No abstract

In 1952, Goldenhar described a pair of monozygotic twins who were discordant for epibulbar dermoids, auricular appendages, malformations of the auricle, and hemifacial microsomia. Eighteen twin pairs have subsequently been described in which at least one member exhibited these manifestations. We report on an additional pair of discordant dichorionic monozygotic male twins. All of the 5 monozygotic twin pairs for which placental information is available have been discordant and 2 of these had dichorionic membranes. The failure of discordant monozygotic twins to be limited to monochorionic pairs argues against the hypothesis that developmental abnormalities arising from the placental vascular anastomoses that are commonly found in monozygotic twins is the probable explanation for the discordant expression of these traits in twins.

No abstract

Mosaic trisomy 5 is a very rare condition in liveborns, with few cases reported in the last four decades. There are some reports of prenatally diagnosed mosaic trisomy 5 resulting in phenotypically normal offspring, suggesting a low level of mosaicism, but there are also reports associated with multiple congenital anomalies, cardiovascular malformations, and intrauterine growth restriction. We report an infant male diagnosed with mosaic trisomy 5 (5/15 cells) via amniocentesis. The patient was subsequently found to have uniparental disomy 5 (UPD5) by postnatal chromosome microarray, but high-resolution chromosome analysis on peripheral blood did not identify trisomy 5. Dysmorphic features included a tall forehead with low anterior hairline, hypertelorism, low-set ears, and a prominent nose and midface. Other anomalies included bilateral bifid thumbs, hypospadias, a perineal fistula, unilateral multicystic kidney, and decreased subcutaneous fat with loose skin. He had complex congenital heart disease consisting of ventricular and atrial septal defects and polyvalvular defects. The patient died at age one after a prolonged admission. We add this case to the literature with the added benefit of data from a postnatal microarray, which was not available in other cases, to broaden the phenotype of mosaic trisomy 5 and UPD5.With the current available technology, we stress the importance of postnatal genetic testing to confirm prenatal cytogenetic findings in order to further define such phenotypes. This will provide the most accurate information and counseling to affected families.