Autosomal recessive osteopetrosis: variability of findings at diagnosis and during the natural course

Abstract

Objective: To determine the variability and the natural course of children suffering from autosomal recessive osteopetrosis to allow optimal counseling and decision making with respect to therapeutic intervention.

Design: Retrospective and longitudinal evaluation of clinical symptoms and natural course with emphasis on survival and sensoneurologic and hematologic findings.

Setting: Two large referral-based pediatric bone marrow transplantation units in Europe.

Patients: Thirty-three patients with autosomal recessive osteopetrosis admitted to units in Paris and Leiden between 1972 and 1988 were analyzed until last follow-up or the time at which bone marrow transplantation was performed. The great number of patients and unprecedented amount of data make this report one of the single largest clinical studies on autosomal recessive osteopetrosis.

Main results: Ocular involvement occurring at a median age of 2 months was the symptom at initial examination in half of the patients. A striking variability between patients was found. Retinal degeneration was present in three patients and associated generalized neurodegeneration was present in two. The probability of survival until the age of 6 years was about 30% for the group as a whole. The cumulative risk of developing visual or hematologic impairment in the first year of life was about 75% and leveled off afterward. Patients with early hematologic impairment, ie, before 3 months of age, especially when combined with early visual impairment, had a very poor prognosis regarding life expectancy.

Conclusions: Autosomal recessive osteopetrosis seems to be a variable disorder with a poor prognosis, especially in children with early visual and hematologic impairment. Allogenic bone marrow transplantation remains the only curative approach.