The nature of cartilage stippling in chondrodysplasia punctata: histopathological study of Conradi-Hünermann syndrome

The role of the abnormalities in the distal pathway of cholesterol biosynthesis in the Conradi-Hünermann-Happle syndrome

Conradi-Hünermann-Happle syndrome (CDPX2, OMIM 302960) is an inherited X-linked dominant variant of chondrodysplasia punctata (CP) caused by mutations in one gene of the distal pathway of cholesterol biosynthesis. It exhibits intense phenotypic variation and primarily affects the skin, bones and eyes. The ichthyosis following Blaschko's lines, chondrodysplasia punctata and cataracts are the typical clinical findings. The cardinal biochemical features are an increase in 8(9)-cholestenol and 8-dehydrocholesterol (8DHC), which suggest a deficiency in 3β-hydroxysteroid-Δ8,Δ7-isomerase, also called emopamil binding protein (EBP). The EBP gene is located on the short arm of the X chromosome (Xp11.22-p11.23) and encodes a 230 amino acid protein with dual function. Explaining the clinical phenotype in CDPX2 implies an understanding of both the genetics and biochemical features of this disease. CDPX2 displays an X-linked dominant pattern of inheritance, which is responsible for the distribution of lesions in some tissues. The clinical phenotype in CDPX2 results directly from impairment in cholesterol biosynthesis, and indirectly from abnormalities in the hedgehog signaling protein pathways. This article is part of a Special Issue entitled The Important Role of Lipids in the Epidermis and their Role in the Formation and Maintenance of the Cutaneous Barrier. Guest Editors: Kenneth R. Feingold and Peter Elias.

Natural history and management of cervical spine disease in chondrodysplasia punctata and coumarin embryopathy

PURPOSE

Chondrodysplasia punctata (CDP) is a group of skeletal dysplasias manifesting with progressive cervical instability that leads to neurological deficits and eventual death. The major clinical features of CDP also present in a phenocopy known as coumarin embryopathy (CE) which results from coumarin exposure during pregnancy. The objective of this study was to assess treatment strategies employed for children affected by CDP or CE with cervical instability and to determine a strategy on how best to diagnose and treat affected neonates.

METHODS

We performed a systematic review of the English literature for cases reporting cervical spine involvement in CDP and CE and identified 44 such patients. We extracted clinical information on these disorders and identified two patients from our craniovertebral junction database of over 6,000 patients evaluated at our institution.

RESULTS

Patients most frequently present with hyperreflexia (21%) and weakness (21%), and there were various conservative treatment strategies. Twenty-one percent of patients who were treated conservatively had neurological complications in their clinical course. There were two deaths reported, one resulting from conservative treatment and one from surgical treatment. We also report long-term follow-up analysis for a patient treated at our institution for the last 30 years and agree with all other reports that suggest that monitoring patients for neurological changes is essential to prevent further neurological injury.

CONCLUSIONS

This study emphasizes the need for careful neurological and surgical evaluation of pediatric patients with cervical spine abnormalities affected by CDP or CE in order to prevent progressive instability.