[Clinical and cytogenetic variability in 12 Mexican families with Fanconi's anemia and its relationship with the complement gruoup to which they belong].
OBJECTIVE
To describe the clinical and cytogenetic features of Mexican patients with Fanconi anemia, while assessing whether the phenotypic variation is related to the complementation group.


METHODS
The cytogenetic diagnosis was done using mitomycin C and diepoxybutane on peripheral blood lymphocytes. The severity of the anemia and each patient's clinical manifestations were classified using Alter's and Auerbach's clinical scores, respectively. Lymphoblastoid cell lines were established for eight patients and complementation group determined following cell fusion procedures in four propositi.


RESULTS
Twenty-five Fanconi anemia patients from 12 families were studied. All patients had high, spontaneous and induced chromosomal breakages, no relationship was found between the clinical severity of the disease and the anemic state. Twelve patients were considered severely ill, while the remaining 13 were considered mild cases. Three individuals were anemia-free, while in 13 the anemia was mild, moderate in 7, and severe in 1. The mortality rate was 32% (8/25). No relationship was found between the clinical picture and degree of the anemia or mortality rate. Eleven patients were assigned to complementation group A with mild clinical findings and anemia. Their cytogenetic results showed variability. One patient assigned to group C was considered as a severe case with transfusion-dependent anemia and high sensitivity to mutagens. Thirteen patients were not classified. A lymphoblastoid cell line resistant to mitomycin C was obtained suggesting somatic mosaicism.


CONCLUSIONS
The establishment of a complementation group does not necessarily explain variability. There are other important factors, such as somatic mosaicism, that modify the cellular phenotype.
Esmer Sánchez
M C
MC
Departamento de Investigación en Genética Humana, Instituto Nacional de Pediatría (INP), México, D.F.
Carnevale Cantoni
A
A
Molina Alvarez
B
B
Cruz-Alcívar
R
R
Sánchez Sandoval
S
S
Gómez Laguna
L
L
Frías Vázquez
S
S
D002869:Chromosome Aberrations; D005199:Fanconi Anemia / Q000235:genetics*; D005260:Female; D014644:Genetic Variation; D006801:Humans; D008297:Male; D008800:Mexico