Overlap of clinical features of Smith-Magenis & Down Syndrome in newborns and infants
- Integrated Genetics, West Paterson, NJ (United States); and others
Smith-Magenis Syndrome (SMS) frequently goes unrecognized in newborns and infants as these patients do not yet demonstrate the characteristic behavioral phenotype and may only present with developmental delay and physical dysmorphism. Six of Hall`s ten cardinal features of trisomy 21 in the newborn are also frequently found in newborns with SMS, leading to an early presumptive diagnosis of DS in many of these patients. CASE No. 1: Based on clinical findings, a presumptive diagnosis of DS was given to the patient in the newborn period. Chromosome analysis of peripheral blood revealed a normal 46,XX karyotype. Given this result, the possibility of mosaic DS was raised, and a skin fibroblast study done. Again, the karyotype was reported as normal. Clinical features and cytogenetic analysis confirmed a diagnosis of SMS when the patient was 8 years old. CASE No. 2: A presumptive diagnosis of DS was made in an infant with hypotonia, facial dysmorphisms and congenital heart defects. A routine chromosome analysis was ordered, which revealed a 46,XY,del(17)(p11.2p11.2) karyotype. Indeed, approximately 38% of blood samples referred to our laboratory to rule out DS in an infant failed to demonstrate trisomy for chromosome 21. Given the high degree of clinical overlap with Down Syndrome, the diagnosis of SMS should be considered in all such patients. Additional analysis should be done to look for deletion 17p11.2 when faced with a {open_quotes}normal{close_quotes} karyotype in an infant referred to rule out DS.
- OSTI ID:
- 133635
- Report Number(s):
- CONF-941009-; ISSN 0002-9297; TRN: 95:005313-0365
- Journal Information:
- American Journal of Human Genetics, Vol. 55, Issue Suppl.3; Conference: 44. annual meeting of the American Society of Human Genetics, Montreal (Canada), 18-22 Oct 1994; Other Information: PBD: Sep 1994
- Country of Publication:
- United States
- Language:
- English
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