Pseudohypoparathyroidism type 1A and morbid obesity in infancy.

Objective: To describe an infant with early excessive weight gain as the principle manifestation of pseudohypoparathyroidism (PHP) type 1a and Albright hereditary osteodystrophy (AHO).

Methods: We describe the clinical and laboratory findings in an infant with early excessive weight gain without evidence of hyperphagia and review relevant literature.

Results: The proband's birth weight was 4047 g (1.4 SD). She was breastfed from birth. Excessive weight gain was noted by 1 month of age. At 3 months of age, hard subcutaneous nodules were observed, and histologic analysis of a biopsied lesion suggested a possible diagnosis of ossified pilomatricoma. At 6 months of age, she was documented to have mild hypothyroidism. Abnormal weight gain continued despite a caloric intake of about 65 kcal/kg per day. At 11 months of age, 2 new subcutaneous hard nodules were identified, which in the context of excessive weight gain and evolving mild primary hypothyroidism, suggested a unifying diagnosis of PHP type 1a and AHO. GNAS sequence analysis was performed, which revealed a 4-base deletion (Nt565delGACT) in exon 8.

Conclusions: As more monogenic causes of severe early obesity are described, it is important to consider PHP type 1a in the differential diagnosis. Lack of short stature, skeletal abnormalities, or absence of PTH resistance should not exclude this diagnosis in a young child.