The interest of standard and molecular cytogenetics for the diagnosis of
acute lymphoblastic leukemia in children
Abstract
Introduction: Leukemia is a malignant proliferation of lymphoid
cells blocked at an early stage of their differentiation that can invade
the bone marrow, blood, and extramedullary sites. It is due to an
underlying genetic alteration that affects many genes that encode
proteins and play a crucial role in developing lymphoid cells. The
study’s objective is to determine the role of the standard karyotype and
molecular biology for the diagnosis of ALL. Patients and
methods: We conducted a retrospective study over 13 years, between
January 2006 and December 2019, at the hemato-oncology unit at
Abderrahim Harouchi’s university children’s Hospital in Casablanca. All
the patients diagnosed with ALL de Novo during this period were included
in this study. Their data were collected from the oncology unit’s
registry, and the medical information were extracted from the files.
Statistical analysis was performed. Their results were discussed and
compared to the literature data in the diagnosis part. However, patients
who died before chemotherapy or were transferred to another facility
were excluded from the outcome analysis. Results We conducted a
retrospective study over 13 years, between January 2006 and December
2019, at the hemato-oncology unit at Abderrahim Harouchi’s university
children’s Hospital in Casablanca. An unsuccessful karyotype was
observed in 24.7%, whereas a successful karyotype was found in 75.3 %
of our patients. In the latter normal karyotype was observed in 54%,
and an abnormal one was retrieved in 46%. Numeral abnormalities were
found in 48% of the cases (especially hyperdiploidy). Structural
abnormalities were observed in 36% of the cases, and complex karyotype
in 16% of the cases. The relapse risk among patients with unsuccessful
standard karyotype after the first line of chemotherapy was higher than
in the group with a successful one. Discussion: Compared to the
literature, the findings contribute widely to the diagnosis of
successful karyotype and help to adjust the risk group, adapt the
treatment and improve the outcome in children with ALL. The unsuccessful
standard cytogenetic was observed with a significantly higher risk of
relapse and death in the statistical analysis in this group of patients.
Those results suggest the use of molecular cytogenetics such as FISH,
RT-PCR, and SKY to go beyond the limits imposed by the resolution of the
banding and reveal cryptic anomalies essentially in unsuccessful
standard cytogenetic cases to find out the underlying genetic
abnormality that might refine the diagnosis and improve the prognosis in
children with leukemia. Conclusion: Standard cytogenetics is
useful for the diagnosis and needs to be completed by molecular
cytogenetics to refine the diagnosis, especially in unsuccessful
cultures.