Bilateral retinoblastoma associated with 13q− mosaicism

Bilateral retinoblastoma associated with 13q− mosaicism

Bilateral Retinoblastoma Associated with 1 3 q - Mosaicism Possible Manifestation of a Germinal Mutation Maria Cecilia Menks Ribeiro, Joyce Anderson D...

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Bilateral Retinoblastoma Associated with 1 3 q - Mosaicism Possible Manifestation of a Germinal Mutation Maria Cecilia Menks Ribeiro, Joyce Anderson Duffles Andrade, Clelia Maria Erwenne, and Decio Brunoni

ABSTRACT: Fifteen retinoblastoma patie~ts were studied cytogenetically using G- and R-banding techniques. One patient showed 13q- mosaicism. It is suggested that a postzygatic deficiency in mosaic cases and in tumoral cells may be secondary to germinal mutation.


Human retinoblastoma is the most c o m m o n intraocular eye tumor of ch i l d h o o d and is considered to be a prototype of dew,~lopmental tumors. A predisposition to dev el o p m en t of retinoblastoma is associated with the mutation of the retinoblastoma gene locus, w h i c h has been mapped to c h r o m o s o m e band 13q14. or with a constitutional c h r o m o s o m e deletion affecting the same region. In the inherited cases. transmission follows an autosomal dominant trait. In some systematic surveys using high-resolution c h r o m o s o m e techniques, the frequency of detectable rearrangements is probably of the order of 10% [1]. Today there are several models that have been proposed to explain the origin of retinoblastoma, taking into account the different etiologic backgrounds and the variability of manifestations of this type of tumor [2]. The present article is a systematic investigation of 15 patients with retinoblastoma. A 46,XY/46,XY,del (13)(q12.3q21.2) mosaicisin was found in one patient. PATIENTS

Patients were referred to us by the Section of Ophthalmology of the Hospital A.C. ('amargo. The patients had either not received any radiochemotherapy or had stopped this treatment at least 6 months earlier. Family history and other family information were obtained by interviews. From the Dist:iplina de Gen(:rticada Escola Paulista de Medicina. Sho Paulo {M. C. M. R.. I. A. D., D. B.} and the Serviq:ode Oftalmologia do Hospital A. C. Camargo {C. M. E.}. Brazil. Address request for reprints to: Maria Cecilia Menks Ribeiro, l)isciplina de Gen~tica. Escola Paulista de Medicina, Caixa Postal 20.363, 04034 S(~t~ Paulo-SP. Brazil. Received June 22, 1987; accepted November 2. 1987.

169 ~, 1988 Elsevier Science Publishing Co., Inc. 52 Vanderbilt Ave.. New York. NY 10017

Cancer (;enet Cytogenet 32:169-175 [198,q) 0165-4608.,'88,'$03.50


M . C . M . Ribeiro et al.

CYTOGENETIC STUDIES Lymphocyte cultures were routinely performed in RPMI 1640 m e d i u m with 20% calf serum added, and chromosome studies were performed by G-banding [3], Qbanding [4], and a modification of R-banding using 50 v.g/ml of BrdU during the last 7 hours of culture. Slides were treated with Na2HPO4 at 89°C and stained with Giemsa [5]. GENERAL CHARACTERISTICS OF THE PATIENTS Fifteen patients were studied. General patient data are s u m m a r i z e d in Table 1. Age at diagnosis of retinoblastoma ranged from 5 to 50 months, and age at referral to us ranged from 5 months to 37 years. The tumor was unilateral in nine cases; four of these patients were females and five were males. The remaining six patients (two males and four females) had bilateral retinoblastoma. Parental age at birth ranged from 22 to 48 years. Six patients had a family history of cancer (cases 7, 9, 10, 11, 14, and 15). The mother of case 13 has used anticonvulsants during pregnancy. The fathers of patients 2, 5, 8, 9, and 14 and the mother of cases 10 and 11 were professionally exposed to chemical products at the time of conception. FAMILY HISTORY Patients 9, 14, and 15 had hereditary retinoblastoma. Patient 9 had two sons with bilateral retinoblastoma. Patients 14 and 15 (mother and daughter) had bilateral and unilateral retinoblastoma, respectively. Patients 10 and 11 were monozygotic twins (p -- 0.8201). The other patients had no history of retinoblastoma in the family. CHROMOSOMAL ANALYSIS Chromosome analysis gave normal results in 14 patients. One patient had a 46,XY/ 46,XY,del(13)(ql 2.3q21.2) karyotype. This patient (case 8) is reported in detail below. CASE REPORT The patient was a white male born on January 24, 1980, following a full-term pregnancy, u n c o m p l i c a t e d labor, and vertex delivery to an 18-year-old gravida 2, para 2, abortus 0 mother and a 26-year-old unrelated father. There was no k n o w n exposure to toxins, x-rays, drugs, or infections. Apgar scores were not recorded, but the newborn had good vitality with normal crying. Birthweight was 3.6 kg. No anoma+ lies were noted. Major developmental delay was apparent early. Bilateral retinoblastomas were diagnosed at 6 months of age (Reese stage I on the right and extraocular class 2 on the left). The left eye was enucleated, and chemo/radiotherapy and photocoagulation were performed with good results. An EEG showed a diffuse irritating activity. Two sisters were healthy and family history was negative for retinoblastoma, birth defects, or genetic disorders. At age 3 years the patient exhibited good general health, normal vital signs, and severe psychomotor retardation: he was able to stand only with support, did not vocalize, and c o m m u n i c a t e d only by gestures. His height was 90 cm [below 3%); weight: 14 kg (25%); occipitofrontal circumference (OFC): 47 cm (3%). The facies was impressive for the absence of the left eye, and craniofacial d y s m o r p h i s m was observed i n c l u d i n g hirsutism, bitemporal hollowing, p r o m i n e n t eyebrows, down-

3103 3196 3201 3146 3232 3237





1929 3301 3370



1 2 3 4 5 6





11 12 13














13 22 25





27 31 33 50 22 24

A b b r e v i a t i o n s : U = u n i l a t e r a l B = bilateral.

Laboratory number

Age at diagnosis (months) yr yr yr yr yr yr 3 mo 9mo 2 mo

7 mo 4 mo

31 yr 5mo

19 yr 5 yr 2 yr 1 mo

19 yr

37 yr

2 yr 5 mo

7 yr 11 mo

3 5 10 4 3 2

Age at cytogenetic studies

General information about patients


Table 1









Tumor form



22 32 25





28 20 21 20 24 28




27 25 48





34 22 26 25 22 30


Parental age at birth (yr)



46,XX 46,XY 46,XX


46,XY/ 46,XY,del(13) 46,XY


46,XX 46,XX 46,XY 46,XX 46,XY 46,XY


Maternal aunt

Rb in two s o n s and cancer in the paternal grandfather Maternal aunt

Paternal grandfather

Cancer in family

Minor phenotypic signs Use o f anticonvulsives during pregnancy Mother and daughter (cases 14 and 15)

Monozygotic t w i n s (cases 10 and 11)

Maternal g r a n d m o t h e r had 10 s p o n t a n e o u s abortions Rb appeared after cranial traumatism




M . C . M . Ribeiro et al.

Figure 1 Patient 8, frontal view. slanting of the right palpebral fissure, broad nasal bridge, bulbous tip of the nose, long philtrum, retrognathia, and large ears (6 cm: 75-90%) (Fig. 1). The dermatoglyphic patterns were normal: palmar and finger creases, ten whorls, triradius at t position on the left and t' on the right with an ulnar loop in this h y p o t h e n a r area. Cytogenetic studies were performed on three separate occasions when the patient was aged, respectively, 2 years 6 months (July 1982), 3 years 9 months (October 1983), and 5 years 4 months (May 1985). The karyotype was 46,XY/46,XY, del (13)(q12.3q21.2) (Fig. 2). The proportion of abnormal cells was 85%, 65%, and 80%, respectively, at each visit. The karyotypes of his parents and sisters were norreal. DISCUSSION Various chi'omosomal rearrangements are liable to produce retinoblastoma through involvemei~t of 13q14. The most frequent rearrangements are de novo interstitial deletions. They are of variable length, the smallest region of overlapping being the proximal half of band q14 [6, 7]. Their frequency is probably of the order of 80% to 90% of all cytogenetic forms [1]. To date; 12 cases of mosaicism for 13q14 deficiency have been reported (Table 2), most of them as the result of systematic studies I10, 11. present easel. Most patients with 13q- deficiency show heterogeneous p h e n o t y p i c manifestations, with the frequent presence of various degrees of meutal and developmental retardation. Most investigators believe that the variation in p h e n o t y p i c manifestations is the consequence of the involvement of different regions of chromosome 13 adjacent to the q14 band, and of the extent of the deleted fragments [10, 151. Motegi et al. [16] suggested that there may be a recognizable pattern of changes in the midface area associated with a deletion of 13 (q12q22). This index was based upon their study of three patients with retinoblastoma whom they characterized as having prominent eyebrows, broad nasal bridge, bulbous tip of the nose, a large mouth with a thin upper lip, and a long philtrum. They thought that this facial


Bilateral Retinoblastoma and 13q- Mosaicism


B 13


,2 11.2 11.1 1i

12.2 12.3 13



I/-..3 21.1


21.2 21.3 22




tl W

]3 14




Figure 2 Chrom()somes of patient 8. (A) Ideogram defining the' localization and extent of del(13)(q12.3q21.21. (B) Partial karyotype showing the normal 13 (h;ft) and de,l (13) chromosome (right).

pattern was present in published photographs of patients as ",,,,ell. Our patient also presented these facial characteristics. Motegi and Minoda [13] observed a significant decrease in the proportion of 13q14 deleted cells in three retinoblastoma patients with 13(:114 deletion mosaicism when they were reexamined. The same observation was mad(,, by (.)rye et al. [12]. We observed a significant de(:rease of 13q14 deleted cells in the seconlt culture, but in the third culture the proportion of abnormal cells was similar to the first one. Even though the nature of the mutation responsible for retinoblastoma is not known, we observed that the parents of eight palients were exposed to chemical produ(:ts at the time of conception. A similar association was indicated by Wilkins and Sinks [17], who reported a correlation between occupation exposure of the parents to lead and hydrocarbons and the occurrence of Wihns' tumor in their descendant.s. Cases of 1 3 q - mosaicism provide evidence for the existence of two steps in the process of retinoblastoma development. Of the 12 cases reported, eight are bilate,ral. Because ml)saicism is a postzygotic event, for bilateral cases we may assume the presenl:e of a germinal (genie) mutation that may caus(; the region to be susceptible to breaks. Evidence of this type has been provided by Dudin et al. [14l, who observed 13(I - mosai(:ism in a patient with bilateral retinoblastoma whose affected parent was cytogene, tically normal. Recent studies of fragile chromosome sites have reported a fragile site located on



Table 2

Ribeiro et al.

P u b l i s h e d cases of r e t i n o b l a s t o m a and 13q - m o s a i c i s m Mental Phenotyt}i{: Retinoblastoma re.tardation signs

Re.fercn(:e Taylor I81 Sl)arkes ct al. [9]

B kl

Motegi [101 {11 (2) Motegi [11] (1} {2} {3} Orye et al. I12] Motegi and Minoda [13[ I}udin et al. [14] Ward et al. [7I Present case











+ )

B l.]






Frequen{:y of abnormal (:ells

Breakpoint Unidentified {114--,q22 (t14.1~q14.3 (114.1 --,ql 4.3 q14.1--,q14.3 q14.1-~.ql 4.3 {113.1~q14.3

Not reported Nornlal lymphocyt{:s 100% tihroblasts 5% 9% 6% 1 1%-zero ~' 63%-I{}%b



q14.1~14.3 (Joidentifie(l {113.1~q14.11 (I12.3-~q21.2

5% 93% 85%-65% -80%"


- 1{}%"

Abbreviations: " Fr~quen(.:ies obserw,'d on different occasiolls. " se(:ond o b s e r v a t i o n by" Motegi a n d M i n o d a [13]. U

unilaterak B


13q14 band [18, 19]. T h e h y p o t h e s i s of a fragile site on the 13q14 band as the original m u t a t i o n in patients w i t h r e t i n o b l a s t o m a may e x p l a i n the c h a n g e s in chrom o s o m e 13 o c c u r r i n g in t u m o r cells. A c c o r d i n g to Potluri et al. [20], these changes are present in 21% of both h e r e d i t a r y and s p o r a d i c tumors. A study by Yunis and Soreng 121] has d e m o n s t r a t e d that the breakpoints of the t r a n s l o c a t i o n s present in sew.~ral types of t u m o r s c o i n c i d e w i t h the location of s p o n t a n e o u s and i n d u c e d fragile sites and oncogenes. In contrast to p r e v i o u s beliefs, changes in c h r o m o s o l n e 13 m a y not be related only to the d e v e l o p m e n t of r e t i n o h l a s t o m a as they h a v e heen o b s e r v e d in preleukemic i n d i v i d u a l s w h o s h o w e d o t h e r c h r o m o s o m e alterations in a d d i t i o n to 13q-[22] and have been o c c a s i o n a l l y r e p o r t e d to be present in o t h e r t u m o r s s u c h as s q u a m o u s cell c a r c i n o m a [23], o s t e o s a r c o m a , and m y e l o p r o l i f e r a t i v e s y n d r o m e s ]24]. On this basis, we may a s s u m e that band 13q14 has a c a r c i n o g e n i c potential that is not l i m i t e d to the retina, in a g r e e m e n t w i t h the i n c r e a s e d i n c i d e n c e of other u e o p l a s i a s o b s e r v e d in r e t i n o b l a s t o m a patients and their relatives [1, 25]. T h e dev e l o p m e n t of more than one n e o p l a s i a has also been o b s e r v e d in familial c a n c e r [261. T h e study of fragile sites in r e t i n o b l a s t o m a patients and their relatives may elu(:(date the r e l a t i o n s h i p b e t w e e n a fragile site and retinohlastoma. Research supported by Funda{,:8o de Amparo a Pesquisa do Estado de Silo Paulo (I"APESP} and Conselho National de Desenvolvimento Cientifico e Te(:nol6gico [CNPq).


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