Table 1.

Diagnostic Features of the Subtypes of CLCN7-Related Osteopetrosis

FindingSubtype of CLCN7-Related Osteopetrosis
ARO 1IAO 2ADOII 3
Radiographic changesPathognomonic 4Characteristic 5Characteristic 6
HypocalcemiaSevere to absentAbsentAbsent
AnemiaSevere to moderateMild to absentAbsent
ThrombocytopeniaSevere to absentAbsentAbsent
Visual impairmentFrequentRareVery rare
CNS involvementSevere to absentAbsentAbsent
Age of onset of symptomsBirthFirst 2 yearsFirst 10 years
1.

ARO = infantile malignant autosomal CLCN7-related autosomal recessive osteopetrosis

2.

IAO = intermediate autosomal osteopetrosis

3.

ADOII = autosomal dominant osteopetrosis type II

4.

Generalized osteosclerosis, club-shaped long bones, sclerosis of the skull base, bone-within-bone appearance

5.

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

6.

Findings include:
• 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

From: CLCN7-Related Osteopetrosis

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Adam MP, Ardinger HH, Pagon RA, et al., editors.
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