Downloaded from jmg.bmjjournals.com on 9 March 2006 Nijmegen breakage syndrome (NBS) with neurological abnormalities and without chromosomal instability E Seemanová, K Sperling, H Neitzel, R Varon, J Hadac, O Butova, E Schröck, P Seeman and M Digweed J. Med. Genet. 2006;43;218-224; originally published online 20 Jul 2005; doi:10.1136/jmg.2005.035287 Updated information and services can be found at: http://jmg.bmjjournals.com/cgi/content/full/43/3/218 These include: References This article cites 29 articles, 7 of which can be accessed free at: http://jmg.bmjjournals.com/cgi/content/full/43/3/218#BIBL Rapid responses You can respond to this article at: http://jmg.bmjjournals.com/cgi/eletter-submit/43/3/218 Email alerting Receive free email alerts when new articles cite this article - sign up in the box at the service top right corner of the article Topic collections Articles on similar topics can be found in the following collections Genetics (3709 articles) Notes To order reprints of this article go to: http://www.bmjjournals.com/cgi/reprintform To subscribe to Journal of Medical Genetics go to: http://www.bmjjournals.com/subscriptions/ Downloaded from jmg.bmjjournals.com on 9 March 2006 218 ORIGINAL ARTICLE Nijmegen breakage syndrome (NBS) with neurological abnormalities and without chromosomal instability E Seemanova´, K Sperling, H Neitzel, R Varon, J Hadac, O Butova, E Schro¨ck, P Seeman, M Digweed ............................................................................................................................... J Med Genet 2006;43:218–224. doi: 10.1136/jmg.2005.035287 Background: Nijmegen breakage syndrome (NBS) is an autosomal recessive chromosomal instability disorder with hypersensitivity to ionising radiation. The clinical phenotype is characterised by congenital microcephaly, mild dysmorphic facial appearance, growth retardation, immunodeficiency, and greatly See end of article for increased risk for lymphoreticular malignancy. Most NBS patients are of Slavic origin and homozygous for authors’ affiliations the founder mutation 657del5. The frequency of 657del5 heterozygotes in the Czech population is 1:150. ....................... Recently, another NBS1 mutation, 643C.T(R215W), with uncertain pathogenicity was found to have Correspondence to: higher frequency among tumour patients of Slavic origin than in controls. This alteration results in the Professor M Digweed, substitution of the basic amino acid arginine with the non-polar tryptophan and thus could potentially Institute of Human interfere with the function of the NBS1 protein, nibrin. Genetics, Charite´- Universita¨tsmedizin Berlin, Methods and Results: Children with congenital microcephaly are routinely tested for the 657del5 mutation Augustenburger Platz 1, in the Czech and Slovak Republics. Here, we describe for the first time a severe form of NBS without 13353 Berlin, Germany; chromosomal instability in monozygotic twin brothers with profound congenital microcephaly and martin.digweed@charite. developmental delay who are compound heterozygotes for the 657del5 and 643C.T(R215W) NBS1 de mutations. Both children showed reduced expression of full length nibrin when compared with a control Revised version received and a heterozygote for the 657del5 mutation. Radiation response processes such as phosphorylation of 19 July 2005 ATM and phosphorylation/stabilisation of p53, which are promoted by NBS1, are strongly reduced in Accepted for publication cells from these patients. 20 July 2005 Published Online First Conclusions: Interestingly, the patients are more severely affected than classical NBS patients. 20 July 2005 Consequently, we postulate that homozygosity for the 643C.T(R215W) mutation will also lead to a, ....................... possibly very, severe disease phenotype. ijmegen breakage syndrome (NBS) is an autosomal heterozygosity, 657del5/643C.T(R215W), of the twin recessive chromosomal instability disorder charac- brothers is the primary cause of their clinical phenotype Nterised by congenital microcephaly, growth retarda- which seems to be more severe than the classical form of tion with pre- or postnatal onset, immunodeficiency, NBS. hyperradiosensitivity, and cancer predisposition.12 Most NBS patients are of Slavic origin and are homozygous for Clinical report 2–4 the founder NBS1 mutation 657del5. Congenital micro- The propositi, monozygotic twin boys (JR and PR), were born 2 cephaly is a hallmark of NBS and could be used, together to a 27 year old primigravid mother and a 29 year old father. with the identification of the responsible NBS1 mutations, as The couple is healthy, non-consanguineous, non-endogam- signal criteria for an early diagnosis of NBS in the Czech and eous, and had no contributory family history. Slovak Republics. Recently, we showed that the proportion of The pregnancy was uncomplicated until the 31st+1 week NBS patients among Czech infants with congenital micro- of gestation when fetal ultrasound examination showed an cephaly was 13%. In the Slovak Republic, this incidence was abnormal head shape and growth retardation of both fetuses. found to be as high as 50% among infants with both Two weeks later oligohydramnion occurred in one of the microcephaly and increased chromosomal instability.56 twins after amniotic fluid disruption; the next day both Among infants with primary microcephaly, screened for the children were spontaneously delivered head first. 657del5 mutation, we diagnosed monozygotic twin brothers Twin A, a boy (PR; fig 1A), was born after 33+1 weeks at the age of 2 months to be heterozygous for this mutation. gestation with an Apgar score of 7-9-9. His birth weight was The severe congenital microcephaly and hypotrophy were 1520 g, length was 40 cm, and OFC was 26 cm. Immediately indications for further analysis of the NBS1 gene. Another after birth, an abnormal skull shape with a small anterior NBS1 mutation, namely 643C.T(R215W), was detected on fontanel (0.560.5 cm), without a small fontanel, and with the second allele of the twin brothers. This mutation has been synostosis of coronal and sagittal sutures, was noted. The previously described in patients with acute lymphoblastic sutura metopica was prominent, occiput was flat, and the leukaemia,7 non-Hodgkin’s lymphoma,8 and at a high skull developed a microturricephalic shape. Ultrasound frequency among tumour patients of Slavic origin.9 Further investigation after birth showed enlarged, mild asymmetric clinical investigations of the children revealed partial lateral ventriculus, enlarged subarachnoidal areas (4 mm), lissencephaly and epileptic seizures, and respiratory and feeding problems were also noted. Based on the clinical Abbreviations: IR, irradiation; LCL, lymphoblastoid cell line; NBS, and molecular findings, we propose that the compound Nijmegen breakage syndrome; SKY, spectral karyotyping www.jmedgenet.com Downloaded from jmg.bmjjournals.com on 9 March 2006 Nijmegen breakage syndrome 219 and poor gyrification of the brain. No signs of intraventricular METHODS bleeding were found. Phototherapy was applied at 5 days Mutation analysis because of icterus. Enteral feeding was administered for the DNA was isolated from peripheral blood and lymphoblastoid first 5 days, but after that the child was breast fed and could cell lines (LCLs) were established according to standard be discharged home at the age of 33 days with 2095 g weight, procedures. Informed consent was obtained from the parents 43 cm length, and OFC 29.8 cm (all parameters below the of the children analysed in this study. Because of their third percentile, OFC very low, corresponding to 3 s). PR congenital microcephaly and Slavic origin, both children showed mild muscle hypertonia and brisk reflexes particu- were tested for the NBS1 mutation 657del5 at the age of larly involving the legs. A first attack of myoclonic seizures 2 months. The mutation analysis was carried out as was documented at the age of 3 months and progression to previously described5 and it was found that both children status epilepticus at 5 months was rapid. During his stay in were heterozygous for the Slavic mutation. In an attempt to the neurology clinic, he received medication for the status find a second mutation, further analysis of the NBS1 gene epilepticus and improved, but some 15 seizures per day were was carried out. The DNA samples were analysed by PCR common and feeding per sonda was necessary. Feeding and amplification and sequencing of NBS1 exons and flanking respiratory problems were progredient and therefore gastro- intronic sequences on an ABI 3100 DNA Analyzer (Applied stomy was necessary at the age of 7 months. Psychomotor Biosystems, Foster City, CA). development was severely retarded and correlated with development in infants in the first trimenon. OFC at the Western blot analysis age of 1 year was 37.6 cm, weight was 8750 g, and length Proteins were isolated from LCLs of both patients according was 69 cm (third percentile except for OFC, which corre- to standard procedures and examined in comparison with sponded to 25 SD). The child was last seen at the age of control cells and cells heterozygous for the 657del5 or 15 months and his somatic development due to feeding by 643C.T(R215W) mutation. Blots were probed with a rabbit gastrostomy and despite rare respiratory problems was polyclonal antibody (Novus Biologicals, Littleton, CO) direc- satisfactory (9500 g weight, 74 cm length, OFC 39 cm). His ted against the C-terminal portion of nibrin. Antibodies microturricephaly with prominent