Table 1.

Diagnostic Features of the Subtypes of CLCN7-Related Osteopetrosis

FindingSubtype of CLCN7-Related Osteopetrosis
AROIAOADOII
Radiographic changesPathognomonic 1Characteristic 2Characteristic 3
HypocalcemiaSevere to absentAbsentAbsent
AnemiaSevere to moderateMild to absentAbsent
ThrombocytopeniaSevere to absentAbsentAbsent
Visual impairmentFrequentRareVery rare
CNS involvementSevere to absent 4AbsentAbsent
Age of onset of symptomsBirthFirst 2 yearsFirst 10 yrs
InheritanceARAR or ADAD

ADOII = autosomal dominant osteopetrosis type II; ARO = infantile malignant CLCN7-related autosomal recessive osteopetrosis; CNS = central nervous system; IAO = intermediate autosomal osteopetrosis

1.

Generalized osteosclerosis, club-shaped long bones, sclerosis of the skull base, bone-within-bone appearance; these signs are observed in all types of ARO.

2.

Findings similar to ARO, already present in early childhood, but less severe

3.

Findings:
• Osteosclerosis of the spine ("sandwich vertebrae")
• Bone-within-bone appearance, mainly in iliac wings
• Erlenmeyer-shaped femoral metaphysis
• Mild osteosclerosis of the skull base
• Transverse bands of osteosclerosis in long bones

4.

Typical signs of CNS involvement:
• Delayed psychomotor development
• Loss of abilities
• Seizures (can be also due to hypocalcemia)
• On MRI: global brain atrophy, cortical abnormalities, and in rare individuals, heterotopias

From: CLCN7-Related Osteopetrosis

Cover of GeneReviews®
GeneReviews® [Internet].
Adam MP, Feldman J, Mirzaa GM, et al., editors.
Seattle (WA): University of Washington, Seattle; 1993-2024.
Copyright © 1993-2024, University of Washington, Seattle. GeneReviews is a registered trademark of the University of Washington, Seattle. All rights reserved.

GeneReviews® chapters are owned by the University of Washington. Permission is hereby granted to reproduce, distribute, and translate copies of content materials for noncommercial research purposes only, provided that (i) credit for source (http://www.genereviews.org/) and copyright (© 1993-2024 University of Washington) are included with each copy; (ii) a link to the original material is provided whenever the material is published elsewhere on the Web; and (iii) reproducers, distributors, and/or translators comply with the GeneReviews® Copyright Notice and Usage Disclaimer. No further modifications are allowed. For clarity, excerpts of GeneReviews chapters for use in lab reports and clinic notes are a permitted use.

For more information, see the GeneReviews® Copyright Notice and Usage Disclaimer.

For questions regarding permissions or whether a specified use is allowed, contact: ude.wu@tssamda.

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.