Clin Genet 1999: 56: 328–332Printed in Ireland. All rights reser6ed

Letter to the Editor

A half cryptic derivative der(18)t(5;18)patidentified by M-FISH and subtelomereprobes: clinical findings and review ofsubtelomeric rearrangements

To the Editor:We present a 20-year-old proband and her fatherwith a subtelomeric rearrangement 46,XY/XX,add(18)(p11.32). ish der(18)t(5;18)(p15.3;p11.32)-(wcp18− , wcp5+ , tel5p+ , tel18p− , D5S23− ).The proband has a mild phenotype and borderlineintelligence. The father had some learning disabili-ties at school. Both father and daughter havemonosomy 18p11.32pter and trisomy 5p15.3pter(Fig. 1).

Deletion of 18p is probably the most frequentautosomal deletion (\100 cases). Familial trans-mission has been recorded in less than 10% of cases(1). A deletion del(18)(p11.2) or a mosaic del(18p)is reported in mothers with a normal phenotype ormild mental retardation and in severely affected ormentally retarded or short-stature offspring (2–4).In the present family, del(18)(p11.32)pat had mildphenotype effects, and therefore this deletion maybe associated with a mild phenotype. The putativegene for holoprosencephaly (HPE4 or TGIF) islocalized to 18p11.3 (5, 6). It is likely that HPE4 islocated proximal to the breakpoint in our familyor holoprosencephaly is not seen because of lowpenetrance. The proband in this study had shortstature, round face, depressed midface, down-turned mouth, and clinodactyly; features associ-ated with 18p deletion. These clinical findings seemto overlap with the mothers’ features and, hence,may be inherited traits and not associated with thedeletion. Two cases with 18p11.2pter deletion (7, 8)had keratosis pilaris, which was not observed inour cases. Hence, the gene/s disposing to keratosispilaris are probably within 18p11.2 proximal to thebreakpoint in our cases. The present cases mayprovide some insights into phenotypic variabilityassociated with 18p deletions.

The 5p15.3pter on 18p is distal to D5S23 probefrom the cri-du-chat syndrome region (Fig. 1f).

The frequent clinical manifestations in duplication5p are: minor facial anomalies, cardiac defects,renal and intestinal malformations, limb abnor-malities, and moderate to severe mental retarda-tion (9). A de no6o tandem duplication of 5p14pter(10) exhibited minimal phenotypic effects; there-fore, the critical region for causing significant clini-cal anomalies was proposed to be proximal to 5p14(10). A patient with an inverted duplication5p14p15.3 also had a mild phenotype and supportsthis hypothesis (9). The cases in this study hadtrisomy 5p15.3pter and learning difficulties. Com-paring these four cases ((9, 10) and present cases),the phenotype associated with 5p duplication doesnot appear in the terminal 5p15.3pter duplications.The two cases with 5p14p15.3 duplication (9, 10)share language and motor delay and were mildlyaffected. There appears to be a gradation of clini-cal effect in 5p duplications; 5p15.3pter probablyhave learning difficulties, 5p14p15.3 duplicationshave developmental delay, particularly languageand motor delay and possibly mild phenotypicabnormalities, and 5p duplications have severemental retardation and anomalies of multiple or-gans. The cases in this study have provided clinicalinformation to divide duplications within 5p14pterinto proximal and distal duplications. Accumula-tion of more clinical cases with these duplicationscan only strengthen the proposed assignment ofclinical features to the terminal region of 5p.

Table 1 provides a summary of subtelomericcryptic rearrangements in the literature. A system-atic search for subtelomeric translocations andtruncations in the mentally retarded was under-taken, and 6–23% positive cases were found (11–13). Since subtelomeric rearrangements can also bepresent in the normal population (14) or with mildlearning disabilities (present family), their preva-lence may be higher than previously estimated.

328

Letter to the Editor

Fig. 1. a) Partial karyotype of 46,XY/XX,add(18)(p11.32). ish der(18)t(5;18)(p15.3;p11.3)(wcp18− , wcp5+ , tel5+ , tel18− ,D5S23− ) in the father and proband shows the normal 5 pair, a normal 18 on the left and a derivative 18 on the right. The arrowon the derivative 18 shows 5p15.3pter. On the ideogram, the arrow on the left chromosome indicates the breakpoint involved andthe bracket on the derivative 18 shows the 5p15.3pter. FISH studies on the proband show that the additional material on 18p isfrom chromosome 5. b) Coatasome 18 probe hybridized only to two 18s (arrows) from end to end, except for the terminal regionof one chromosome 18p (arrow). c) Coatasome 5 probe hybridized to both 5s (arrows) from end to end and also hybridized to18pter (arrow). In the father with the same unbalanced rearrangement, the additional material on 18p was confirmed to be from5pter, distal to D5S23. d) Subtelomeric probes for 5 gave three 5pter signals on two 5s with 5qter signals (arrows) and on der(18)(arrow). e) Subtelomeric probes for 18 gave 18pter (arrow) and 18qter signals on one chromosome 18 and one 18qter signal withouta 18pter signal (arrow) on der(18). f) The D5S23 probe gave only two signals on 5s (arrows) and did not hybridize to der(18).

The multiple fluorescence in situ hybridizationtools available to resolve chromosome abnormali-ties warrant a strategy to contain costs. In thepresent case, a subtle 18p+ was detected (Fig.1a) and confirmed, using the coatasome 18 probe(Fig. 1b). Multicolor FISH (M-FISH) showedthat the additional material on chromosome 18was from chromosome 5 (data not shown), andwas confirmed with 5 paint (Fig. 1c). The fatherhad a similar 18p+ . The choice was to investi-gate the proband or the father. Since it was im-portant to rule out a balanced rearrangement inthe father and to determine the region of chro-mosome 5 that was involved in both, a subtelom-eric grid system was used on the father. Grid 5had three p-arm subtelomeric signals on two 5sand an 18p (Fig. 1d). Grid 18 had one p-arm

subtelomeric signal (Fig. 1e). This ruled out abalanced translocation in the father and confi-rmed a derivative 18 similar to the proband. Inrearrangements apparently involving telomeric re-gions, subtelomeric probes can characterize therearrangement, provide chromosome identifica-tion, and define p- or q-arm involvement. M-FISH or spectral karyotyping (SKY) does notprovide information regarding the chromosomearm involved; additionally, M-FISH/SKY find-ings require confirmation using paint probes, andthe resolving power of M-FISH is lower thansubtelomeric probes. Therefore, a careful assess-ment of the probe cascade that is required toresolve an abnormality and the optimum usage ofthe various FISH tools are necessary to provide acost-effective genetic diagnosis.

329

Letter to the Editor

Table 1. Summary of cryptic terminal rearrangements detected in patients having a distinctive phenotype or surveys of mentally retarded populations forsubtelomeric rearrangements or routine cytogenetic analysis

Cytogenetic result AuthorSerial no. Clinical findingsFISH result

Lamb et al. (15)Hemoglobin H (Hb H) disease,46,XY1 Proband ish der(16)t(1p;16p)(a-globin−)mat and sister had ish der(1)t(1p;16p) dysmorphic features.(a-globin+)mat. FISH with alpha globingene gave a signal on only one 16 anda second signal on distal 1p

46,XX/XY ish der(5)t(4q;5p)pat2* Overhauser et al. (16)Cri-du-chat syndromeBernstein et al. (17)ish der(5)t(5;7)(p15.3;p21)(wcp5−)mat46,XY,del(5)(p15.?2?3)3

4 46,XX ish der(4)t(4p;19p)mat using cosmid Altherr et al. (18)Wolf–Hirschhorn syndromeprobe from near the 4p telomereshowed the mother had a balanced4p;19p translocation

Reid et al. (19)Normal karyotype5 ish der(4)t(4;11)(p16.3;p15.5)(pK082−,phins 311 target 11p15.5 +)pat

6 Miller–Dieker syndromeish der(17)t(3;17)(q28;p13.1)(D17S379−) Kuwano et al. (20)46,XX,17p+ matmat. The mother had a signal forD17S379 probe from the Miller–Diekercritical region on only one 17 and asecond signal on distal 3q

46,XX ish der(17)t(8;17)(q24.3;p13.3)(D17S379−) Miller–Dieker syndrome7pat. The father had a signal forD17S379 probe from the Miller–Diekercritical region on only one 17 and asecond signal on distal 8qish der(17)t(17;19)(p13.3;q13.3) Alvardo et al. (21)8 46,XY Miller–Dieker syndrome(D17S379−)pat

46,XX,17p+ (proband) ish t(9;17)(p24.2;p13.3)(D17S379+, Kohler et al. (22)Normal, a necroscopy on an aunt9wcp17+;D17S379−, wcp9+)mat showed Miller–Dieker syndromeish der(9)t(9;17)(p24.2;p13.3)(D17S379+) Severe mental retardation and multiple46,XY (uncle)

congential abnormalitiesish der(17)t(10;17)(q26.3;p13.3)46,XX Miller–Dieker syndrome Masuno et al. (23)10(D17S379−)mat

46,XY ish der(17)t(17;20)(p13.3;q13.3)(wcp20+, Van Zelderen-Bhola etMiller–Dieker syndrome11al. (24)p17H8+,(c197-2,c197-4,c197-9)−)pat

ish t(X;17)(q24;q12)(XY527+; XY527+)46,X,t(X;17) Migeon et al. (25)12 Severe hemophilia ADe novo ish der(5)t(5;21)(p13-14;q11.2- Gill et al. (26)13 45,XY,−21 Second degree hypospadias in fetus21)(wcp 21+)De novo ish del(13)(q34)(D13S107−, Flint et al. (11)14 46,XY Mental retardation and dysmorphicMS626−) features

-do-15 46,XX routine analysis HRB De novo ish der(22)t(9;22)(rwcp der 9+46,XX, rea(22) ;4 cosmids isolated by screening chro-

mosome 22 library with MS607−)16 Developmental delay and dysmorphic Estop et al. (27)ish 46,XY,der(17)t(9;17)(q34.3;p13.3)46,XY

features(D17S34−, D17S379+, Tan1+,3AE11+,5B11−)

Multiple congentital abnormalities Smith et al. (28)17 46,XY ish der(22)t(17;22)(p13.3;q13.3)(D17S379+,D22S39−)mat

18 Blennow et al. (29)Physical anomalies, psycho-motorish der(1)t(1;15)(p36.31−33;p11.2−46,XX,1psretardation and seizures12)(wcp1−,D1Z2−,PND 12A+,

D1S160+,D1S47+)pat19 Mental retardation and dysmorphic Giraudeau et al. (30)ish del(1)(p36.3)(CEB108−)46,XY,del(1)(p36.3)

featuresPrenatal diagnosis Senger et al. (31)20 add(17)(p13) Ins(17;15)(p13;q22.3q23or24)(wcp17−,

wcp15+;wcp15−,wcp17+)Down syndrome21 Bartsch et al. (32)ish der(18)t(18;21)(q23;q22.1)(wcp21+,46,XX

DCR−,cosS55pool+, cosS359pool+,cosC9pool+)ish der(22)t(1;22)(q44;q13.32) (D22S39−) Doheny et al. (33)22 del(22)(q13.3) Developmental delay, hypotonia andmat. Mother 46,XX,t(1;22)(D22S39+; expressive language delayD22S39−)ish del(22)(q13.3q13.3)(D22S39−)23 46,XX,del(22)(q13.32)

46,XX,del(18)(p11.2) ish 46,XX,der(18)t(2;18)(p25;p11.2) Horsley et al. (7)37-year-old with mild distal spinal24atrophy, arthritis of the hands,(tel 2p+, tel 18p−)abnormal chest shape and keratosispilaris

330

Letter to the Editor

Table 1. (Continued)

Serial no. Cytogenetic result FISH result Clinical findings Author

25 Normal Familial der(4)t(4;22)(tel 4−, tel 22−) Mental retardation and dysmorphic Viot et al. (13)features

26 De novo del(2)(q37.2)27 De novo der(9)t(8;9)28 De novo der(5)t(5;11)29 46,XY,der(13)t(5;13)(q35.2;q34) 46,XY,der(13)t(5;13)(q35.2;q34). ish Proband was mentally retarded. Guichet et al. (34)

Telomeric probes were used int(5;13)(wcp13−,D13S261−; wcp5+,D5S498+) prenatal diagnosis

30–34 18q− deletion syndrome (Schinzel (1)) Brkanac et al. (35)Three interstitial deletions, two were18q−derivative chromosomes from transloca-tions of chromosome 18 with anotherunknown chromosome

35 46,XX ish del(22)(q13.3)(D22S39−, Precht et al. (36)Developmental delay, hypotonia andc106G1220−) absence of speechDe novo del(22)(q13.3)(D22S39−,46,XY36c106G1220−)

Craniofacial dysmorphism, tetralogy of Ghaffari et al. (37)37 46,XY ish der(2)t(2;17)(tel 17q+, tel 2q−)patFallot, laryngomalacia and inguinalherniaMild gross motor and speech delay, a38 46,XX ish der(4)t(4;20)(tel 4q−,tel 20p+)patsmall ventricular septal defect, minorfacial dysmorphismModerate mental handicap39 ish der(10)t(10;20)(tel 10q−, 20q+)mat46,XY

40 Reddy et al. (14)Following clinical input Albright hereditary osteodystrophy-like46,XXsyndrome46,XX,del(2)(q37.2). ish

del(2)(q37.2)(wcp2+)46,XY,del(2)(q37.2)41 ish del(2)(q37.2)(wcp2+, 2qtel−) Behavioral problems, mild mental

retardation, foot abnormalities, abnor-mal situs inversus

42 46,XY,del(8)(p23.1p23.1) ish 46,XX,del(8)(p23.1)(8ptel−)pat Developmental delay, behavioral Reddy (38)problems and atrial septal defect

Fetal 46,XX,del(8)(p23.1)pat Normal43 ish del(8)(p23.1p23.1)(wcp8+, 8ptel−)44 46,XX,add(18pter) ish der(18)t(5;18)(p15.3;p11.32)(wcp18−, Present caseLearning difficulties

wcp5+,tel18p−,tel5p+,D5S23−)pat

* Serial no. 2 was identified as t(4q;5p) in the Ledbetter paper (39).

KS ReddyJK Fugate

AcknowledgementsWe thank Andre Lubarsky for using this case to demon-strate the M-FISH SpectraVysion System (Vysis Inc).

References

1. Schinzel A. Catalogue of Unbalanced Chromosome Aber-rations in Man. Berlin, New York: de Gruyter, 1984:604–607.

2. Tonk V, Krishna J. Case report: de no6o inherited 18pdeletion in a mother–fetus pair with extremely variableexpression, confirmed by fluorescence in situ hybridization(FISH) analysis. Eur J Obstet Gynecol Reprod Biol 1997:73: 193–196.

3. Velagaleti GVN, Harris S, Carpenter NJ, Coldwell J, SayB. Familial deletion of chromosome 18(p11.2). Ann Genet1996: 39: 201–204.

4. Uchida IA, Mcrae KN, Wang HC, Ray M. Familial shortarm deficiency of chromosome 18 concomitant with arhi-

nencephaly and alopecia congenita. Am J Hum Genet1965: 17: 410–419.

5. Overhauser J, Mitchell HF, Zackai EH, Tick DB, RojasK, Muenke M. Physical mapping of the holoprosencephalycritical region in 18p11.3. Am J Hum Genet 1995: 57:1080–1085.

6. Gripp KW, Edwards MC, Mowat D, Meinecke P,Richieri-Costa A, Zackai EH, Elledge S, Muenke M. Mu-tation in the transcription factor TGIF in holoprosen-cephaly. Am J Hum Genet 1998: Suppl. 63: Abst 168.

7. Horsley SW, Knight SJ, Nixon J, Huson S, Fitchett M,Boone RA, Hilton-Jones D, Flint J, Kearney L. Del(18p)shown to be a cryptic translocation using a multiprobeFISH assay for subtelomeric chromosome rearrangements.J Med Genet 1998: 35: 722–726.

8. Zouboulis Ch C, Startakis CA, Rinck G, Wegner RD,Gollnick H, Orfanos CE. Ulerythema ophyryogenes andkeratosis pilaris in a child with monosomy 18p. PediatDermat 1994: 11: 172–175.

9. Zenger-Hain JL, Van Dyke DL, Wiktor A, Walker H,Feldman GL. Inverted duplication of chromosome5p14p15.3 confirmed with in situ hybridization. Am J MedGenet 1993: 47: 1198–1201.

10. Chia NL, Bousfield LR, Johnson BH. A case report of a deno6o tandem duplication (5p)(p14 to pter). Clin Genet1987: 31: 65–69.

331

Letter to the Editor

11. Flint J, Wilkie AO, Buckle VJ, Winter RM, Holland AJ,McDermid HE. The detection of subtelomeric chromosomalrearrangements in idiopathic mental retardation. Nat Genet1995: 9: 132–140.

12. Knight SJL, Horsley SW, Regan R, Lawrie MN, Maher EJ,Cardy DL, Flint J, Kearney L. Development and clinicalapplication of an innovative fluorescence in situ hybridiza-tion technique which detects submicroscopic rearrange-ments involving telomeres. Eur J Hum Genet 1997: 5: 1–8.

13. Viot G, Gosset P, Fert S, Prieur M, Turleau C, Raoul O,Blois De M-C, Lyonnet S, Munnich A, Vekemans M.Cryptic subtelomeric rearrangements detected by FISH inmentally retarded and dysmorphic patients. Am J HumGenet 1998: Suppl. 63: Abst 44.

14. Reddy KS, Flannery D, Farrer RJ. Microdeletion of chro-mosome sub-band q37.3, in two patients with abnormalsitus inversus. Am J Med Genet 1999: 84: 460–468.

15. Lamb J, Wilkie OA, Harris PC, Buckle VJ, LindenbaumRH, Barton NJ, Reeders ST, Weatherall DJ, Higgs DR.Detection of breakpoints in submicroscopic chromosomaltranslocations, illustrating an important mechanism of ge-netic disease. Lancet 1989: 2: 819–824.

16. Overhauser J, Bengtsson U, McMahon J, Ulm J, ButlerMG, Santiago L, Wasmuth JJ. Prenatal diagnosis andcarrier detection of a cryptic translocation by using DNAmarkers from the short arm of chromosome 5. Am J HumGenet 1989: 45: 296–303.

17. Bernstein R, Bocain ME, Cain MJ, Bengtsson U, WasmuthJJ. Identification of a cryptic t(5;7) reciprocal translocationby fluorescent in situ hybridization. Am J Med Genet 1993:46: 77–82.

18. Altherr MR, Bengtsson U, Elder FFB, Ledbetter DH,Wasmuth JJ, McDonald ME, Gusella JF, Greenberg F.Molecular confirmation of Wolf–Hirschhorn syndromewith a subtle translocation of chromosome 4. Am J HumGenet 1991: 49: 1235–1242.

19. Reid E, Morrison N, Barron L, Boyd E, Cooke A, FieldingD, Tolmie JL. Familial Wolf–Hirschhorn syndrome result-ing from a cryptic translocation: a clinical and molecularstudy. J Med Genet 1996: 33: 197–202.

20. Kuwano A, Ledbetter SA, Dobyns WB, Emanuel BS,Ledbetter DH. Detection of deletions and cryptic transloca-tions in Miller–Dieker syndrome by in situ hybridization.Am J Hum Genet 1991: 49: 707–714.

21. Alvardo M, Bass HN, Caldwell S, Jamehdor M, Miller AA,Jacob P. Miller–Dieker syndrome. Detection of a crypticchromosome translocation using in situ hybridization in afamily with multiple affected offspring. Am J Dis Child1993: 147: 1291–1294.

22. Kohler A, Hain J, Muller U. Familial half cryptic translo-cation t(9;17). J Med Genet 1994: 31: 712–714.

23. Masuno M, Imaizumi K, Nakamura M, Matsui K, Goto A,Kuroki Y. Miller–Dieker syndrome due to maternal cryptictranslocation t(10;17). Am J Med Genet 1995: 59: 441–443.

24. Van Zelderen-Bhola SL, Breslau-Siderius EJ, BeverstockGC, Stolte-Dijkstra I, de Vries LS, Stoutenbeek P, de PaterJM. Prenatal and postnatal investigation of a case withMiller–Dieker syndrome due to a familial cryptic transloca-tion t(17;20)(p13.3;q13.3) detected by fluorescence in situhybridization. Prenat Diagn 1997: 17: 173–179.

25. Migeon BR, McGinnis MJ, Antonarakis SE, Axelman J,Stasiowski BA, Youssoufian H, Kearns WG, Chung A,Pearson PL, Kazazian HG, Muneer RS. Severe hemophiliaA in a female by cryptic translocation: order and orientationof factor VIII within Xq28. Genomics 1993: 16: 20–25.

26. Gill P, Uhrich S, Disteche C, Cheng E. Fetal t(5p;21q)misdiagnosed as monosomy 21: a plea for in situ hybridiza-tion studies. Am J Med Genet 1994: 52: 416–418.

27. Estop AM, Mowery-Rushton PA, Ciepley KM, KochmarSJ, Sherer CR, Clemens M, Surti U, McPherson E. Identifi-cation of an unbalanced cryptic translocationt((9;17)(q34.3;p13.3) in a child with dysmorphic features. JMed Genet 1995: 32: 819–822.

28. Smith DP, Floyd M, Say B. Detection of a familial cryptictranslocation by fluorescent in situ hybridization. J MedGenet 1998: 33: 84.

29. Blennow E, Bui TH, Wallin A, Kogner P. Monosomy1p36.31-33�pter due to a paternal reciprocal translocation:prognostic significance of FISH analysis. Am J Med Genet1996: 65: 60–67.

30. Giraudeau F, Aubert D, Young I, Horsley S, Knight S,Kearney L, Vergnaud G, Flint J. Molecular-cytogeneticdetection of a deletion 1p366.3. J Med Genet 1997: 34:314–317.

31. Senger G, Chudoba I, Friedrich U, Tommerup N, ClaussenU, Brondum-Nielsen K. Prenatal diagnosis of a half-cryptictranslocation using chromosome microdissection. PrenatDiag 1997: 17: 369–374.

32. Bartsch O, Hinkel GK, Petersen MB, Konig U, Bugge M,Mikkelsen M, Avramopoulos D, Morris M, AntonarakisSE. A large family with subtelomeric translocationt(18;21)(q23;q22.1) and molecular breakpoint in the Downsyndrome critical region. Hum Genet 1997: 100: 669–675.

33. Doheny KF, McDermid HE, Harum K, Thomas GH,Raymond GV. Cryptic terminal rearrangement of chromo-some 22q13.32 detected by FISH in two unrelated patients.J Med Genet 1997: 34: 640–644.

34. Guichet A, Briault S, Moraine CL. High resolution chromo-some analysis and in situ hybridization of amniotic fluid fordiagnosis of a cryptic translocation. Prenat Diagn 1998: 18:399–403.

35. Brkanac Z, Cody JD, Leach RJ, DuPont BR. Identificationof cryptic rearrangements in patients with 18q- deletionsyndrome. Am J Hum Genet 1998: 62: 1500–1506.

36. Precht KS, Lese CM, Spiro RP, Huttenlocker PR, JohnstonKM, Baker JC, Christian SL, Kittikamron K, LedbetterDH. Two 22q telomere deletions serendipitously detected byFISH. J Med Genet 1998: 35: 939–942.

37. Ghaffari SR, Boyd E, Tolmie JL, Crow JL, Trainer AH,Connor JM. A new strategy for cryptic telomeric transloca-tion screening in patients with idiopathic mental retardation.J Med Genet 1998: 35: 225–233.

38. Reddy KS. A paternally inherited terminal deletion,del(8)(p23.1)pat detected prenatally in an amniotic fluidsample: A review of 8p23.1 deletion cases. Prenat Diagn1999: 19: 868–872.

39. Ledbetter DH. Minireview: cryptic translocations andtelomere integrity. Am J Hum Genet 1992: 51: 451–456.

Correspondence:Dr Kavita S ReddyCytogenetics DepartmentQuest Diagnostics Inc.33608 Ortega HighwaySan Juan Capistrano CA 92690USATel: +1 949 7284334Fax: +1 949 7284979E-mail: reddyk@questdiagnostics.com

332