Early prenatal diagnosis of Fanconi anaemia in a twin pregnancy, using DNA analysis

Fanconi's anemia in monozygotic twins

Fanconi's anemia is one of the inherited causes of bone marrow failure. It is inherited in autosomal recessive fashion. It presents as aplastic anemia usually at the age of 7-8 yr. Leukemias and solid tumours are complications in those who manage to survive beyond two decades. Though it has been seen in siblings, reports in monozygotic twins have been very few.

Prenatal exclusion/confirmation of Fanconi anemia via flow cytometry: a pilot study

OBJECTIVE

To explore the potential of flow cytometry in the prenatal exclusion or confirmation of Fanconi anemia (FA).

METHODS

Indications for prenatal diagnosis were (1) FA-negative family history, but suspicious ultrasound findings such as radial ray aplasia, (2) FA-positive family history, but without knowledge of the affected gene and/or mutation. Amniotic fluid (AF) cell cultures and umbilical cord (UC) blood cultures were assayed for typical cell cycle changes (G2-phase accumulations) without and with mitomycin C (MMC) treatments using single- and dual-parameter (BrdU-Hoechst) flow cytometry.

RESULTS

Single-parameter flow cytometry correctly identified 2 positive and 9 negative cases on the basis of MMC sensitivity of cultivated AF cells. Likewise, 8 negative and 2 positive cases were correctly predicted using bivariate flow cytometry of 72-hour UC blood cultures. In contrast, bivariate flow cytometry applied to AF cells grown in the presence of bromodeoxyuridine (BrdU) yielded false-positive and false-negative results.

CONCLUSIONS

Single-parameter flow cytometry of AF cell cultures and bivariate flow cytometry of UC cell cultures have the potential to correctly predict the affected status in cases at risk for FA, whereas bivariate flow cytometry proved unreliable when applied to BrdU-substituted AF cell cultures. Cases with a low a priori risk (e.g. sonographic finding of radial ray abnormalities and negative family history) would benefit most from flow cytometry as a rapid and economical prenatal screening procedure.

Variable pathogenicity of exon 43del (FAA) in four Fanconi anaemia patients within a consanguineous family

Four Fanconi anaemia group A (FAA) patients within two related consanguineous families are presented: the propositus (male, 13 years, transplanted at age 10), and his three cousins (one male, 8 years, and two female newborns). Assignment of the patients to FAA was based on the functional complementation analysis by somatic cell hybridization and confirmed by mutation screening showing a homozygous deletion of exon 43 (4267-4404del) in the FAA gene to be present in all four patients. The newborn patients had been diagnosed prenatally by DNA analysis. In spite of identical molecular pathology and close familial relationship the clinical phenotypes of the four patients were not concordant. Discordant symptoms included birthweight, pigmentation abnormalities, skeletal, renal and genital abnormalities, whereas microcephaly and possibly the haematological course were concordant. Differences in environmental conditions and/or genetic make-up along with chance effects during development may explain discordant phenotypes despite identical molecular pathology in these patients. However, our results do not rule out the possibility that the exon 43del mutation may have prognostic value for the haematological course of the disease.

Baller-Gerold syndrome associated with congenital portal venous malformation

We report a 4 year old boy in whom the clinical features of craniosynostosis and bilateral absent radii led to a diagnosis of Baller-Gerold syndrome. Additional congenital abnormalities included midface hypoplasia, atrial and ventricular septal defects, right hydronephrosis, partial sacral agenesis, and anterior ectopic anus. Evidence of portal venous hypertension was present from 8 months and a congenital portal venous malformation was discovered at 2 years. This is the first reported case of Baller-Gerold syndrome associated with a congenital portal venous malformation. We discuss the diagnostic confusion between this syndrome and other overlapping malformation syndromes and propose optimal evaluation strategies aimed at clarifying the nosology of these syndromes.