MON-054 First Report of Monozygotic Twins with Russell Silver Syndrome in China: Recombinant Growth Hormone Therapy and 3-Year Observation

BACKGROUND: Russell Silver syndrome (RSS) is a rare genetic condition that includes an important index of suspicion when a child presents with hemihyperthrophy. There are more than 400 cases described in the literature, but twin pairs with RSS have rarely been reported. Up to now only six monozygotic twin pairs have been described [1]. However, this has not been reported in east Asian population yet. Clinical Case: A 4 years and 9 months old monozygotic twin girl with a history of growth retardation was admitted to our hospital. The first impression of the patient was: poor growth, specific facial features, asymmetry of the lower and upper limbs for length and width. Detailed physical examination revealed a small triangular face with prominent forehead, micrognathia, lips with downturned corners, and fifth finger clinodactyly on bothhands. On admission into our hospital, the examination measured a weight of 9.0 kg (-4.9SD) and a length of 88.4 cm (-5.2SD). Anthropometrically she was classified as second grade malnutrition according to World Health Organization (WHO) charts. By contrast, her twin sister was physically and anthropometrically normal. Intrauterine growth retardation, postnatal growth retardation, normal head circumference and asymmetry of the body were the major criteria that made the clinical diagnosis of Russell-Silver syndrome. Confirmation of Russell-Silver syndrome was made based on clinical findings, birth history and results of molecular genetic testing showed hypomethylation of the paternal imprinting center 1 (IC1) of chromosome 11p15.5. Recombinant human growth hormone (rhGH) was administered by subcutaneous injection once daily, in the evening, at a dose of 0.05 mg/ kg/day. The check-up visits in the outpatient were held every three months, and the following issues were evaluated: response to treatment, tolerability, and laboratory test results, with particular emphasis on carbohydrate metabolism and bone age progression. Currently, after 28 months of rhGH treatment, the girl has grown 18 cm, reaching a body height of 106.5 cm (-3.2SD, ΔHt SDSCA: 2SD). Her current weight is 14.1 kg (-2.9SD, ΔWt SDSCA: 2SD). So far, no serious adverse events have been observed. Conclusion: This is the first case of monozygotic twin with Russell Silver syndrome reported in east Asian population. The possibility of rhGH treatment can be considered in cases of documented GH deficiency in patients with Russell Silver syndrome, under close endocrinic supervision.