McCune Albright Syndrome Affecting Only One of the Monozygotic Child of Twins: A Case Report

Case Report

Austin Gynecol Case Rep. 2016; 1(1): 1007.

McCune Albright Syndrome Affecting Only One of the Monozygotic Child of Twins: A Case Report

Ganie MA¹*, Raizada N¹, Kandaswamy DS² and Hammad-u-rehman¹

¹Department of Endocrinology, Metabolism and Diabetes, All India Institute of Medical Sciences, India

²Department of Radiodiagnosis, and Endocrinology, Metabolism and Diabetes, All India Institute of Medical Sciences, India

*Corresponding author: Mohd Ashraf Ganie, Department of Endocrinology, Metabolism and Diabetes, All India Institute of Medical Sciences, New Delhi, India

Received: July 28, 2016; Accepted: December 29, 2016; Published: December 30, 2016

Abstract

McCune Albright Syndrome (MAS) is a clinically rare condition that is characterized by a triad of poly/monostotic fibrous dysplasia, café-au-lait spots, and various endocrinopathies attributed to postzygotic somatic activating mutations of the guanine nucleotide-binding protein, alpha-stimulating activity polypeptide 1 (GNAS1). This peculiar pathogenesis makes the disorder intriguing to study in monozygotic twins. MAS has been infrequently reported in monozygotic twins and is actually a rarity. Hereby, we report a pair of monozygotic twins, one of whom was diagnosed with MAS while the twin sister of the affected girl, did not show any evidence of MAS on clinical, biochemical, hormonal and radiological evaluation. Although genetic analysis has not been performed, the mutation is a dominant one and the unaffected sister is unlikely to be carrying the mutated gene. Keeping in view the rarity of the disorder, this case reports needs to be documented for further understanding of this interesting disorder.

Keywords: McCune albright syndrome; Fibrous dysplasia; Café-au-lait spots; Endocrinopathies; Twins

Introduction

McCune Albright Syndrome (MAS) is a clinically rare condition that is characterized by a triad of poly/monostotic fibrous dysplasia, café-au-lait spots, and endocrinopathies. The disorder is known to be caused by postzygotic somatic activating mutations of the guanine nucleotide-binding protein, alpha-stimulating activity polypeptide 1 (GNAS1). This mutation leads to a mosaic of normal and mutant cells, and the extent and distribution of the mutant cells dictates the clinical profile of each patient. This peculiar pathogenesis makes it intriguing to study this disease in monozygotic twins. MAS has been infrequently reported in monozygotic twins. We report a pair of monozygotic twins, one of whom was diagnosed with MAS while the other had no stigmata of this syndrome.

Case Presentation

AB, the index patient and CD the sibling, were born out of a non-consanguineous marriage as a twin delivery. Soon after birth the parents had noted that AB had brownish patches on the right side of face, neck, chest and lower back. The girl had uneventful milestones and growth till she developed vaginal bleeding at the age of three years. She was diagnosed as gonadotropin independent precocious puberty but as the vaginal bleeding stopped spontaneously further medical attention was not sought. However, she again presented with development of breast and pubic hair at the age of 6 years. She was put on injectable gonadotropin releasing hormone agonists till the age of 11 years. After stopping the treatment, she attained menarche. At the age of four years, she had a fall while playing on level ground and complained of pain in her right thigh. Radiography revealed a fracture in the right femoral shaft for which closed reduction was performed and skin traction was given. The fracture united after a period of 3 months after which she was able to walk with a limp. She attained a height of 145 cm which was below the mid parental height (166 cm). The twin sibling had an uneventful childhood. She did not have the skin lesions unlike her sister. She started her breast development at the age of 10 years and attained menarche at 13 years of age. She achieved a height of 164 cm. There was no history of fracture or limp while walking.

On examination, the index patient had large cafe au lait spots on the right side of face, neck, upper chest and back (Figure 1). Her body mass index (weight in kilograms divided by the square of height in metres) was 19.0 kg/m2. She had facial dysmorphism and lurching gait. Scoliosis of lumbar spine was noted. She had a diffuse goitre (WHO grade II). However, there were no clinical features to suggest thyrotoxicosis. There was no evidence of acral enlargement or other features of growth hormone excess. There were no striae, skin thinning or proximal myopathy.

Citation: Ganie MA, Raizada N, Kandaswamy DS, Hammad-u-rehman. McCune Albright Syndrome Affecting Only One of the Monozygotic Child of Twins: A Case Report. Austin Gynecol Case Rep. 2016; 1(1): 1007.