Long-term Follow Up of Carbonic Anhydrase II Deficiency Syndrome

Objective: To describe the long term clinical, biochemical and radiological features of 35 Saudi Arabian children with carbonic anhydrase II deficiency syndrome who have been followed at King Faisal Specialist Hospital and Research Center, Riyadh since 1979.

Methods: The records of these patients were retrospectively evaluated. The diagnosis was based on the clinical and the radiological evidence of the disease. Carbonic anhydrase II level was measured in 9 patients.

Results: Clinically, these patients had typical facial features, growth failure and varying degrees of psychomotor retardation. Biochemically, all children had renal tubular acidosis that was of distal type in the majority of them. Radiologically, this syndrome was characterized by metyphyseal osteopetrosis and intracranial calcification that was progressive in 2 patients. Five patients were blind secondary to optic nerve entrapment and 2 patients developed anemia and secondary erythropoesis due to bone marrow involvement. Nineteen patients had attained the final adult height; the mean adult height was 146 cm (-3 standard deviation) in 11 females and 152 cm (-4 standard deviation) in 8 males. Two patients were married and had clinically and radiologically normal children.

Conclusion: The syndrome of carbonic anhydrase II deficiency is usually benign in nature and compatible with long term survival, however it can progress and involve the cranial nerves. Close clinical and neurological assessment of these patients is mandatory to early detect and manage potential serious complications.