Mitochondrial DNA deletion in an 8‐year‐old boy with pearson syndrome

Abstract

Pearson syndrome (PS) (McKusick 260560) is an often fatal disease of early childhood.We describe an 8-year-old boy with PS, who showed the typical haematological symptoms in early infancy.During his later course, increased CSF protein, ptosis and retinitis pigmentosa pointed to the Kearns Sayre syndrome, another mtDNA deletion disorder.Analysis of leukocyte mtDNA revealed a 5.5-kb mtDNA deletion similar to that found in at least five other patients with PS (R6tig et al 1990). CASE REPORTG.P. was born in 1983 as the fifth child after normal pregnancy.The unrelated parents and four siblings are healthy.Birth weight was 3100g, birth length 50cm with normal neonatal adaptation.Anaemia (haemoglobin 138 g/L) was noted from birth.At age 1 month, haemoglobin (Hb) was 80 g/L.At 5 months, Hb was 66 g/L, reticulocytes 1.9%, haematocrit (Hct) 0.22, MCV 118 fl, granulocytes 0.79 x 109/L and thrombocytes 120 x 109/L.Substitution of iron was ineffective.Clinical evaluation at 6 months gave no reason for the patient's pancytopenia.Blood values were as follows: Hb 56g/L, erythrocytes 1.7 • 1012/L, Hct 0.16, MCV 94 fl, reticulocytes 2.2%, Hb Fe 17%, serum-Fe 23.7#mol/L, ferritin 123/~g/L, total leukocytes 4.6 x 109/L, granulocytes 0.37 x 109/L, thrombocytes 102 x 109/L, vitamin B12 514ng/L and folic acid > 24/~g/L.Coombs was negative, C-reactive protein < 3 mg/L.Bone marrow showed a marked vacuolization of myeloid precursor cells and erythroblasts.Transaminases were normal and serum antibodies for connatal infections (TORCH) and antinuclear antibodies were negative.Blood pH was 7.43, base excess -2 mmol/L, urine pH 6.4, with slight hyperaminoaciduria, especially increased alanine.Urinary orotic acid was normal and lactate in urine 0.13 mmol/mol creatinine.Sonography of the abdomen was normal.Nine transfusions of packed erythrocytes were necessary to stabilize haemoglobin during the next 16 months.During this period pretransfusional Hb-values were 49-79g/L, granulocytes 0.18 1.01 • 109/L and thrombocytes 59-110 x 109/L; erythrocytes were macrocytic, MCV 93-100fl.