Euchromatic variant 16p+. Implications in prenatal diagnosis.

BACKGROUND: Euchromatic imbalances at the cytogenetic level are usually associated with phenotypic consequences. Among the exceptions are euchromatic variants of chromosome 16 (16p+) with normal phenotype. There is a growing list of euchromatic duplications and deletions involving both G-positive and G-negative bands that seem to be phenotypically neutral, but these euchromatic variants are rare. OBJECTIVE: The aim of this report is to describe a new familial case of euchromatic variant 16p+ and to emphasise the misinterpretation of these rare euchromatic variants particularly when ascertained at prenatal diagnosis. METHODS AND RESULTS: Fluorescence in situ hybridisation with clone RP11-261A7 showed an amplified signal in the larger chromosome 16. This clone contains FLJ43855 gene, similar to sodium- and chloride-dependent creatine transporter. CONCLUSION: So, this 16p+ variant that involves amplification of pseudogenetic sequences is considered a polymorphism in normal individuals.

Comparative study of three diagnostic approaches (FISH, STRs and MLPA) in 30 patients with 22q11.2 deletion syndrome.

The 22q11.2 deletion syndrome is commonly diagnosed using fluorescence in situ hybridization (FISH) with commercial probes. The chromosomal breakpoints and deletion size are subsequently characterized by short tandem repeat (STR) segregation tests or by further FISH probes. Recently, a multiplex ligation-dependent probe amplification (MLPA) single tube assay was developed to detect deletions of the 22q11.2 region and other chromosomal regions associated with DiGeorge/velocardiofacial syndrome. We have compared the results of these three techniques in a group of 30 patients affected with 22q11.2 deletion syndrome. MLPA correctly called all patients who had been previously diagnosed by FISH. The MLPA results were concordant in all patients with the STR analysis in respect to deletion size. Furthermore, this novel technique resolved seven cases that were undetermined by STR analysis. These results confirm the efficiency of MLPA as a rapid, reliable, economical, high-throughput method for the diagnosis of 22q11.2 deletion syndrome.

Tetrasomy 8p: discordance of amniotic fluid and blood karyotypes.

We describe a girl with congenital heart defect (ventricular septal defect), facial, ear and bone anomalies, agenesis of corpus callosum and conventional cytogenetic studies showing tetrasomy 8p. The identity of the isochromosome was confirmed by fluorescent in situ hybridization (FISH) using painting, subtelomeric and alpha satellite probes for chromosome 8. The extra isochromosome was observed in 100% of cultured peripheral lymphocytes (47,XX,+i(8)(p10)), but normal chromosomes were recorded in cultured amniotic fluid. Microsatellites analysis of the patient's DNA with two markers mapping 8p showed three different peaks, and two markers mapping 8q showed two peaks. To the best of our knowledge, this patient represents the twelfth reported case of tetrasomy 8p. In addition, our report is the first case with a pure tetrasomy 8p in blood, (the other published cases are mosaic 8p), and the second case with a discordance of amniotic fluid and blood karyotypes [Robinow et al., 1989: Am J Med Genet 32:320-324].

Autosomal recessive hydrocephalus due to aqueduct stenosis: report of a further family and implications for genetic counselling.

We report on two abortuses with hydrocephalus due to congenital stenosis of the aqueduct of Silvius. The occurrence of this disorder in two siblings (a male and a female) with normal parents supports the autosomal recessive pattern of inheritance. Such a mechanism of inheritance should be taken into account when counselling families with congenital hydrocephaly due to aqueduct stenosis.

Balanced reciprocal translocation (X;20) limited to Wilms' tumor in a Wiedemann-Beckwith syndrome.

A girl aged 4 years 3 months with sporadic unilateral Wilms' tumor associated with Wiedemann-Beckwith syndrome, but without aniridia, was found to have a t(X;20) in the tumor cells. Karyotypes of peripheral blood of the patient and her parents were normal. This translocation was confined to the tumor and not been previously reported either in nephroblastoma or any other neoplastic processes. Although there is no microscopic deletion on chromosome 11 and catalase activity was not decreased, we cannot rule out the possibility of a point mutation or a submicroscopic deletion.

The 18p- syndrome. Report of five cases.

Five children, three males and two females were found to have a short arm deletion of chromosome 18. Four of them display some of the typical features of this syndrome: microcephaly, round face, hypertelorism, broad-based nose, "carp-mouth", microrethrognathia, pterygium colli, dysplastic and low set ears, clinodactily, failure to grow, muscular hypotony and mental retardation. Different hypotheses are discussed in order to explain the variable phenotypical expression of the 18 p-syndrome.

Trisomy 20p from maternal translocation and anencephaly. Case report and genetic review.

This paper concerns the case of an anencephalus male fetus with partial trisomy 20p product of a maternal translocation 46,XX, t(15;20) (p11.2;p12), ascertained by prenatal diagnosis. A cytogenetic review of previous cases is presented. Several hypotheses are discussed in order to explain the recurrent abortions of the mother and the aetiology of anencephaly in this last pregnancy.

Comparison between the meiotic activities in the male with hypogonadotropic hypogonadism and in the human fetal ovocytes.

In the testicles of males with postpuberal hypogonadotropic hypogonadism, we have detected a preleptotene phase similar to that described in the human ovary. The two characteristic stages of this phase, contraction and despiralization, were noted. In this paper the origin and the significance of preleptotene in relation to the hormonal levels are discussed.

Partial trisomy 13 due to maternal translocation t(7;13)(p22q14).

The third child of a mother with a balanced translocation (7;13) revealed a partial trisomy of chromosome 13. The cytogenetic study by conventional techniques and GTG, QFQ, THA and CBG banding techniques showed the chromosomal complement of the proposita to be 46,XX,-7,+t(7;13)(7qter leads to 7p22::13q14 leads to 13qter). A prominent intensely fluorescent satellite was observed on the 13q- of the patient's grand-mother. This satellite was not found on any chromosome in any other member of the family.

[Balanced translocation 8:10 and adrenogenital syndrome. Family study (author's transl)]. / Translocación recíproca 8:10 y síndrrome adrenogenital. Estudio familiar.

An 8:10 translocation was found in a 15-day-old female child affected with adrenogenital syndrome. Some other members of the family also showed the same chromosomal anomaly. By G-, Q- and T-banding, break and fusion points were determined at the level of 8q21 and 10q24 bands. The hormone and enzymatic tests carried out in all the members of the family revealed a 21-hydroxylase deficiency only in the proposita. Possible relationship between the manifestation of syndrome and chromosomal anomaly are discussed.

An r(22)(p11 leads to q13) in a moderately mentally retarded girl.

An r(22) was detected in a 6-year-old female patient with growth retardation, IQ of 45, and a lower quotient for verbal performance. She presents some other minor anomalies. The break and fusion points probably were at p11 and q13.

["Free" 9p trisomy in a male child with severe mental retardation (author's transl)]. / Trisomía 9p "libre" en un niño con retraso mental grave.

A new case of free 9p trisomy is described. The GTG banding technique and the Giemsa-11 method showed that the extra chromosome comprised precisely the 9pter leads to q12 segment. The carrier is an eleven-year-old male child with typical facial features: globulous nose, antimongoloid slant of palpebral fissures, downward turning of mouth angels and winged ears, severe mental retardation particularly regarding language and characteristic dermatoglyphics.

Trisomy 10p due to a de novo t(10p;13p).

A new case of trisomy 10p has been identified by means of the GTG-banding technique. The patient is a female child carrying a sporadic translocation, t(10;13)(p11;p11), and affected by microsomatia and microcephaly with facial dysmorphia, retarded growth, weight gain, and psychomotor development, and bilateral talipes.

Partial deletion of 4p16 band in a ring chromosome and Wolf Syndrome.

A new case of ring chromosome 4 in a 2-day-old female child with multiple malformations is described. By means of the GTG-banding technique, a karyotype 46,XX,r(4), (p16 leads to q35) was determined. The characteristics of the child's karyotype and the relationship with the structure of the chromosome, especially the location of the deletion that produces the syndrome, are compared with previous reports.

Study of human male meiosis. II-Q-banding in pachytene bivalents.

In continuation of the research on male human meiosis within the study of pachytene bivalents, results from the analysis of 125 cells are presented. The aim of this work is to establish Q-banding patterns and make a detailed study of chromomere counting and distribution. To obtain Q-bands Quinacrine and Pseudoisocyanine staining techniques have been used.

Study of the human male meiosis. I. G-banding in pachytene bivalents.

Results obtained from a meiotic study of 250 pachytene cells from four normal human males are presented. G-banding patterns for pachytene bivalents, obtained using trypsin treatment, are also presented; a comparative study between G-banding patterns of pachytene bivalents and G-banding patterns of mitotic chromosomes, and a study of chromomere counting and distribution, have also been made.

Cri du chat syndrome and translocation t(5p--;18p+).

Two new cases of "cri du chat" syndrome are reported in sisters aged 2 years and one month, respectively. These cases allowed us to detect a translocation t(5p--;18p+) in the mother and to study the familial segregation of this structural chromosome anomaly. At the same time, results from the dermatoglyphic analysis of the propositi as well as those of the carriers of the translocation are also reported.