POSTER NO: 263

Birth Incidence and Pattern of Osteochondrodysplasia in an Inbred High Risk Population

¹L. Al-Gazali, ²M. Bakir, ²Z. Hamid, ³E. Varady, ⁴M. Varghes, ³D. Haas, ¹A. Bener, ¹R. Padmanabhan, ¹Y. Abdulrazzaq, ¹A. Dawodu
¹UAE University Faculty of Medicine and Health Sciences, Departments of Paediatrics, Community Medicine and Anatomy, P.O. Box 1766, Al Ain, UAE, ²Ministry of Health, Al Ain Hospital Dept. of Paediatrics, Al Ain, UAE, ³Ministry of Health, Tawam Hospital, Departments of Paediatrics and Radiology, Al Ain, UAE, ⁴Oasis Hospital, Paediatrics Dept., Al Ain, UAE

Aim: Define the pattern and incidence of the different types of osteochondrodysplasias in the United Arab Emirates (UAE) population which has unique characteristics, is highly inbred and where termination of pregnancy is not accepted.

Material and Methods: All infants with a birth weight of 500gm and above in the 3 hospitals in Al Ain Medical District of UAE were prospectively studied over a period of 5 years. Almost 99% of births occur in these 3 hospitals. For each livebirth or stillbirth with suspected skeletal dysplasia, a detailed clinical and radiological examination was performed. Information regarding parental age, ethnic origin, family history and level of consanguinity was obtained and a pedigree was constructed in each case. A detailed pregnancy history with emphasis on the environmental factors and drug exposure was also obtained.

Results: Of the 38,048 births that occurred during the study period, 36 (9.46/10,000 births) had skeletal dysplasia. Eighteen cases were autosomal recessive type (4.7/10,000 births), 10 had a new dominant mutation type (2.62/10,000), 5 were autosomal dominant type (1.3/10,000 births) and 1 was x-linked recessive type (0.26/10,000 births). In 2 cases the inheritance was unknown but the parents were consanguineous. The most common recessive type of skeletal dysplasia in our series was fibrochondrogenesis (1.05/10,000 births), followed by chondrodysplasia punctata (0.78/10,000 births). Schwartz-Jampel Syndrome (SJS), Ellis-van-Creveld (EVC) and short rib polydactyl III (SRP III) each had an incidence of 0.52/10,000 births.

The incidence rate of skeletal dysplasia doubled in the last 2 years of the 5 year period of observation (6.74/10,000 in 1996 vs 12.86/10,000 in 1999 and 13.45/10,000 in 2000). This increase involved cases caused by new dominant mutations and occurred mainly in the first half of 1999 suggesting that a newly introduced environmental factor was likely to have played a causal role.

Conclusion: This prospective study has identified a high incidence of skeletal dysplasia among a population with high risk factors. It thus represents an accurate incidence figure of this group of birth defects in this country. These data will provide a useful baseline with which to assess the impact of any future changes in risk factors and other preventive health care measures.