title: Pre- and postnatal findings in trisomy 17 mosaicism.
abstract: Trisomy 17 mosaicism is one of the rarest autosomal trisomies in humans. Thus far, only 23 cases have been described, most of them detected prenatally. In only five instances has mosaicism been demonstrated in lymphocytes and/or fibroblasts postnatally, and only in these have multiple congenital anomalies (MCA), facial dysmorphisms, and mental retardation been reported. Patients with trisomy 17 mosaicism at amniocentesis and a normal karyotype in blood and fibroblasts (n = 17) were always healthy. Here, we report on pre- and postnatal clinical, cytogenetic, molecular-cytogenetic, and molecular findings in four patients with trisomy 17 mosaicism. The first case was detected in cultured but not in short-term chorionic villi and amniocytes. Due to MCA on prenatal ultrasound examination the pregnancy was terminated. The second patient is a 13-month-old healthy boy, in whom low level trisomy 17 mosaicism was detected in cultured chorionic villi only. The third patient is a 2-year-old girl with growth retardation, developmental delay, MCA, and trisomy 17 mosaicism in amniocytes, fibroblasts, and placenta, but not in blood and buccal smear. The fourth patient is a 9-year-old boy with growth and mental retardation, sensoneurinal hearing loss, and MCA. Cytogenetic analyses showed trisomy 17 mosaicism in amniocytes, skin fibroblasts, and urinary sediment cells, whereas in blood and buccal smear a 46,XY karyotype was found. Molecular investigations in all four cases indicated biparental inheritance of chromosome 17. Formation of trisomy was most likely due to a maternal meiosis I error in Patient 1 and a postzygotic non-disjunction of the paternal chromosome 17 in Patient 4. Cerebellar malformations, reported in two cases from the literature and in two reported here may be a specific feature of trisomy 17 mosaicism. Since the aberration has rarely been reported in lymphocytes, chordocentesis is not indicated in prenatal diagnosis. Prenatal genetic counseling for trisomy 17 mosaicism in chorionic villi or amniocytes should consider that the clinical significance remains uncertain.
authors.affiliation: Division of Clinical Genetics, Department of Medical Genetics, Molecular and Clinical Pharmacology, Innsbruck Medical University, Innsbruck, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Utermann
authors.forename: Mariluce
authors.initials: M
authors.lastname: Riegel
authors.forename: Dru
authors.initials: D
authors.lastname: Leistritz
authors.forename: Thomas
authors.initials: T
authors.lastname: Karall
authors.forename: Josef
authors.initials: J
authors.lastname: Wisser
authors.forename: Lorraine
authors.initials: L
authors.lastname: Meisner
authors.forename: Christine
authors.initials: C
authors.lastname: Fauth
authors.forename: Rosa
authors.initials: R
authors.lastname: Baldinger
authors.forename: Julie
authors.initials: J
authors.lastname: Johnson
authors.forename: Martin
authors.initials: M
authors.lastname: Erdel
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Taralczak
authors.forename: Richard M
authors.initials: RM
authors.lastname: Pauli
authors.forename: Alessandra
authors.initials: A
authors.lastname: Baumer
authors.forename: Albert
authors.initials: A
authors.lastname: Schinzel
authors.forename: Dieter
authors.initials: D
authors.lastname: Kotzot
mesh_terms: D000328:Adult; D000649:Amniocentesis; D000653:Amniotic Fluid / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D002871:Chromosome Banding; D002886:Chromosomes, Human, Pair 17; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007223:Infant; D007621:Karyotyping; D008297:Male; D018895:Microsatellite Repeats; D011296:Prenatal Diagnosis; D014314:Trisomy; D024182:Uniparental Disomy / Q000175:diagnosis* / Q000235:genetics*