Prenatal diagnosis of sex chromosome aneuploidy: possible reasons for high rates of pregnancy termination.

Sex chromosome aneuploidy (SCA), when detected in amniocentesis, is usually an unexpected result of a test carried out for another purpose. For most SCAs, the prognosis is milder and less predictable than trisomy 21, and therefore parents are faced with a difficult decision regarding the option of pregnancy termination. While studies from Europe and the USA report a declining trend in termination rates for SCA, our local experience is different. During the period 1989-1998, we diagnosed 60 SCA (including mosaics) in 20 106 amniocenteses (0.29%) and 48 (80%) of these pregnancies were terminated, a significantly higher proportion than has been reported in Europe and the USA. The present study shows that the difference between our experience and others' may be related to differences in cultural norms and values. Thirty women were interviewed, of whom 23 terminated and seven continued the pregnancy. Interview analyses showed that the main reason behind the decision to terminate the pregnancy was associated with the parents' fear of non-specific abnormality of the child, and concerns about abnormal sexual development. Although genetic counseling practised in our center aims to be non-directive, 56% of the women reported that the counseling was either directive towards termination, or that they at least felt that the counselor's attitude was pro-termination. Most women (93%) reported themselves as having come to terms with their decision.

A syndrome including thumb malformations, microcephaly, short stature, and hypogonadism.

We report on eight patients from seven different families affected with a syndrome which includes thumb defects, short stature, microcephaly, and mental retardation. Most of the patients had additional malformations, in particular amenorrhoea and azoospermia in the adults. There were no haematological manifestations and the chromosomes were normal without evidence of breakage even after stimulation. In five of the cases the probands' mother received hormonal treatment before or at the beginning of her pregnancy or both. The syndrome may be inherited as an autosomal recessive trait since the patients included both males and females and their parents were related in most cases. In addition, supporting this possibility, they all originated from a small village which may be considered as an isolate. However, in all cases but one, only one person was affected in each family and there was a significant apparent excess of healthy sibs of the probands. These observations may be the result of the variability of the syndrome or a more complex type of inheritance.

Transient neonatal diabetes mellitus in a child with invdup(6)(q22q23) of paternal origin.

An association between the rare condition of transient neonatal diabetes mellitus and either uniparental disomy for chromosome 6 or dup(6)(q22q23) raised the assumption that in this location on chromosome 6 there is an imprinted gene. We diagnosed diabetes that developed in a baby girl immediately after birth and resolved after 7 weeks of insulin treatment. Due to some minor dysmorphic features, we investigated her karyotype and identified invdup(6)(q22q23). The duplication spans at least 10 cM including the DNA sites DS270,S314,S1684 and S310. This case further supports the assumption that an imprinted gene exists on chromosome 6q22-23.

t(15;21)(q15;q22.1) pat resulting in partial trisomy and partial monosomy of chromosomes 15 and 21 in two offspring.

Two sibs, carriers of unbalanced products of the translocation t(15;21)(q15;q22.1) pat, are described. The sister had Prader-Willi syndrome due to deletion 15 (pter > q15) and partial trisomy 21 (pter > q22.1); her brother had partial trisomy 15 (pter > q15) and partial monosomy 21 (pter > q22.1). The translocation breakpoint on chromosome 21 was located proximal to the SOD1 gene, within a region of 4.0 cM (2.3 Mb) between the loci D21S217 and D21S213. The correlations between the clinical presentation and the molecular findings of the two sibs are discussed in relation to other patients with partial trisomy and monosomy 21.

A complex chromosome translocation resulting in deletion 11p and associated with uveal colobomata.

A boy with a complex chromosome rearrangement of chromosomes 3, 10, and 11 resulting in a deletion of the short arm of chromosome II is presented. The occurrence of uveal coloboma as an isolated congenital malformation might suggest a chromosomal site for this ocular anomaly in proximity to the aniridia locus.

Paracentric inversion X(q21.2q24) associated with mental retardation in males and normal ovarian function in females.

We describe a familial paracentric inversion (X)(q21.2 q24) in a family with 2 male and 2 female carriers. The males were mentally retarded and the females were normal with normal ovarian function. It is suggested that a recessive mental retardation (MR) gene was disrupted by one of the inversion breakpoints, although an X-linked MR gene which by chance is linked to the inv(X) could not be ruled out. In the female carriers of the paracentric inversion a random X-inactivation was demonstrated. The normal ovarian function is an exception to the concept of "critical region" at Xq13-q26.

Simultaneous formation of inv dup(15) and dup(15q) in a girl with developmental delay: origin of the abnormal chromosomes.

Two de novo abnormal derivatives of chromosome 15, inv dup(15) and dup(15q) were found in a girl with developmental delay and mild dysmorphological signs. Fluorescence in situ hybridization, using DNA probes of the Prader-Willi/Angelman syndromes (PWS/AS) critical region and chromosome-15-specific alpha-satellite, combined with molecular analysis using dinucleotide repeat polymorphisms within the PWS/AS region and the parent-of-origin specific methylation sites at the locus D15S63, shed light on how the abnormal karyotype was formed. We suggest that a translocation between the two homologues of maternal chromosomes 15 resulted in the formation of dup(15q) and two reciprocal products: an acentric fragment of 15q that was lost and a centric fragment that underwent U-type reunion to form inv dup(15).

Isochromosome 18p in a mother and her child.

We present a familial case of isochromosome 18p [i(18p)] as a supernumerary chromosome. The mother, who is a mosaic for i(18p) with partial tetrasomy 18p syndrome, transmitted the isochromosome to her only child. The child has the full syndrome of tetrasomy 18p. This is the first case of mosaicism i(18p) in an adult patient with clinical manifestations.

The ATC (ataxia-telangiectasia complementation group C) locus localizes to 11q22-q23.

The multisystem autosomal recessive disease ataxia-telangiectasia (A-T) is determined by several genes, as evidenced by the existence of four complementation groups in this disorder. Using linkage analysis, the ATA (A-T complementation group A) gene was previously localized to chromosome 11, region q22-q23. Analysis of the segregation of RFLP markers from this region in a Jewish-Moroccan family assigned to group C indicates that the ATC (A-T complementation group C) gene localizes to chromosome 11q22-q23 as well.

Isodisomy of chromosome 7 in a patient with cystic fibrosis: could uniparental disomy be common in humans?

Maternal isodisomy for chromosome 7 was observed in a 4-year-old cystic fibrosis patient with very short stature. In an examination of 11 DNA polymorphisms spanning the entire length of chromosome 7, no paternal contribution could be shown in seven informative loci. Paternity was examined with probes for five polymorphic loci on the Y chromosome, for the pseudo beta-globin locus on chromosome 11 and by Jeffreys's hypervariable probes. The results with the latter gave a probability of 3.7 x 10(-9) for nonpaternity. Chromosomal examination revealed a centromeric heteromorphism of chromosome 7 in the mother, for which the proband was homozygous. Isodisomy of the patient was thus shown for the entire length of a maternal chromosome 7. The mechanisms leading to this isodisomy involve at least two events of abnormal cell division, events that may be meiotic, postzygotic, or both. This proband is the second reported maternal isodisomy; both were detected through homozygosity for CF. Both patients had short stature, which could have been caused by parental imprinting, since similar results have been observed in isodisomic mice. Homozygosity due to uniparental descent in man should be kept in mind as a mechanism for recessive disorders, especially for chromosome 7.

Partial deletion of the short arm of chromosome 3: further delineation of the 3p25-3pter syndrome.

A male newborn with partial deletion of the short arm of chromosome 3 is described. The patient shares most of the features with the previously reported cases. In addition, cardiac, skeletal and gastrointestinal anomalies not previously reported are described. These characteristics may help in further delineation of the syndrome.

A complex three way translocation resulting in two sibs with partial trisomy 3p23----3pter.

A male infant with multiple congenital anomalies and psychomotor retardation was found to have a translocation resulting in partial trisomy for the distal part of chromosome 3p. An older sister with similar clinical findings had an identical karyotype. Chromosome studies in the phenotypically normal parents revealed a balanced translocation in the mother involving chromosomes 3, 11, and 18. An identical translocation was found in one of the normal children.

Gas scavenging during bronchoscopy under general anesthesia.

Prevention of exposure of the endoscopist to high levels of anesthetic gases during bronchoscopy was attempted experimentally in dogs by a scavenging system. Results were compared with exposure during the conventional technique of anesthetic gas administration for clinical bronchoscopy using the rigid open ventilating bronchoscope. The scavenging system consisted of a vacuum pump applied to the open ventilating rigid bronchoscope sidearm connection during intratracheal administration of nitrous oxide, , oxygen, and halothane gas mixture. Gas samples were taken from the trachea, the proximal end of the bronchoscope, and the endoscopist's breathing zone, and analyzed by gas chromatography. Findings indicate that halothane anesthesia for bronchoscopy administered by conventional techniques is a source of air pollution in the operating room and exposes the endoscopist to subanesthetic levels of halothane that may affect psychomotor functioning. The use of the gas scavenging system lowered the concentrations of halothane and nitrous oxide at the endoscopist's breathing zone to a level at which inhalation for short periods has no clinical effects, while the concentrations of the anesthetics and oxygen in the trachea were maintained at a satisfactory level.

Hysteroscope for CO2 laser application.

Endoscopic laser surgery is becoming more common with the development of suitable instruments. A hysteroscope designed for use with a Sharplan CO2 laser is described in detail. The method of application, results of preliminary experience, and possible indications are discussed.

The SHARPLAN family of CO2 lasers for surgery.

The SHARPLAN laser systems are available with a full range of different powers: a 25 watt office system, a 40 watt and a 60 watt system for general surgery and an 80 watt for high power needs like neurosurgery, all powers measured at tissue. A full range of accessories is available for microsurgery enabling adaptation to the most popular surgical microscopes for cavitational surgery. Super-pulse models are available, minimizing the thermal damage to the tissue exposed to the laser. The interaction of the laser with living tissue and its specific use in neurosurgery are discussed.

Microprocessor-controlled scanning micromanipulator for carbon dioxide laser surgery. Technical note.

A microprocessor-controlled scanning device for use in carbon dioxide laser surgery is described. This device increases the speed of dissection, allows the surgeon to keep both hands in the operative field, and thereby decreases the fatigue associated with manual control of the micromanipulator used in a surgical laser system.