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Hematological studies in children with Down syndrome
O David1, G C Fiorucci, M T Tosi
1Ospedale Infantile Regina Margherita, Torino, Italy.
Insights
Children with Down syndrome (DS) exhibit erythrocyte macrocytosis, likely due to an altered folate remethylation pathway linked to cystathionine beta-synthase (CBS) activity on chromosome 21, not reduced red cell survival.
Area of Science:
- Genetics
- Hematology
- Biochemistry
Background:
- Down syndrome (DS) is associated with erythrocyte macrocytosis in various age groups.
- The underlying mechanisms and clinical significance of macrocytosis in DS remain poorly understood.
Purpose of the Study:
- To investigate the hematological parameters in children with Down syndrome.
- To explore the potential causes of macrocytosis in DS, including red blood cell survival and folate metabolism.
Main Methods:
- Compared hematological parameters (including mean corpuscular volume and hemoglobin) of 50 children with DS (aged 2-15 years) with 68 age-matched healthy children.
- Assessed erythrocyte creatine, hexokinase activity, folate levels, vitamin B12, haptoglobin, serum iron, and ferritin in both groups.
Main Results:
- Children with DS showed significantly higher mean corpuscular volume and hemoglobin levels compared to controls.
- No significant differences were observed in erythrocyte creatine, hexokinase activity, folate, vitamin B12, haptoglobin, serum iron, or ferritin between DS patients and controls.
Conclusions:
- Macrocytosis in Down syndrome may stem from an altered folate remethylation pathway, potentially due to enhanced cystathionine beta-synthase (CBS) activity.
- This altered pathway, linked to the gene on chromosome 21, is a more probable cause than reduced red blood cell survival.
Abstract:
Previous studies have reported erythrocyte macrocytosis in adults and children with Down syndrome (DS), the significance of which remains unclear. We compared hematological parameters of 50 DS children aged 2 to 15 years, divided into three age groups, with those of 68 aged-matched healthy children. Patients with DS had a significantly increased mean corpuscular volume (MCV) and hemoglobin in all groups when compared with the controls. Erythrocyte creatine content, hexokinase (Hk) activity, erythrocyte and serum folates, vitamin B12, haptoglobin, serum iron, and ferritin were tested. All of these parameters were not significantly different from those of the control group. We conclude that macrocytosis may not be an expression of reduced red cell survival but rather of an altered folate remethylation pathway, secondary to enhanced cystathionine beta-synthase (CBS) activity, the gene for which is present on chromosome 21.