletal myopathy, prepubertal short stature, neutropenia and 3-methylglutaconic aciduria. Female carriers are usually asymptomatic. We report a novel TAZ gene mutation in male and female siblings with left ventricular noncompaction and hypotonia. Additionally, the brother presented an intermittent neutropenia and increased urinary levels of 3-methylglutaconic and 3-methylglutaric acid. The molecular genetic testing showed that both siblings carry the mutation: c.253insC, p.(Arg85Profs*54) in exon 3 of the TAZ gene. This article presents the first case of BTHS in a heterozygous female patient with normal karyotype.

A family with fragile X syndrome, Duchenne muscular dystrophy and ichthyosis transmitted by an asymptomatic carrier.

The human X chromosome carries regions prone to genomic instability: deletions in the Xp22.31 region, involving the steroid sulfatase gene (STS) cause X-linked ichthyosis; rearrangements in the Xp21.2 region are associated with Duchenne or Becker muscular dystrophies (DMD or BMD); and the Xq27.3 unstable region, containing the (CGG)n repeat expansion in the FMR1 gene is associated with fragile X syndrome. We report on a family with two affected boys, the elder diagnosed with fragile X syndrome, the younger with DMD, and both suffering from severe ichthyosis. The family was analyzed by polymerase chain reaction, multiplex ligation-dependent probe amplification and haplotype analysis. The mother proved to be an asymptomatic carrier of all three non-contiguous mutation events, involving the STS gene, the DMD gene and a FMR1 expansion. To the best of our knowledge, this is the first description of an asymptomatic carrier of three different X-linked disorders, involving severe genetic rearrangements on both long and short arms of the X chromosomes. The boy with fragile X syndrome has inherited a triple recombinant maternal X chromosome, this way inheriting the FMR1 expansion and ichthyosis, originating most probably from different maternal Xes and excluding the DMD gene deletion. The transmission of these extremely defective maternal chromosomes to the next generation involved several recombinations.

First Bulgarian case of citrin deficiency caused by one novel and one recurrent mutation in the SLC25A13 gene.

Citrin deficiency is an autosomal recessive disorder caused by mutations in the SLC25A13 gene and has three phenotypes: neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) in newborns, failure to thrive and dyslipidemia caused by citrin deficiency (FTTDCD) in older children, and recurrent hyperammonemia with neuropsychiatric symptoms in citrullinemia type II (CTLN2) in adults. NICCD presents in the first few weeks of life with cholestatic hepatitis syndrome, multiple aminoacidemia and hypergalactosemia. To date almost all reported patients were from East Asia and only few cases from Caucasian origin have been described. We report the first Bulgarian case of NICCD. Mutation screening of the SLC25A13 gene revealed the compound heterozygous mutations c.1081C>T (p.R361*) and c.74C>A (p. A25E) which confirmed the diagnosis of NICCD. The nonsense mutation c.1081C>T (p.R361*) is novel.

Analysis of the genes encoding neuroligins NLGN3 and NLGN4 in Bulgarian patients with autism.

Many studies have supported a genetic aetiology for autism. Neuroligins are postsynaptically located cell-adhesion molecules. Mutations in two X-linked neuroligin genes, NLGN3 and NLGN4, have been implicated in pathogenesis of autism. In order to confirm these causative mutations in our autistic population and to determine their frequency we screened 20 individuals affected with autism. We identified one patient with a point mutation in NLGN4 gene that substituted a Met for Thr 787 - c.2360C > T, p.(Thr787Met) and three patients with identical polymorphisms in the same gene: c.933C > T, p.(Thr311Thr) in combination with c.[1777C > T+1779C > G, p.(Leu593Leu)]. All patients tested for NLGN3 mutations were negative. These results indicate that mutations in these genes are responsible for at most a small fraction of autism cases.

Mitochondrial DNA mutations in two bulgarian children with autistic spectrum disorders.

Autism is a neurodevelopmental disorder of unknown origin that manifests in early childhood. Autism spectrum disorders (ASDs) refer to a broader group of neurobiological conditions, pervasive developmental disorders. Despite several arguments for a strong genetic contribution, the molecular basis in most cases remains unexplained. Several studies have reported an association between ASDs and mutations in the mitochondrial DNA (mtDNA) molecule. In order to confirm these causative relationship, we screened 21 individuals with idiopathic ASDs for a number of the most common mtDNA mutations. We identified two patients with candidate mutations: m.6852G>A that produces an amino acid change of glycine to serine in the MT-CO1 gene and m.8033A>G (Ile→Val) in the MT-CO2 gene. Overall, these findings support the notion that mitochondrial mutations are associated with ASDs. Additional studies are needed to further define the role of mitochondrial defects in the pathogenesis of autism.

Mortality and cause of death in mucopolysaccharidosis type II-a historical review based on data from the Hunter Outcome Survey (HOS).

Mucopolysaccharidosis type II (MPS II or Hunter syndrome) is a progressive, multisystemic disease caused by a deficiency of iduronate-2-sulfatase. Patients with the severe form of the disease have cognitive impairment and typically die in the second decade of life. Patients with the less severe form do not experience significant cognitive involvement and may survive until the fifth or sixth decade of life. We studied the relationship of both severity of MPS II and the time period in which patients died with age at death in 129 patients for whom data were entered retrospectively into HOS (Hunter Outcome Survey), the only large-scale, multinational observational study of patients with MPS II. Median age at death was significantly lower in patients with cognitive involvement compared with those without cognitive involvement (11.7 versus 14.1 years; p = 0.024). These data indicate that cognitive involvement is indicative of more severe disease and lower life expectancy in patients with MPS II. Median age at death was significantly lower in patients who died in or before 1985 compared with those who died after 1985 (11.3 versus 14.1 years; p alpha 0.001). The difference in age at death between patients dying in or before, relative to after, the selected cut-off date of 1985 may reflect improvements in patient identification, care and management over the past two decades. Data from patients who died after 1985 could serve as a control in analyses of the effects of enzyme replacement therapy with idursulfase on mortality in patients with MPS II.

[Second trimester Down syndrome serum screening--results from a pilot study]. / Serumen skrining za sindrom na Daun vuv vtori trimestur na bremennostta--rezultati ot pilotno prouchvane.

The results from a pilot prospective study--second trimester Down syndrome [DS] serum screening between 15 and 21 w.g. with two markers (alpha-fetoprotein and free bb-hCG)--were summarised. Sensitivity, false-positive rate [FPR], positive predictive value [PPV] of the screen positive and negative predictive value [NPV] of the screen negative result for the sbgroups II and below 35 years of age were analysed. The uptake for invasive prenatal testing in screen positive patients and the percentage of terminated pregnancies with prenatally diagnosed DS fetuses as well as the ratio "lost unaffected pregnancies/1 DS fetus diagnosed antenatally" were also calculated. High sensitivity of the DS serum screening was achieved--75% and 87.5% in the subgroups below and II the age of 35 respectively with 6.6 and 31.7% FPR. With higher DS age risk the PPV of the screen positive test was higher and the NPV of the screen negative result--lower. The percentage of invasive prenatal testing in screen positive patients was high (average 83.4%) without significant differences in the two age subgroups. Pregnancy was terminated in all cases with antenatally diagnosed DS fetuses. The ratio "lost unaffected pregnancies/1 DS fetus diagnosed antenatally" for serum screening was lower compared to the same ratio when screening by age. The results from our pilot study (serum screening sensitivity and FPR, uptake for invasive testing in screen-positive cases) are comparable to the ones reported in literature. This is an important prerequisite for introduction of mass DS screening for our population.

Hunter syndrome (Muccopolysaccharridosis Type II) in Macedonia and Bulgaria.

BACKGROUND: Mucopolysaccharidosis II (MPS II) is caused by a deficiency of iduronate-2-sulfatase (IDS; EC 3.1.6.13). METHODS AND RESULTS: We describe 11 boys from Bulgaria and Macedonia detected in the period from 1998 to 2008. The mean age at diagnosis was 4.77+/-1.29 years. All children were severely retarded: IQ ranged from 34-80, and they all had coarse faces and hepatomegaly. In addition, splenomegaly was found in 81.81% patients, dysostosis in 45.45%, kyphosis in 27.27%, deafness in 18.08%, growth below the third percentile in 45.45%, growth below the parental target height in all patients, stiff joints in 56.56% and hypertrophic myocardiopathy in 18.18% children. Two patients died at the age of 11 and 35 years. Plasma iduronate-2-sulfatase was low in all probands and normal in parents and relatives. Two new mutations were discovered: p.K236N (c.708G>C) in a child with a moderately severe phenotype, and p.Q80K (c.238C>A) which resulted in a severe phenotype and early death at the age of 11 years. Heterozygote carriers of the pathogenic allele were 29 female relatives. The calculated incidence rate for MPS II in Macedonia (censuses 1994 and 2002, children under 14 years: 483,923 and 426,280) and Bulgaria (censuses 1992 and 2006, children under 14 years: 1 126, 598 and 1,077,020) are 0.36 and 0.46 respectively, while the calculated prevalence rate are 3.6 and 4.6 per 1,000,000 boys (aged 0-14 years). Correlating phenotype and genotype remains a complex endeavour. CONCLUSIONS: We report calculated incidence and prevalence rates in two South Eastern European countries, and 2 novel genetic alterations correlated with their phenotypes.

Prenatal diagnosis of severe structural congenital malformations in Europe.

OBJECTIVES: To assess at a population-based level the frequency with which severe structural congenital malformations are detected prenatally in Europe and the gestational age at detection, and to describe regional variation in these indicators. METHODS: In the period 1995-1999, data were obtained from 17 European population-based registries of congenital malformations (EUROCAT). Included were all live births, fetal deaths and terminations of pregnancy diagnosed with one or more of the following malformations: anencephalus, encephalocele, spina bifida, hydrocephalus, transposition of great arteries, hypoplastic left heart, limb reduction defect, bilateral renal agenesis, diaphragmatic hernia, omphalocele and gastroschisis. RESULTS: The 17 registries reported 4366 cases diagnosed with the 11 severe structural malformations and of these 2300 were live births (53%), 181 were fetal deaths (4%) and 1863 were terminations of pregnancy (43%); in 22 cases pregnancy outcome was unknown. The overall prenatal detection rate was 64% (range, 25-88% across regions). The proportion of terminations of pregnancy varied between regions from 15% to 59% of all cases. Gestational age at discovery for prenatally diagnosed cases was less than 24 weeks for 68% (range, 36-88%) of cases. There was a significant relationship between high prenatal detection rate and early diagnosis (P < 0.0001). For individual malformations, the prenatal detection rate was highest for anencephalus (469/498, 94%) and lowest for transposition of the great arteries (89/324, 27%). Termination of pregnancy was performed in more than half of the prenatally diagnosed cases, except for those with transposition of the great arteries, diaphragmatic hernia and gastroschisis, in which 30-40% of the pregnancies with a prenatal diagnosis were terminated. CONCLUSION: European countries currently vary widely in the provision and uptake of prenatal screening and its quality, as well as the "culture" in terms of decision to continue the pregnancy. This inevitably contributes to variation between countries in perinatal and infant mortality and in childhood prevalence and cost to health services of congenital anomalies.