Bone Abstracts

Background: Calcinosis cutis, the deposition of insoluble calcium salts in the cutaneous and subcutaneous tissue, is rare during infancy. Calcifications are most frequently reported after subcutaneous fat necrosis, hypothermia in neonates or following extravasation of calcium gluconate.

Presenting problem: The patient was born at term by caesarean section because of fetal distress; the birth weight was 2426 g. At age 4 weeks, he was admitted to the hospital due to failure to gain weight. Physical examination revealed calcinosis cutis at the left wrist and forehead. His father had milder skin calcification since childhood.

Clinical management: Serum calcium, phosphate, creatinine, alkaline phosphatase, PTH, 25-hydroxyvitamin D, TSH and free thyroxine were normal. Whole exome sequencing revealed a heterozygote nonsense mutation in exon 1 of the GNAS gene (NM_001309842: c.91C>T; p.Q31* exon 1/4 stop gain) in the patient and his father. The healthy sister did not carry the mutation. This mutation was previously described as causing pseudohypoparathyroidism.

Discussion: Our case demonstrates the variable clinical phenotype of mutations of this gene and the high index of suspicion required in cases of calcinosis cutis. GNAS mutations should be considered in the differential diagnosis of calcinosis cutis, even as an isolated symptom. The genetic diagnosis provided the family useful medical information for further follow up and management and genetic counseling for future pregnancies.

Disclosure: The authors declared no competing interests.