Bone Abstracts

Background: The co-occurrence of achondroplasia with Trisomy 21 is extremely rare, with only a handful of published case reports in the literature.

Presenting Problem: A baby girl had an antenatal diagnosis of incomplete atrioventricular septal defect (AVSD), and a subsequent postnatal diagnosis of Trisomy 21. At birth she had respiratory distress and required CPAP until 5 days of life. AVSD was confirmed on postnatal ECHO. Phenotypic traits consistent with Trisomy 21 were noted, and confirmed on karyotype. She was discharged home on day eight. In neonatal follow up clinic at 7 weeks old she was noted to have a relatively large head (OFC on the 90th centile compared to weight and length which were on the 9th and 20th centile respectively) right sided plagiocephaly, short limbs with rhizomelic shortening, trident hands and a lumbar gibbus.

Clinical management: Skeletal X-rays showed shortening of the long bones, especially femur and humerus, squared iliac bones and narrow sacrosciatic notches, in keeping with a diagnosis of achondroplasia. Further genetic tests confirmed the diagnosis of achondroplasia. Health surveillance for each condition is different. Specific airway issues arise with both conditions which was especially important for this baby who required intubation and ventilation for cardiac surgery. Specific handling advice is required for infants with achondroplasia due to a large head, and this was vital due to her hypotonia. The multi-disciplinary team approach with specialist OT input has been helpful in the ongoing management of this patient.

Discussion: The presence of Trisomy 21 and achondroplasia in the same patient is rare. The first case was published in 1970 and to date there are only seven published case reports. Both conditions have distinguishable phenotypic features which are relatively commonly seen in paediatrics. Disease specific health surveillance is required, and has increased significance when these two conditions occur together. Disease specific multidisciplinary input was key in optimizing her clinical care.

Disclosure: The authors declared no competing interests.