American Journal of Medical Genetics 37543-545 (1990)
Brief Clinical Report
Monozygotic Twins Discordant for the Russell-Silver Syndrome Michael Samn, Kathleen Lewis, and Bruce Blumberg Department of Pediatrics, Children’s Hospital of S u n Francisco (M.S.J.L.) and Department of Genetics, Kaiser Permanente Medical Center (B.B.), S u n Francisco, California
Russell-Silver syndrome is a disorder of unknown cause. A number of familial cases have suggested autosomal dominant inheritance. We report on monozygotic twins discordant for the Russell-Silver syndrome. Our findings suggest that the cause of Russell-Silver syndrome is not explained entirely by genetic factors. The possible role of the intrauterine environment as an etiologic component of Russell-Silver syndrome is discussed. KEY WORDS: dwarfism, twins, discordance INTRODUCTION Russell-Silver syndrome (RSS)was first described by Silver et al. [19531, in 2 children with growth retardation. Russell [19541 described 5 growth-retarded infants, some with asymmetry. Subsequently it was suggested that both reports referred to the same disorder. RSS is characterized by intrauterine and postnatal growth retardation, limb asymmetry, triangular face, and downturned corners of the mouth. Growth hormone levels are normal. A detailed review and discussion of RSS can be found in a report by Marks and Bergeson [19771or a book by Nyhan and Sakati [19761.The cause of RSS is unknown. Most cases occur sporadically, but reports of familial occurrence by Escobar e t al. L19781 and Fuleihan e t al. [1971] have suggested a genetic cause. A set of monozygotic (MZ) twins discordant for RSS was noted by Nyhan and Sakati [1976]. Monozygosity was based on undescribed testing of blood groups. We are reporting a set of MZ twins discordant for RSS. Monozygosity was confirmed by placental histology, red blood cell antigens, plasma proteins, and HLA testing.
Received for publication November 27, 1989; revision received May 14, 1990. Address reprint requests to Michael Samn, M.D., Children’s Hospital of San Francisco, Department of Pediatrics, 3700 California Street, P.O. Box 3805, San Francisco, CA 94118.
0 1990 Wiley-Liss, Inc.
CLINICAL REPORT Twin girls were born to a 23-year-old, primagravid, white woman whose pregnancy was complicated by discordant size and growth ofthe twins noted by ultrasound at 29 weeks. The mother denied the use of drugs, alcohol, and tobacco. The twins were delivered by cesarean section a t 30 weeks of gestation because twin B had shown no growth for 11/z weeks. The assessment of gestational age was based on dates and ultrasound findings. The placental histology report describes the placental membranes as being diamniotic and monochorionic. The cord that was attached to twin B had a velamentous insertion. Twin A had a hematocrit of 46% and twin B of 50%, with no evidence for a twintwin transfusion. Twin A had Apgar scores of 8 and 9. Her birthweight was 1,800 g (95th centile), her length was 43 cm (75th centile), and her head circumference (OFC) was 29 cm (75th centile). The initial physical examination was consistent with a gestational age of 30 weeks by Ballard examination. She was normal on physical examination. Her hospital course was complicated by respiratory distress syndrome (RDS), pneumothorax, and hyperbilirubinemia. After discharge from the hospital, her growth and development were normal for her corrected age by Bayley Scales of Infant Development. At 18 months (chronologic age), she is alert and active (Fig. 1). She appears to be grossly symmetrical. Her weight is 11.3 kg (50th-75th centile), her length is 85 cm (95th centile), and her OFC is 46.5 cm (25th centile); centiles are based on corrected age (Fig. 2a-c). Her limbs are symmetric with arm lengths of 34 cm (acromion to fingertip) and leg lengths of 38 cm (anterior superior iliac spine to medial malleolus). There is no clinodactyly or syndactyly. She has normal muscle tone and symmetric deep tendon reflexes. Twin B had Apgar scores of 6 and 8. Her birthweight was 770 g (
Brief Clinical Report
Monozygotic Twins Discordant for the Russell-Silver Syndrome Michael Samn, Kathleen Lewis, and Bruce Blumberg Department of Pediatrics, Children’s Hospital of S u n Francisco (M.S.J.L.) and Department of Genetics, Kaiser Permanente Medical Center (B.B.), S u n Francisco, California
Russell-Silver syndrome is a disorder of unknown cause. A number of familial cases have suggested autosomal dominant inheritance. We report on monozygotic twins discordant for the Russell-Silver syndrome. Our findings suggest that the cause of Russell-Silver syndrome is not explained entirely by genetic factors. The possible role of the intrauterine environment as an etiologic component of Russell-Silver syndrome is discussed. KEY WORDS: dwarfism, twins, discordance INTRODUCTION Russell-Silver syndrome (RSS)was first described by Silver et al. [19531, in 2 children with growth retardation. Russell [19541 described 5 growth-retarded infants, some with asymmetry. Subsequently it was suggested that both reports referred to the same disorder. RSS is characterized by intrauterine and postnatal growth retardation, limb asymmetry, triangular face, and downturned corners of the mouth. Growth hormone levels are normal. A detailed review and discussion of RSS can be found in a report by Marks and Bergeson [19771or a book by Nyhan and Sakati [19761.The cause of RSS is unknown. Most cases occur sporadically, but reports of familial occurrence by Escobar e t al. L19781 and Fuleihan e t al. [1971] have suggested a genetic cause. A set of monozygotic (MZ) twins discordant for RSS was noted by Nyhan and Sakati [1976]. Monozygosity was based on undescribed testing of blood groups. We are reporting a set of MZ twins discordant for RSS. Monozygosity was confirmed by placental histology, red blood cell antigens, plasma proteins, and HLA testing.
Received for publication November 27, 1989; revision received May 14, 1990. Address reprint requests to Michael Samn, M.D., Children’s Hospital of San Francisco, Department of Pediatrics, 3700 California Street, P.O. Box 3805, San Francisco, CA 94118.
0 1990 Wiley-Liss, Inc.
CLINICAL REPORT Twin girls were born to a 23-year-old, primagravid, white woman whose pregnancy was complicated by discordant size and growth ofthe twins noted by ultrasound at 29 weeks. The mother denied the use of drugs, alcohol, and tobacco. The twins were delivered by cesarean section a t 30 weeks of gestation because twin B had shown no growth for 11/z weeks. The assessment of gestational age was based on dates and ultrasound findings. The placental histology report describes the placental membranes as being diamniotic and monochorionic. The cord that was attached to twin B had a velamentous insertion. Twin A had a hematocrit of 46% and twin B of 50%, with no evidence for a twintwin transfusion. Twin A had Apgar scores of 8 and 9. Her birthweight was 1,800 g (95th centile), her length was 43 cm (75th centile), and her head circumference (OFC) was 29 cm (75th centile). The initial physical examination was consistent with a gestational age of 30 weeks by Ballard examination. She was normal on physical examination. Her hospital course was complicated by respiratory distress syndrome (RDS), pneumothorax, and hyperbilirubinemia. After discharge from the hospital, her growth and development were normal for her corrected age by Bayley Scales of Infant Development. At 18 months (chronologic age), she is alert and active (Fig. 1). She appears to be grossly symmetrical. Her weight is 11.3 kg (50th-75th centile), her length is 85 cm (95th centile), and her OFC is 46.5 cm (25th centile); centiles are based on corrected age (Fig. 2a-c). Her limbs are symmetric with arm lengths of 34 cm (acromion to fingertip) and leg lengths of 38 cm (anterior superior iliac spine to medial malleolus). There is no clinodactyly or syndactyly. She has normal muscle tone and symmetric deep tendon reflexes. Twin B had Apgar scores of 6 and 8. Her birthweight was 770 g (
