Objective of study: Aplasia of the erythropoiesis without any other affection of bone marrow function, is seen as two major conditions in children: a congenital chronic form (Diamond Blackfan anaemia, DBA) and a transient form (transient erythroblastopenia of childhood, TEC). Aplasia may also be caused by parvovirus B 19 in children as well as in adults, but anaemia is usually diagnosed in case of coexistant haemolytic disease. While heredity in DBA is well established from studies of large families and its corresponding genedefect recently has been discovered, TEC has seldom been described in more than one member of a family. Does the occurence of TEC in siblings indicates a hereditary connection?

Methods used: During the years 1987-1989 TEC was found in 51 previous healthy Swedish children less than 3 years old. Among these children there were four pairs of siblings, out of whom two girls were identical twins. The hospital records of the siblings were retrospectively analyzed and the laboratory findings were based on standard haematological methods. Moreover, histocompatibility investigations were performed in 3 of the families.

Results: The probability to find 4 pairs of siblings with TEC in 50 families was estimated to considerably less than 10-6. There were no environmental connection found and no HLA association was proven. The twins had the disease simultaneously. Their anaemia was transient and did not reccur but showed some features usually seen in DBA. The other pairs of siblings were diagnosed with “classical” TEC and several years passed between their diagnoses. Transient anaemia was reported in two of the fathers at the time of their childhood.

Conclusions: The findings indicate that TEC may be explained by hereditary factors, possibly following an autosomal dominant pattern. Since the gene associated to DBA is discovered, it would be of interest to investigate if TEC might be allelic to DBA.