Five years of molecular diagnosis of Fragile X syndrome (1997-2001): a collaborative study reporting 95% of the activity in France.

The Fragile X syndrome is the most common cause of inherited mental retardation. Clinical features are neither specific nor constant and molecular diagnosis is thus widely used since the characterization of the causal mutation in 1991. The aim of this project was to study the evolution of Fragile X diagnosis in France.

Pregnancy outcome following prenatal diagnosis of an isodicentric X chromosome: first case report.

An isodicentric X chromosome, idic (X)(q27) was found in a female fetus during cytogenetic studies performed on amniotic cells due to advanced maternal age. No mosaicism was observed. Although segmental inversion duplications have been described for several other chromosomes, isodicentric chromosomes are reported only for gonosomes.

Chronic lymphocytic leukemia associated with myelodysplastic syndrome and/or chronic myeloid leukemia: evidence for independent clonal chromosomal evolution.

We describe the cytogenetic findings of three cases with simultaneous or sequential development of a B-chronic lymphocytic leukemia (B-CLL) and either a myelodysplastic syndrome (MDS) in 2 cases or a chronic myeloid leukemia (CML) in one case. The coexistence of these two hematologic malignancies leads to questions about their cell of origin. Through analysis of the cytogenetic abnormalities, we studied the derivation of both malignancies.

Defining the efficiency of fluorescence in situ hybridization on uncultured amniocytes on a retrospective cohort of 27407 prenatal diagnoses.

Rapid prenatal detection of selected numerical chromosomal abnormalities by using fluorescence in situ hybridization (FISH) on uncultured amniotic fluid samples was described six years ago. It allows a very rapid identification of selected aneuploidies. We have indexed the results of our 27407 fetal karyotypes obtained by conventional cytogenetics during the last five years, noting the type of chromosomal abnormality and the reasons for prenatal diagnosis.

Fetus with Casamassima-Morton-Nance syndrome and an inherited (6;9) balanced translocation.

We report on a fetus with cranio-facial anomalies, a narrow thorax, imperforate anus with cloacal cyst, and a genitourinary malformation with absent uterus, vagina, and external genitalia. Major thoracic defects were seen on roentgenographic examination, including absent vertebrae and ribs, a supernumerary vertebra, a hemivertebra, and rib fusion. These findings are compatible with Casamassima-Morton-Nance syndrome.