American Journal of Medical Genetics 83:361–364 (1999) Duplication Within Chromosome 5q Characterized by Fluorescence In Situ Hybridization David Mowat,1* Anna Jauch,2 Lisa Robson,3 and Arabella Smith3 1 Department of Clinical Genetics, Sydney Children’s Hospital, Sydney, Australia Institut für Humangenetik und Anthropologie, Heidelberg, Germany 3 Department of Cytogenetics, Western Sydney Genetics Program, Royal Alexandra Hospital for Children, Westmead, Australia 2 We present a 16-month-old boy with developmental delay, minor anomalies, small penis, and lymphedema of the upper limbs. Routine cytogenetic analysis suspected a duplication of 5q. Fluorescent in situ hybridization (FISH) with a cosmid probe (MCC at the 5q22 APC region) showed tandemly duplicated fluorescent signals on one of chromosomes 5, whereas FISH with three YAC probes (TYAC12 at 5q35, HTY3182 at 5q34, and TYAC139 at 5q31) did not give duplicated signals. These findings indicate a duplication of 5q22 band in one chromosome 5. The boy we describe here is the first case of a pure partial duplication of 5q to be proven by FISH techniques. A review of previously reported cases of putative partial 5q duplication showed no consistent phenotype. Am. J. Med. Genet. 83:361–364, 1999. © 1999 Wiley-Liss, Inc. KEY WORDS: chromosome 5; partial duplication of 5q; mental retardation; FISH; lymphedema INTRODUCTION Attempts at phenotype-karyotype correlation of partial trisomy for the long arm of chromosome 5 have been hampered because patients represent a heterogeneous group and their partial 5q duplications are of different lengths. Most cases were the result of an inherited unbalanced translocation, and therefore do not have pure partial trisomy for 5q [Ferguson-Smith et al., 1973; Jalbert et al., 1975; Osztovics and Kiss, 1975; *Correspondence to: Dr. David Mowat, Department of Medical Genetics, Sydney Children’s Hospital, Randwick, Sydney, NSW 2031, Australia. E-mail: firstname.lastname@example.org Received 19 December 1997; Accepted 17 December 1998 © 1999 Wiley-Liss, Inc. Watanabe et al., 1977; Bartsch-Sandhoff and Liersch, 1977; Zabel et al., 1978; Curry et al., 1979; Jones et al., 1979; Rodewald et al., 1980]. There were three cases of apparently pure duplications of 5q, whose breakpoints had been determined cytogenetically [Kessel and Pfeiffer, 1979; Gilgenkrantz et al., 1981; Martin et al., 1985]. We describe a boy with de novo duplication for 5q15q23.1 that was confirmed by a combination of chromosome painting with fluorescent in situ hybridization (FISH) using probes from various regions of 5q. The boy had quite a different phenotype from that of previously reported patients with a similar chromosome abnormality. CLINICAL REPORT The patient was the fourth child of healthy nonconsanguineous Caucasian parents and was born when the mother was 25 years and the father 26 years old. After an uneventful pregnancy, he was delivered at term by normal vaginal delivery with a birth weight of 3,440 g (75th centile), length of 51 cm (50th centile) and occipitofrontal circumference (OFC) of 35 cm (50th centile). He was a quiet baby and fed well. At age 4 months, he was noted to have a squint and to be delayed in his motor development. He had a normal computed tomographic scan and underwent grommet surgery for a glue ear. When re-examined at age 16 months, he was noted to have significant global delay with a developmental level between 7 to 9 months. His length was 81 cm (50th centile), weight 11 kg (25th centile), and OFC 45.7 cm (10th centile). He had blond hair, blue eyes, bitemporal narrowing, flat nasal bridge, broad nasal tip with horizontal nasal alae, long philtrum, protruding lower lip, low-set relatively large ears, with over-folding of the right helix, and a convergent squint (Fig. 1). He had lymphedema of the upper limbs distal to the midshaft of both humeri, which is slowly resolving in time. He had a small penis (<2 SD below the mean) and his testes were normal in size. He had mild truncal hypotonia over and above that expected for his developmental delay. 362 Fig. 1. Mowat et al. Patient at age 16 months, showing his broad nasal tip (A, C), relatively large ears (A–C), upper limb edema (C, D) and small penis (E). CYTOGENETIC STUDIES Routine chromosome analysis was performed on a 72-hour–cultured peripheral blood lymphocytes. Fragile X was excluded in 50 cells. All metaphase cells showed additional material on 5q. GTG-banding showed that the breakpoints were considered to be between 5q15 and 5q31 with a duplication of part of band 5q22 and all of band 5q23 (Fig. 2). Karyotypes from his parents were both normal. Chromosome slides for FISH were obtained using a cell suspension retained after routine cytogenetic harvest. The following seven probes were used for the characterization of the 5q rearrangement: three painting probes (CHR5B-Cambio for the whole chromosome 5 paint, a probe for partial chromosome 5p paint, and a microdissection probe for the whole 5q paint), one cosmid probe (the MCC probe at 5q22-APC region), and three YAC probes (TYAC12 at 5q35, HTY3182 at 5q34, and TYAC139 at 5q31). The chromosome painting with CHR5B or the 5pspecific probe showed that the additional material on 5q was derived from chromosome 5, and no chromosome 5 material was inserted anywhere else, confirming a pure duplication of 5q. The 5q microdissection probe and the 5q subtelomere probe (TYAC12) were used simultaneously. As a result, only a single twinsignal appeared on both chromosomes 5 (Fig. 3a). Likewise, hybridization with two other YAC probes also showed a single signal on both chromosomes 5 (Fig. 3b). These results indicated that the regions at which the probes are located are not duplicated. The MCC 5q Duplication Identified by FISH 363 Fig. 2. GTG-banded karyotype with a derivative chromosome 5 on the right. Arrowheads indicate proximal and distal breakpoints, and arrows indicate the MCC locus at q22. cosmid probe showed two twin-signals on one chromosome 5, indicating a duplication involving the 5q22 region (Fig. 3c). The very close proximity of the MCC signals also indicated the breakpoint to be just distal to 5q22, and an inverted duplication at 5q23.1 as the distal breakpoint. More proximal probes were not available and the proximal breakpoint was considered to be 5q15 from the routine cytogenetic findings. DISCUSSION The patient we have described is the first case of a pure partial 5q duplication to be studied and confirmed by FISH. He had a phenotype milder than that of three previously reported live-born patients with a similar duplication of 5q (Table 1). They were associated with growth failure, severe psychomotor retardation, microcephaly, and a variety of minor facial anomalies [Kessel and Pfeiffer, 1979; Gilgenkrantz et al., 1981; Martin et al., 1985], whereas our patient has normal growth, only minimal facial abnormality, mild-to-moderate psychomotor retardation, and a normal head size. In addition, our patient had a broad nasal tip, small penis, and unusual distribution of non-pitting lymphedema of the upper limbs, which is resolving. The pattern of lymphedema and clinical manifestations seen in our patient are different from those of known lymphedema syndromes, e.g., Ullrich-Turner syndrome [Jones, 1997], hereditary lymphedema types I and II, Milroy disease, lymphedema and microcephaly, and lymphedema and cerebral arteriovenous anomaly [Online Mendelian Inheritance in Man, 1996]. Thus, there is no phenotype apparently characteristic for the pure interstitial 5q duplication. A duplication detected cytogenetically should first be examined with specific library probes. If the whole chromosome is painted, as here, one can proceed to a chromosome-arm probe and/or breakpoint mapping Fig. 3. FISH on chromosomes 5 of the patient. Two-color FISH by the simultaneous use of Cy5-labeled 5q-microdissection painting probe and FITC-labeled subtelomeric probe TYAC12 (a), and that using the same painting probe and FITC-labeled TYAC139 probe (b) show single twinFITC-signal both on normal and derivative chromosomes 5, indicating that the regions where the probes are located are not duplicated. Two twinsignals (larger arrowhead) appear on the derivative chromosome 5 when using the MCC probe at 5q22, while a single twin-signal (smaller arrowhead) is seen on normal chromosome 5 (c). with unique sequence probes from the putative region. Limitations to this approach include the availability of probes. In our patient, we could not ascertain the proximal boundary of the duplication with FISH. DNA techniques and probes, which may render breakpoints accurate, are not readily available in all laboratories. Nevertheless, our case illustrates that there is a new phase in phenotype-karyotype correlation using FISH techniques to accurately confirm the cytogenetic findings. This should prevent the inclusion of cases with a different chromosomal abnormality into a clinical phe- 364 Mowat et al. TABLE I. Comparison of Cases With Putative Pure 5q Duplication* Kessel and Pfeiffer, 1979 Gilgenkrantz et al., 1981 Martin et al., 1985 This report 6 years F 33 2,800 ? + + + ? Bulbous ? ? + ? + q13-q22 4 years F 22 2,300 46 + + + − Bulbous + + + ? ? q13-q22 4 months M 20 2,290 47.5 + + + − Bulbous ? ? ? ? + q22-q33 16 months M 25 3,440 51 − + − + Broad tip + + − + − q15-q23.1 Age Sex Maternal age (years) Birth weight (g) Birth length (cm) Microcephaly Psychomotor retardation Growth delay Strabismus Nose Large ears Hypotonia Scoliosis Edema Congenital heart defect Duplication *?, Not reported; +, present; −, absent. notype and provide more accurate descriptions of clinical syndromes. ACKNOWLEDGMENTS We are grateful to Ms. Jo Hasselaar for routine cytogenetic analysis, Dr. Brian Kearney at NCH for referring the patient, Dr. Helen Donis-Keller at Washington University for providing the YAC clones, TYAC12 and TYAC139, Dr. Jeffrey Trent at NIH for the chromosome-arm specific microdissection probes, Dr. D. Koorey at Royal Prince Alfred Hospital, Sydney, for the MCC probe, and to the family for their cooperation. REFERENCES Bartsch-Sandhoff M, Liersch R. 1977. Partial duplication 5q syndrome. Phenotypic similarity in two sisters with identical karyotype (partial duplication 5q33-5qter and partial deficiency 8p23-pter). Ann Genet 20:179–184. Curry C Jr, Loughman W, Francke U, Bryan D, Golbus M, Derstine J, Epstein C. 1979. Partial trisomy for the distal long arm of chromosome 5 (region q34-qter). A new clinically recognizable syndrome. Clin Genet 15:154–461. Ferguson-Smith M, Newman B, Ellis P, Thomson D, Riley I. 1973. 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