| |
|
|
|
|
|
|
|||
|
Blood, Vol. 96 No. 3 (August 1), 2000:
pp. 859-863
From the Nuclear Medicine Department, the Department of
Bio-Statistics, and the Hematology Bone Marrow Transplantation
Department, Saint-Louis Hospital, Paris, France.
The diagnosis of Fanconi anemia (FA) is based on the
association of congenital malformations, bone marrow failure syndrome, and hypersensitivity to chromosomal breaks induced by cross-linking agents. In the absence of typical features, the diagnosis is not easy
to establish because there is no simple and cost-effective test; thus,
investigators must rely on specialized analyses of chromosomal breaks.
Because we observed elevated serum alpha-fetoprotein (sAFP) levels in
FA patients, we investigated this parameter as a possible diagnostic
tool. Serum AFP levels from 61 FA patients and 27 controls with
acquired aplastic anemia or other inherited bone marrow failure
syndromes were analyzed using a fluoroimmunoassay based on
the TRACE technology. Serum AFP levels were significantly more elevated
(P < .0001) in FA than in non-FA aplastic patients. In the
detection of FA patients among patients with bone marrow failure
syndromes, this assay had a sensitivity of 93% and a specificity of
100%. This elevation was not explained by liver abnormalities. Levels
of sAFP were unchanged during at least 4 years of follow-up, and
allogeneic bone marrow transplantation did not modify sAFP levels.
Three of 4 FA patients with mosaicism as well as 5 of 6 FA patients
with myelodysplastic syndrome were detected by this test. Heterozygous
parents of FA patients had normal sAFP levels. Measurement of sAFP
levels with this automated, cost-effective, and reproducible
fluoroimmunoassay could be proposed for the preliminary diagnosis of FA
whenever this disorder is suspected.
(Blood. 2000;96:859-863)
Fanconi anemia (FA) is an autosomal recessive disorder
characterized initially by progressive pancytopenia with diverse
congenital abnormalities, and later by increased
predisposition to malignancy.1,2 Spontaneous chromosomal
breaks enhanced by the adjunction of bifunctional alkylating agents
such as mitomycin C, a delay in the G2 phase of the cell cycle, and
predisposition to apoptosis are the main features shared by this
genetically heterogeneous disorder.2-4 At least 8 genetic
complementation groups (A-H) have been described.5 The
FANCA, FANCC, and FANCG genes have been cloned and localized to
chromosomes 16q24.3, 9q22.3, and 9p13, respectively.6-8 The normal functions of the corresponding proteins are largely unknown and
the relationship between this dysfunction and the development of
aplastic anemia or malignant transformation is thus far unclear.
Although the diagnosis is easily suspected in a child who presents a
typical constitutional phenotype with pancytopenia, in approximately
30% of the cases the diagnosis is not made or is delayed because of
the absence of associated skin, skeletal, or urogenital malformations
or suggestive familial history.9 Currently, FA diagnosis is
based on cytogenetic analysis showing increased chromosomal breaks
after incubation with DNA cross-linking agents.10,11 A flow
cytometric method based on the accumulation of FA cells in the G2/M
phase compartment of the cell cycle after incubation with alkylating
agents has also been proposed for the diagnosis of FA.3
These tests require a high degree of expertise and can result in
false-negative results in cases of myelodysplastic syndrome3 or because of mosaicism.12 Mosaicism
is characterized by an inconclusive cytogenetic analysis performed on
peripheral blood lymphocytes, a low or absent increase in the number of
chromosome breaks, a mitomycin C-resistant lymphoblastoid cell line,
and a normal cell cycle study. It has been demonstrated recently that mosaicism could be explained by the functional correction of a pathogenic mutation by an acquired sequence modification in
cis, resulting in a functionally normal protein.13
FA diagnosis in patients with mosaicism is based on the analysis of
chromosome breakage in fibroblasts or other nonhematopoietic tissues,
or on mutation analyses.
In our center, we followed a large number of patients with FA, and we
studied patients before and after allogeneic bone marrow transplantation (BMT). Serum alpha-fetoprotein (sAFP) levels were routinely measured in FA patients to detect liver
adenomas,14 which are a potential complication occurring in
patients treated with androgens. We found that the vast majority of FA
patients had stable elevated sAFP levels over time, independent of any liver complication and also independent of any specific treatment such
as androgens. We showed that this assay was simple, fast, sensitive,
and specific for FA, characteristics that could recommend it as a
reliable and simple detection test for FA.
Patients
Determination of AFP and carcinoembryonic antigen (CEA) levels
in serum
Statistical analysis Comparison of sAFP distributions in patients and controls used the nonparametric Wilcoxon test. The accuracy of sAFP measurements for the diagnosis of FA was assessed through the use of sensitivity (true positive) and specificity (true negative), which are interpretable regardless of the prevalence of the disease in the tested population and can be estimated using the case-control study design. This assumes a binary (negative/positive) diagnostic test, so we first had to dichotomize the sAFP measurements according to a threshold value, with a positive test when sAFP was above the threshold and a negative test otherwise. Receiver operating characteristic (ROC) curves, which plot the true-positive rate versus the false-positive rate associated with increasing threshold values, were computed.16 Finally, to provide information about the ability of this diagnostic test to detect or rule out the disease, likelihood ratios were computed; these allow evaluation of the predictive value of a test without requiring knowledge of disease prevalence in the population. Analysis was performed with the SAS (SAS Institute, Cary, NC) software package.
Whereas in the general healthy population, sAFP was less than 8 kIU/L, 57 of the 61 FA patients had elevated sAFP levels (median, 16 kIU/L; range, 3.5-66 kIU/L) (Figure 1).
There was a slight difference between males (median, 19 kIU/L; range,
9-66 kIU/L) and females (median, 15 kIU/L; range, 3.5-36.5 kIU/L)
(P = .06). After logarithmic transformation of the sAFP
values, no significant correlation between age of the FA patients and
sAFP levels was observed (P = .89). With a median value of
2.8 kIU/L (range, 1-7.5 kIU/L), the control group, including 27 patients with acquired aplastic anemia or other inherited non-FA bone
marrow failure syndromes, had significantly lower sAFP levels
(P < .0001) (Figure 1). A second control group, composed of
53 healthy persons (28 males and 25 females) age-matched with FA
patients (median age, 12 years), had median sAFP values of 2.1 kIU/L
(range, 0.7-5.8 kIU/L) (not shown).
In the present study, we found that measurements of sAFP in FA
patients were abnormally high (median, 16 kIU/L; range, 3.5-66 kIU/L)
as compared with values (< 8 kIU/L) in the general population and in
an age-matched control group. The difference remained highly significant when values in FA patients were compared with those in
patients with acquired aplastic anemia or other inherited non-FA bone
marrow failure syndromes (P < .0001). Elevated values of sAFP in FA patients were not related to intercurrent hepatic diseases, malignant tumors, or treatments administered to restore blood counts.17 Furthermore, elevated levels of sAFP remained
strikingly constant over a follow-up period of 4 years and were not
modified by the restoration of normal hematopoiesis following
successful allogeneic BMT. These findings led to the suspicion that
high sAFP levels are not related to a deregulated hematopoietic AFP production and that a relation exists between these high sAFP levels
and the pathophysiology of FA. Interestingly, in 3 of 4 cases, patients
with a high rate of mosaicism in peripheral blood lymphocytes had
elevated sAFP levels, whereas their cytogenetic tests and cell cycle
studies were not informative for diagnosis. Moreover, in patients with
myelodysplastic syndrome, in whom cell cycle studies may
normalize3 and lead to misdiagnosis, we found elevated sAFP
levels in all but 1 case. Of note, measurements of sAFP in FA siblings,
twins or not, were always in the same range, suggesting a genetic
origin of the AFP deregulation in FA.
We thank Dr Rose Ann Padua for helpful comments on the manuscript; Didi
Jasmin, Director of the European School of Haematology, who helped to
improve our English syntax; all of the nuclear medicine staff for
technical assistance; the nurses and physicians of the bone marrow
transplant unit; and the family support group AFMF.
Submitted July 12, 1999; accepted March 17, 2000.
Reprints: Eliane Gluckman, Hematology Bone Marrow Transplant
Unit, Hôpital Saint Louis, 1 Avenue Claude Vellefaux, 75475 Paris
Cedex 10, France; e-mail: eliane.gluckman{at}sls.ap-hop-paris.fr.
The publication costs of this
article were defrayed in part by
page charge payment. Therefore,
and solely to indicate this fact,
this article is hereby marked
"advertisement"
in accordance with 18 U.S.C.
section 1734.
1.
Fanconi G.
Familial panmyelocytopathy, Fanconi's anemia (FA). I. Clinical aspects.
Semin Hematol.
1967;4:233-245[Medline]
[Order article via Infotrieve].
2.
Young NS, Alter B.
Clinical features of Fanconi's anemia Aplastic Anemia Acquired and Inherited. Philadelphia, PA: WB Saunders; 1994:275-309.
3.
Seyschab H, Friedl R, Sun Y, et al.
Comparative evaluation of diepoxybutane sensitivity and cell cycle blockage in the diagnosis of Fanconi anemia.
Blood.
1995;85:2233-2237
4.
Ridet A, Guillouf C, Duchaud E, et al.
Deregulated apoptosis is a hallmark of the Fanconi anemia syndrome.
Cancer Res.
1997;57:17221730.
5.
Joenje H, Oostra AB, Wijker M, et al.
Evidence for at least eight Fanconi anemia genes.
Am J Hum Genet.
1997;61:940-944[Medline]
[Order article via Infotrieve].
6.
Strathdee CA, Gavish H, Shannon WR, Buchwald M.
Cloning of cDNAs for Fanconi's anemia by functional complementation.
Nature.
1992;356:763-767[Medline]
[Order article via Infotrieve].
7.
Lo ten Foe JR, Rooimans MA, Bosnoyan-Collins L, et al.
Expression cloning of a cDNA for the major Fanconi anemia gene, FAA.
Nat Genet.
1996;14:320-323[Medline]
[Order article via Infotrieve].
8.
De Winter JP, Waisfiz Q, Rooimans MA, et al.
The Fanconi anemia group G gene FANCG is identical with XRCC9.
Nat Genet.
1998;20:281-283[Medline]
[Order article via Infotrieve].
9.
Giampietro PF, Adler-Brecher B, Verlander PC, Pavlakis SG, Davis JG, Auerbach AD.
The need for more accurate and timely diagnosis in Fanconi anemia: a report from the International Fanconi Anemia Registry.
Pediatrics.
1993;91:1116-1120
10.
Berger R, Bernhelm A, Gluckman E.
In vitro effect of cyclophosphamide metabolites on chromosomes of Fanconi anemia patients.
Br J Haematol.
1980;45:565-568[Medline]
[Order article via Infotrieve].
11.
Auerbach AD, Allen RG.
Fanconi anemia diagnosis and the diepoxybutane (DEB) test.
Exp Hematol.
1993;21:731-733[Medline]
[Order article via Infotrieve].
12.
Lo Ten Foe JR, Kwee ML, Rooimans MA, et al.
Somatic mosaicism in Fanconi anemia: molecular basis and clinical significance.
Eur J Hum Genet.
1997;5:137-148[Medline]
[Order article via Infotrieve].
13.
Waisfisz Q, Morgan NV, Savino M, et al.
Spontaneous functional correction of homozygous Fanconi anaemia alleles reveals novel mechanistic basis for reverse mosaicism.
Nat Genet.
1999;22:379-383[Medline]
[Order article via Infotrieve].
14.
Lamerz R.
AFP isoforms and their clinical significance (overview).
Anticancer Res.
1997;17:2927-2930[Medline]
[Order article via Infotrieve].
15.
Mathis G.
Rare earth cryptates and homogenous fluoroimmunoassays with human sera.
Clin Chem.
1993;39:1953-1959[Abstract].
16.
Swets JA, Pickett RM.
Assessing diagnostic technologies [letter].
Science.
1980;207:1416
17.
Chayvialle JA, Courpron P, Mikaelian S, Lambert R.
Serum alpha-foetoprotein concentration in adult patients under corticoid, estroprogestative or androgen therapy.
Digestion.
1977;15:223-226[Medline]
[Order article via Infotrieve].
18.
Waldmann TA, McIntyre KR.
Serum alpha-fetoprotein levels in patients with ataxia-telangiectasia.
Lancet.
1972;282:1112-1115.
19.
Cabana MD, Crawford TO, Winkelstein JA, Christensen JR, Lederman HM.
Consequences of the delayed diagnosis of ataxia-telangiectasia.
Pediatrics.
1998;102:98-100
20.
Harper ME, Dugaiczyk A.
Linkage of the evolutionarily related serum albumin and alpha-foetoprotein genes within g11-22 of human chromosome 4.
Am J Hum Genet.
1983;35:565-572[Medline]
[Order article via Infotrieve].
21.
Whitney M, Thayer M, Reifsteck C, et al.
Microcell mediated chromosome transfer maps Fanconi anemia group D gene to chromosome 3p.
Nat Genet.
1995;11:341-343[Medline]
[Order article via Infotrieve].
22.
Chen H, Egan JO, Chiu JF.
Regulation and activities of alpha-fetoprotein.
Crit Rev Eukaryot Gene Expr.
1997;7:11-41[Medline]
[Order article via Infotrieve].
23.
Laderoute MP, Pilarski LM.
The inhibition of apoptosis by AFP and the role of AFP receptors in anti-cellular senescence.
Anticancer Res.
1994;14:2429-2438[Medline]
[Order article via Infotrieve].
24.
Semenkova LN, Dudich EI, Dudich IV.
Induction of apoptosis in human hepatoma cells by alpha-fetoprotein.
Tumour Biol.
1997;18:261-273[Medline]
[Order article via Infotrieve].
25.
Schefer H, Mattmann S, Joss RA.
Hereditary persistence of
26.
Waldmann TA, McIntire RK.
The use of radioimmunoassay for alpha-fetoprotein in the diagnosis of malignancy.
Cancer.
1974;34:1510-1515.
27.
Ferguson-Smith MA, Rawlinson HA, May HM, et al.
Avoidance of anencephalic and spina bifida births by maternal serum-alphafetoprotein screening.
Lancet.
1978;1:1330-1333[Medline]
[Order article via Infotrieve].
28.
Haddow JE, Palomaki GE, Knight GJ, et al.
Prenatal screening for Down's syndrome with use of maternal serum markers.
N Engl J Med.
1992;327:588-593[Abstract].
29.
Bloomer JR, Waldmann TA, McIntire KR, Klastkin G.
Alpha-fetoprotein in noneoplastic hepatic disorders.
JAMA.
1975;233:38-41[Abstract].
This article has been cited by other articles:
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Copyright © 2000 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||