| Answer to PhotoQuiz 51 |
| Autosomal Recessive Osteopetrosis (Infantile Malignant Osteopetrosis) |
| Autosomal recessive osteopetrosis (ARO), also known as infantile malignant osteopetrosis, is a disorder characterized by abnormal expansion of the cortical and trabecular bone. The main clinical manifestations are sclerosis of the base of the skull resulting in optic nerve compression, facial palsy and hearing loss; narrowing of the bone marrow cavity and marrow insufficiency resulting in severe anemia and thrombocytopenia; increased extramedullary hematopoiesis leading to hepatosplenomegaly; hypocalcemia with tetanic seizures and secondary hyperparathyroidism; macrocephaly; fractures; and growth failure. It is genetically heterogeneous and biallelic pathogenic variants in the TCIRG1, CLCN7, OSTM1, TNFRSF11A or SNX10 gene have been reported to be associated with the severe form of ARO; variants in certain other genes including TNFSF11 and PLEKHM1 have been reported to cause milder forms. Hematopoietic stem cell transplantation is the recommended therapy, but cranial nerve dysfunction is usually irreversible. Majority of untreated children with the severe form of ARO do not survive beyond the first decade. |
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| Correct responses were given by: |
| 1. Dr Subhash Chandra Shaw, Department of Pediatrics, Armed Forces Medical College, Pune 2. Dr Nibedita Mitra, Southern Railway Headquarters Hospital, Chennai 3. Dr Jayaprakash Parameswaran, Institute of Child Health, Government Medical College, Kottayam, Kerala 4. Dr Gayatri Indla, Lotus Ultrasound and Fetal Care Centre, Kurnool, Andhra Pradesh |