A novel mutation in the thyrotropin (thyroid-stimulating hormone) receptor gene in a case of congenital hypothyroidism.

Congenital hypothyroidism (CH) occurs approximately with a frequency of 1 in 3000-4000 births, being a disease caused by defects in thyroid hormone synthesis associated either with goiter presence or with agenesis or ectopy of the thyroid gland. A study of some familial cases has allowed identification of mutations in several known genes, including that encode the thyroid-stimulating hormone receptor (TSHR). We report a familial case of CH that transmitted as a recessive trait and caused by a novel homozygous nonsense mutation in TSHR with an initial diagnosis of thyroid agenesis hypoplasia. Genomic DNA was obtained from two siblings and their parents; TSHR was amplified using pairs of overlapping exonic primers; and polymerase chain reaction products were automatically sequenced. The propositus was homozygous (genotype: M/M) for a novel C to G transversion (1431C>G), producing a nonsense mutation, Y444X, in the first intracellular loop of TSHR, rendering a truncated receptor. Thus, the observed unresponsiveness to TSHR may be due to absent insertion of the truncated receptor into the cell membrane (if it gets translated at all) or the truncation may lead to nonsense-mediated mRNA degradation (its unresponsive to TSH). Both parents were heterozygous (wWt/M) and unrelated, as known from family history. The other daughter was homozygous for both wild-type alleles (wWt/wWt).

Y-chromosomal diversity in Europe is clinal and influenced primarily by geography, rather than by language.

Clinal patterns of autosomal genetic diversity within Europe have been interpreted in previous studies in terms of a Neolithic demic diffusion model for the spread of agriculture; in contrast, studies using mtDNA have traced many founding lineages to the Paleolithic and have not shown strongly clinal variation. We have used 11 human Y-chromosomal biallelic polymorphisms, defining 10 haplogroups, to analyze a sample of 3,616 Y chromosomes belonging to 47 European and circum-European populations. Patterns of geographic differentiation are highly nonrandom, and, when they are assessed using spatial autocorrelation analysis, they show significant clines for five of six haplogroups analyzed. Clines for two haplogroups, representing 45% of the chromosomes, are continentwide and consistent with the demic diffusion hypothesis. Clines for three other haplogroups each have different foci and are more regionally restricted and are likely to reflect distinct population movements, including one from north of the Black Sea. Principal-components analysis suggests that populations are related primarily on the basis of geography, rather than on the basis of linguistic affinity. This is confirmed in Mantel tests, which show a strong and highly significant partial correlation between genetics and geography but a low, nonsignificant partial correlation between genetics and language. Genetic-barrier analysis also indicates the primacy of geography in the shaping of patterns of variation. These patterns retain a strong signal of expansion from the Near East but also suggest that the demographic history of Europe has been complex and influenced by other major population movements, as well as by linguistic and geographic heterogeneities and the effects of drift.

Molecular analysis of Y chromosome long arm structural instability in patients with gonadal dysfunction.

We have performed cytogenetic and molecular analyses of 45,X mosaics involving structurally abnormal Y chromosomes. Karyotypes were performed by standard cytogenetic methods and, in some cases, by fluorescence in situ hybridization, to distinguish monocentric and dicentric chromosomes. In addition, the deletions of Yq have been mapped using Southern blotting and polymerase chain reaction analysis. This paper provides additional information on the analysis of Y chromosome aberrations, and suggests that the stability of the Y chromosome in these instances is related to the site of the break point on Yq.

Rapid fragile X carrier screening and prenatal diagnosis using a nonradioactive PCR test.

OBJECTIVE: To develop a rapid, nonradioactive test using the polymerase chain reaction (PCR) capable of detecting full fragile X mutations, premutations, and resolving normal alleles and to apply this to prenatal diagnosis and carrier screening of pregnant women at risk for fragile X carrier status. DESIGN: Prenatal and blood sample PCR analysis with confirmation by direct Southern blotting and cytogenetic techniques. SETTING: Samples sent to a DNA diagnostic research laboratory at a tertiary referral center. PARTICIPANTS: Pregnant women with a family history of undiagnosed mental retardation or known fragile X syndrome and controls. RESULTS: A rapid, nonradioactive PCR screening protocol for the fragile X mental retardation-1 gene for both normal and mutant alleles was developed. Analysis of 570 control X chromosomes showed a modal number of 30 CGG repeats (range, 12 to 52 repeats) and a calculated heterozygosity of approximately 80%. No excess of homozygosity was found, indicating the test was accurate for normal allele resolution. In addition, 150 unrelated pregnant women were screened. Within known fragile X families, five of 20 pregnant women were diagnosed as carriers. Two new fragile X families were diagnosed among relatives of 130 females with family histories of undiagnosed mental retardation, although no carriers were identified. Prenatal PCR testing of 28 carriers accurately detected nine fetuses with full mutations. CONCLUSIONS: This rapid, nonradioactive PCR protocol allows accurate resolution of normal alleles as well as simultaneous detection of carrier alleles and full mutations. With this approach, efficient screening of pregnant women at risk for fragile X carrier status, subsequent genetic counseling of identified carriers, and reliable prenatal diagnosis can be offered.

Cytogenetic and molecular identification of a de novo direct duplication of the long arm of chromosome 4(q21.3-->q31.3).

We report on a 3-year-old boy with moderate developmental retardation, microcephaly, and malformations of ears, lids, mouth, and thumbs. Cytogenetic analysis demonstrated a direct duplication of chromosome subregion 4(q21.3-->q31.3). Confirmation of this specific rearrangement was performed by fluorescent in situ hybridization (FISH) with a chromosome painting probe and by means of quantitative Southern hybridization with DNA probes localized within the chromosome 4 region presumed to be duplicated.

Reassessment of a chromosome 12q+ marker by fluorescent in situ hybridization (FISH).

We present a case previously described by Jenkins et al. (1983) as atypical Down syndrome (DS). The initial diagnosis was first made on the basis of phenotypic and cytogenetic data. This analysis was supported by studies of superoxide dismutase (SOD1) activity that maps to band 21q22.1. Results from phenotypic, chromosome banding and SOD1 studies suggested a karyotype of 46,XX,-12,+t(12pter to 12qter::21q21 to 21q22.?2). Using fluorescent in situ hybridization (FISH) for chromosome painting with DNA libraries derived from sorted human chromosomes to stain selectively the chromosomes No. 21 and No. 12, we demonstrate that the marker chromosome 12q+ has no chromosome 21 content but it is derived from chromosome 12.

[Cytological examination of the amniotic fluid in normal pregnancy and in cases of fetal central nervous system abnormalities]. / Badania cytologiczne plynu owodniowego w ciazy fizjologicznej oraz w przypadkach wad centralnego ukladu nerwowego u plodu.

Cytological and biochemical investigations were carried out on 60 samples of amniotic fluid obtained from 30 pregnant women with risk for development of fetal central nervous abnormality (FCNA) and 30 pregnant women in whom prenatal diagnosis was indicated for other reasons (control group). Cytological evaluation was done in an interference-polarization Nomarski microscope evaluating the cells in direct preparation and after staining with neutral red. Parallelly with cytological evaluation alpha-1-fetoprotein (AFP) and acetylcholinesterase (AChE) were determined in amniotic fluid. In three cases with open neural tube anomaly characteristic cells with strongly puckered and vacuolized cytoplasmic membranes were found. In these cases the levels of AFP and AChE exceeded the normal range. In two cases of closed abnormalities of the central nervous system diagnosed by ultrasonography no abnormalities were note by cytological and biochemical methods. The study confirmed the usefulness of the cytological examination of amniotic fluid, as a method supplementing biochemical and ultrasonographic investigations as part of prenatal diagnosis.

Regular trisomy 21 not accompanied by increased copper-zinc superoxide dismutase (SOD1) activity.

The Cu-Zn superoxide dismutase (SOD1) activity was estimated in red blood cells in children with regular trisomy 21. We report patients displaying typical Down syndrome clinical features and with SOD1 activity in the normal range.