Abnormal thyroid function is common in takotsubo syndrome and depends on two distinct mechanisms: results of a multicentre observational study.

BACKGROUND: Several reports have described Takotsubo syndrome (TTS) secondary to thyrotoxicosis. A complex interaction of central and peripheral catecholamines with thyroid homeostasis has been suggested. In this study, we analysed sequential thyroid hormone profiles during the acute phase of TTS. METHODS: Thyrotropin (TSH), free T4 (FT4) and free T3 (FT3) concentrations were analysed at predefined time points in 32 patients presenting with TTS or acute coronary syndrome (ACS, n = 16 in each group) in a 2-year period in two German university hospitals. Data were compared to age- and sex-matched controls (10 samples, each of 16 subjects), and an unsupervised machine learning (ML) algorithm identified patterns in the hormone signature. Subjects with thyroid disease and patients receiving amiodarone were excluded from follow-up. RESULTS: Among patients with TTS, FT4 concentrations were significantly higher when compared to controls or ACS. Four subjects (25%) suffered from subclinical or overt thyrotoxicosis. Two additional patients developed subclinical or overt thyrotoxicosis during stay in hospital. In four subjects (25%), FT4 concentrations were increased, despite nonsuppressed TSH concentration, representing an elevated set point of thyroid homeostasis. The thyroid hormone profile was normal in only six patients (38%) presenting with TTS. CONCLUSION: Abnormal thyroid function is frequent in patients with TTS. Primary hyperthyroidism and an elevated set point of thyroid homeostasis are common in TTS, suggesting a stress-dependent endocrine response or type 2 thyroid allostasis. Thyroid function may be a worthwhile target in treating or preventing TTS.

Alpha-thalassemia intellectual disability: variable phenotypic expression among males with a recurrent nonsense mutation - c.109C>T (p.R37X).

Alpha-thalassemia intellectual disability, one of the recognizable X-linked disability syndromes, is characterized by short stature, microcephaly, distinctive facies, hypotonic appearance, cardiac and genital anomalies, and marked skewing of X-inactivation in female carriers. With the advent of next generation sequencing, mutations have been identified that result in less severe phenotypes lacking one or more of these phenotypic manifestations. Here we report five unrelated kindreds in which a c.109C>T (p.R37X) mutation segregates with a variable but overall milder phenotype. The distinctive facial appearance of alpha-thalassemia intellectual disability was present in only one of the 18 affected males evaluated beyond the age of puberty, although suggestive facial appearance was present in several during infancy or early childhood. Although the responsible genetic alteration is a nonsense mutation in exon 2 of ATRX, the phenotype appears to be partially rescued by the production of alternative transcripts and/or other molecular mechanisms.

7q11.23 Microduplication: a recognizable phenotype.

Williams-Beuren syndrome is a well-known microdeletion syndrome with a recognizable clinical phenotype. The subtle phenotype of the reciprocal microduplication of the Williams-Beuren critical region has been described recently. We report seven further patients, and a transmitting parent, with 7q11.23 microduplication. All our patients had speech delay, autistic features and facial dysmorphism consistent with the published literature. We conclude that the presence of specific dysmorphic features, including straight, neat eyebrows, thin lips and a short philtrum, in our patients with speech delay and autistic features provides further evidence that the children with 7q11.23 microduplication have a recognizable phenotype.

10p11.2 to 10q11.2 is a yet unreported region leading to unbalanced chromosomal abnormalities without phenotypic consequences.

Directly transmitted unbalanced chromosomal abnormalities (UBCA) or euchromatic variants (EV) were recently reported for >50 euchromatic regions of almost all human autosomes. UBCA and EV are comprised of a few megabases of DNA, and carriers are in many cases clinically healthy. Here we report on partial trisomies of chromosome 10 within the pericentromeric region which were detected by standard G banding. Those were referred for further delineation of the size of these duplicated regions for molecular cytogenetics and/or array-CGH. Partial trisomies of chromosome 10 in the pericentromeric region were identified prenatally in seven cases. A maximum of three copies of the region from 10p12.1 to 10q11.22 was observed in all cases without apparent clinical abnormalities. The imbalances were either caused by a direct duplication in one familial case or by de novo small supernumerary marker chromosomes (sSMC). Thus, we report a yet unrecognized chromosomal region subject to UBCA detected in seven unrelated cases. To the best of our knowledge, this is the first report of a UBCA in the pericentromeric region of chromosome 10 that is not correlated with any clinical consequences.

Loss of the Y chromosome PAR2 region and additional rearrangements in two familial cases of satellited Y chromosomes: cytogenetic and molecular analysis.

Two cases of rare structural aberrations of the Y chromosome were detected: a del(Y) (q12) chromosome in a child with mild dysmorphic features, obesity and psychomotor delay, and two identical satellited Y chromosomes (Yqs) in a normal twin, which were originally observed during routine prenatal diagnosis. In both cases a Yqs chromosome was detected in the father which had arisen from a reciprocal translocation involving the short arm of chromosome 15 and the heterochromatin of the long arm of the Y chromosome (Yqh). Cytogenetic and molecular studies demonstrated that in the reciprocal product of chromosomes 15 and Y PAR2 could not be detected, showing that PAR2 had been deleted. It is discussed whether the translocation of the short arm of an acrocentric chromosome to the heterochromatin of the long arm of the Y chromosome causes instability of this region which results either in loss of genetic material or interference with the normal mechanism of disjunction.

Complex chromosomal rearrangements.

Complex Chromosomal Rearrangements (CCRs) are constitutional structural rearrangements involving three or more chromosomes or having more than two breakpoints. CCRs preferentially occur during spermatogenesis and are transmitted in families through oogenesis. Recent investigation showed that CCRs are more complex and more common than initially appreciated. Here 1 present an overview of CCRs, including the important impact of CCRs in fertility, the mechanism of their development, the various meiotic errors that can occur and their consequences. The review also discusses the differential transmission of CCRs in males and females, the incidence of pregnancy outcomes of CCR carriers, genetic counseling and prenatal diagnosis.

Measurement of locus copy number by hybridisation with amplifiable probes.

Despite its fundamental importance in genome analysis, it is only recently that systematic approaches have been developed to assess copy number at specific genetic loci, or to examine genomic DNA for submicro-scopic deletions of unknown location. In this report we show that short probes can be recovered and amplified quantitatively following hybridisation to genomic DNA. This simple observation forms the basis of a new approach to determining locus copy number in complex genomes. The power and specificity of multiplex amplifiable probe hybridisation is demonstrated by the simultaneous assessment of copy number at a set of 40 human loci, including detection of deletions causing Duchenne muscular dystrophy and Prader-Willi/Angelman syndromes. Assembly of other probe sets will allow novel, technically simple approaches to a wide variety of genetic analyses, including the potential for extension to high resolution genome-wide screens for deletions and amplifications.

ZNF232: structure and expression analysis of a novel human C(2)H(2) zinc finger gene, member of the SCAN/LeR domain subfamily.

We have identified a novel zinc finger gene, ZNF232, mapped to human chromosome 17p12. The coding region of the gene is organized in three exons corresponding to a 417 amino acid long polypeptide containing a SCAN/LeR domain and five C(2)H(2)-type zinc fingers. ZNF232 is possibly a nuclear protein, as suggested by expression analysis of GFP/ZNF232 chimeric constructs. ZNF232 transcripts were detected in a wide collection of adult human tissues. The gene is possibly subjected to tissue-specific post-transcriptional regulation by means of alternative splicing.

Screening for subtelomeric chromosome abnormalities in children with idiopathic mental retardation using multiprobe telomeric FISH and the new MAPH telomeric assay.

Subtelomeric chromosomal abnormalities are emerging as an important cause of human genetic disorders. The scope of this investigation was to screen a selected group of children with idiopathic mental retardation for subtelomeric anomalies using the multiprobe telomeric FISH method and also to develop and test a new assay, the MAPH telomeric assay, in the same group of patients. The new MAPH telomeric assay uses the recently published MAPH methodology that permits the measurement of locus copy number by hybridisation with a specifically designed set of probes located at the end of human chromosomes. Seventy patients with idiopathic mental retardation have been screened using the established multiprobe telomeric FISH assay and the new MAPH telomeric assay, for all telomeres. One patient with de novo 8p subtelomeric deletion was identified. The new MAPH telomeric assay confirmed the same results in both normal and abnormal samples. This is the first description of the use of MAPH methodology to detect chromosomal imbalances near the telomeres in idiopathic mentally retarded patients. The new MAPH telomeric assay offers a new, fast, accurate and cost effective diagnostic tool to detect chromosomal imbalances near telomeres in mentally retarded patients, as well as the characterisation of known chromosomal abnormalities, spontaneous recurrent miscarriages, infertility, hematological malignancies, preimplantation genetic diagnosis, and other fields of clinical and research interests.

Origin of nondisjunction in trisomy 8 and trisomy 8 mosaicism.

Causes of chromosomal nondisjunction is one of the remaining unanswered questions in human genetics. In order to increase our understanding of the mechanisms underlying nondisjunction we have performed a molecular study on trisomy 8 and trisomy 8 mosaicism. We report the results on analyses of 26 probands (and parents) using 19 microsatellite DNA markers mapping along the length of chromosome 8. The 26 cases represented 20 live births, four spontaneous abortions, and two prenatal diagnoses (CVS). The results of the nondisjunction studies show that 20 cases (13 maternal, 7 paternal) were probably due to mitotic (postzygotic) duplication as reduction to homozygosity of all informative markers was observed and as no third allele was ever detected. Only two cases from spontaneous abortions were due to maternal meiotic nondisjunction. In four cases we were not able to detect the extra chromosome due to a low level of mosaicism. These results are in contrast to the common autosomal trisomies (including mosaics), where the majority of cases are due to errors in maternal meiosis.

SV40-mediated immortalization of human fibroblasts.

We have identified a multistep mechanism by which the DNA virus SV40 overcomes cellular senescence. Expression of SV40 T antigen is required for both transient extension of life span and unlimited life span or immortalization. These effects are mediated through inactivation of function of growth suppressors pRB and p53 via complex formation with T antigen. However, immortalization additionally requires inactivation of a novel growth suppressor gene, which has recently been identified to be on the distal portion of the long arm of chromosome 6, designated SEN6. We propose that SEN6 is responsible for cellular senescence in fibroblasts and other cells.

Evidence for high-risk haplotypes and (CGG)n expansion in fragile X syndrome in the Hellenic population of Greece and Cyprus.

The expansion of the trinucleotide repeat (CGG)n in successive generations through maternal meiosis is the cause of fragile X syndrome. Analysis of CA repeat polymorphisms flanking the FMR-1 gene provides evidence of a limited number of "founder" chromosomes and predisposing high-risk haplotypes related to the mutation. To investigate the origin of mutations in the fragile X syndrome in the Hellenic populations of Greece and Cyprus, we studied the alleles and haplotypes at DXS548 and FRAXAC2 loci of 16 independent fragile X and 70 normal control chromosomes. In addition, we studied 191 unrelated normal X chromosomes for the distribution and frequencies of CGG alleles. At DXS548, 6 alleles were found, 2 (194 and 196) of which were represented on fragile X chromosomes. At FRAXAC2, 6 alleles were found, 4 of which were present on fragile X chromosomes. Sixteen haplotypes were identified, but only 5 were present on fragile X chromosomes. The highest number of CGG repeats (> or = 33) were associated with haplotypes 194-147, 194-151, 194-153, and 204-155. The data provide evidence for founder chromosomes and high-risk haplotypes in the Hellenic population.

Fragile X premutations and (TA)n estrogen receptor polymorphism in women with ovarian dysfunction.

We studied five groups of women with ovarian dysfunction for the CGG expansion in FMR1 and a (TA)n polymorphism in the estrogen receptor gene: a) poor responders to ovarian stimulation as part of in vitro fertilization (n = 13); b) women with familial premature ovarian failure (POF) (n = 7); c) sporadic cases with POF (n = 16); d) FRAXA premutation carriers with POF (n = 7); and e) FRAXA premutation carriers without POF (n = 9). FRAXA premutation was found in one woman with familial POF. A significant association of familial POF and FRAXA premutation carriers with POF having low copy of the (TA)n polymorphism as compared to controls was observed. Our preliminary data suggest a potential role of the estrogen receptor in POF, and it may influence the variable age of menopause of the FRAXA premutation carriers.

Molecular screening of fragile X (FRAXA) and FRAXE mental retardation syndromes in the Hellenic population of Greece and Cyprus: incidence, genetic variation, and stability.

This study presents the first large, population-based molecular investigation of the fragile X (FRAXA) and FRAXE mental retardation syndromes in the Hellenic populations of Greece and Cyprus. The aims of this population screening were to determine the prevalence of FRAXA and FRAXE syndromes among idiopathic mentally retarded (IMR) individuals, to estimate the incidence in the general population, and to investigate the molecular mechanism of instability and expansion of the FMR1-repeat. Ten FRAXA patients were identified to have either the full mutation (eight) or premutation (two) from a Hellenic population of 866 unrelated IMR individuals (611 males and 255 females, age range 3-25 years). No FRAXE patients were identified among the 611 IMR males. The incidence of FRAXA in the Hellenic population of Cyprus is estimated at 1 in 4,246 males. The repeat sites from the FMR1 and FMR2 alleles were accurately determined and showed similar distribution and frequencies with other population studies. The analysis of AGG interspersion within the FMR1-repeat in normal males revealed long, pure CGG repeats within the "gray zone" as well as variation within the 3' end showing polarity of instability. This finding supports the hypothesis that the AGG interspersion and the length of the pure repeat are major factors in determining allele stability. Analysis of FRAXAC1, DXS548, and FRAXAC2 identified particular alleles and haplotypes to have a significant association with either gray zone alleles or alleles >15 pure CGG repeats. We hypothesize that this subgroup of alleles and haplotypes are associated with long pure CGGs (>15 CGG) or 35 repeats and, having shared an evolutionary past, would have the tendency to expand.

Genetic variation and intergenerational FMR1 CGG-repeat stability in 100 unrelated three-generation families from the normal population.

In order to identify genetic factors governing expansion of the CGG repeat in the FMR1 gene and to determine what predisposes or causes a normal stable allele to change to an unstable premutation allele, it is essential to study and understand the basis of normal variation. The aim of this study was to investigate genetic variation and intergenerational stability of the FMR1 CGG-repeat region in 100 unrelated three-generation families from the general population (651 meioses). The number of CGG-repeats in the FMR1 gene was determined in all 750 individuals from the 100 families (a total of 1,132 X-chromosomes), and the allele frequencies and variability were analyzed. Thirty-six different alleles (12-60 repeats) were seen with 30 (45.8%) as the most common allele; overall female heterozygosity was 73%. Most (>96%) of the normal array lengths were less than 40 repeats. Fifteen families with at least one allele equal to or greater than 40 repeats (40-60) were identified; in one of these families there was an increase of one triplet repeat during transmission from a mother to son. These findings, together with future molecular analyses, may provide data to test proposed models that attempt to explain the mutational process and the population dynamics of the triplet repeat region of the FMR1 gene, including the transition from normal to unstable alleles, or to test other putative cis-acting sequences that may be involved with instability in the FMR1 gene.

Cytogenetic and fragile X molecular testing of individuals with mental retardation of unknown etiology.

The aim of this program was to investigate the patients with Mental Retardation Of Unknown Etiology (MROUE), on the island of Cyprus. The MROUE patients were examined cytogenetically for gross chromosomal abnormalities, and by molecular methods for the Fragile X syndrome pathology. Specialized physicians examined all institutionalized or non institutionalized patients throughout Cyprus. Cytogenetic analysis was carried out on 105 individuals, six of which showed various chromosomal aberrations. PCR and Southern blot analysis were carried out on 170 patients referred for exclusion of the Fragile X syndrome. Three patients had positive findings. Although the number of cases elucidated with this general approach was not spectacular, it allowed the resolution of a few clinically equivocal cases, to the satisfaction of the clinicians and, most importantly, the relatives involved. We believe that such screening programs should continue until all cases are thoroughly examined, thus providing definite genetic counseling and psychological support, at least in those cases that are clearly resolved. Equally important is the prospect for prevention through prenatal diagnostic programs, that are already available for such conditions.

A prenatally ascertained, maternally inherited 14.8 Mb duplication of chromosomal bands Xq13.2-q21.31 associated with multiple congenital abnormalities in a male fetus.

Duplications of the X chromosome are rare cytogenetic findings, and have been associated with an abnormal phenotype in the male offspring of apparently normal or near normal female carriers. We report on the prenatal diagnosis of a duplication on the long arm of chromosome X from chromosomal band Xq13.2 to q21.31 in a male fetus with increased nuchal translucency in the first trimester and polyhydramnios at 22 weeks of gestation. Amniocentesis was undertaken and cytogenetic analysis revealed additional chromosomal material in the long arm of chromosome X at position Xq13. Analysis with high resolution array CGH revealed the additional material is in fact a duplication of the region Xq13.2-q21.13. The duplication is 14.8 Mb in size and includes fourteen genes: SLC16A2, KIAA2022, ABCB7, ZDHHC15, ATRX, MAGT1, ATP7A, PGK1, TBX22, BRWD3, POU3F4, ZNF711, POF1B and CHM. Analysis of the parents revealed the mother to be a carrier of the same duplication. After elected termination of the pregnancy at 28 weeks a detailed autopsy of the fetus allowed for genotype-phenotype correlations.

A nation-based population screening for azoospermia factor deletions in Greek-Cypriot patients with severe spermatogenic failure and normal fertile controls, using a specific study and experimental design.

Y chromosome microdeletions in the azoospermia factor (AZF) locus have been associated with spermatogenic failure. The frequency of AZF deletions is estimated to be about 10-18% in subgroups of idiopathic azoospermia and severe oligospermia, whereas the deletion frequency is estimated to be about 1.5-10.6% in the general population. Patient selection criteria as well as experimental and study design are the major factors that influence the deletion frequency. We designed a nation-based population screening with a well-defined study and experimental criteria to answer, first, what is the deletion frequency in a study population of high risk for Y deletion in the Greek-Cypriot origin and second, if there are any differences in the deletion frequency in the investigated specific subgroup of patients from different geographic/ethnic origin. Eighty Greek-Cypriot patients who met the selection criteria were included in this study as well as 50 fertile control males. The sample size is quite large when compared with the size of the population. All samples were collected from all districts of the island of Cyprus as the population is of the same religious, geographic and ethnic origin. All patients and controls had detailed clinical information and at least two semen-analysis reports based on World Health Organization standards. Samples with abnormal karyotypes, obstructive azoospermia or oligospermia with >2 x 106/mL were excluded from this study. The experimental design required a referral team and laboratory to undertake the responsibility to collect all the samples, all clinical and laboratory information, isolate DNA and carry out all tests, data analysis and interpretation. In our study, Y chromosome microdeletions have been found in patients with spermatogenic failure. Under the specific patient selection criteria and experimental design, the overall frequency is 5%, while among azoospermic patients it is 12.5%. In the subgroups of patients with idiopathic cause it is 5.9% and in idiopathic azoospermia it is 14.3%. No variation in the overall deletion frequency or the specific subgroups deletion frequency were found, as compared with frequencies found in patients from different geographic/ethnic origin.