Clin Genet 2009: 76: 117–119 Printed in Singapore. All rights reserved
# 2009 The Authors Journal compilation # 2009 Blackwell Munksgaard
CLINICAL GENETICS doi: 10.1111/j.1399-0004.2009.01170.x
Letter to the Editor
HDR (Hypoparathyroidism, Deafness, Renal dysplasia) syndrome associated to GATA3 gene duplication To the Editor: GATA3 haploinsufficiency due to loss-of-function mutations or deletions is the only known pathogenic mechanism causing HDR (Hypoparathyroidism, sensorineural Deafness, Renal dysplasia) triad (OMIM #146255) (1, 2). Mutations in regulatory sequences and genetic heterogeneity could explain the small subset of HDR syndrome patients negative to GATA3 screening (1–3). We report on a girl presenting HDR triad associated with psychomotor delay, facial dysmorphisms, bilateral cleft lip and palate, heart defect and abnormal fingers and toes, resulting from a complex rearrangement of 10p15p14 region. She was the firstborn of healthy non-consanguineous parents. Pregnancy was complicated by growth retardation. A prenatal ultrasound scan at 20 weeks detected unilateral renal hypoplasia. Amniocentesis disclosed a 46,XX karyotype. She was born by cesarean section at 36 weeks of gestation. Birth weight was 2490 g (3rd centile), length 49 cm (50th centile), and head circumference 32.5 cm (,3rd centile). Apgar scores were 9 and 10 at 1 and 5 min. Mild hypocalcemia (7.5 mg/dl; normal range: 8.8–10.8 mg/dl) was diagnosed on the third day of life. Clinical examination disclosed high-arched and sparse eyebrows, synophrys, hypertelorism, upslanting palpebral fissures, bilateral cleft lip and palate (Fig. 1a), tapering fingers, and malposed toes with cutaneous syndactyly of second and third toes. Cerebral ultrasound revealed bilateral subependymal hemorrhage and asymmetric lateral ventricles; echocardiography showed Tetralogy of Fallot; renal ultrasound confirmed left kidney hypodysplasia with hyperechogenic parenchyma and cortical microcysts and right pyelic ectasia; cystoureterography demonstrated second-grade left vesicoureteral reflux; acoustic otoemission testing disclosed bilateral deafness. At 14 months, her weight was 11.9 kg (90th centile), height 81 cm (90th–97th centile) and head circumference
45.5 cm (25th centile). Developmental milestones were mildly delayed. Subtelomeric regions fluorescence in situ hybridization (FISH) analysis (ToTelVysion Kit; Abbott Molecular, Abbott Park, IL) disclosed 10pter de novo deletion, which was further characterized by array-comparative genomic hybridization (44K Chip; Agilent Technologies, Waldbronn, Germany). This analysis confirmed 10p15.3p15.1 deletion spanning about 6.5 Mb, from A_14_P134493 (138,206 bp) to A_14_P107348 (6,561,124 bp) probes, and detected 10p15.1p14 duplication spanning 1.9 Mb, from A_14_P107636 (6,639,966 bp) to A_14_P124746 (8,457,497 bp), based on May 2004 release mapping data (hg17; http://www. ensembl.org) (Fig. 1b). Both were de novo imbalances not listed among copy number polymorphisms (http://projects.tcag.ca/variation/). Break points were confirmed by dual-color FISH, using BAC clones (32K Library; BACPAC Resources, Oakland, CA), and real-time polymerase chain reaction (PCR) assays (Fig. 2). The rearrangement likely originated by the breakage–fusion–bridge step (4), but no evident genomic architectural feature possibly underlying this mechanism mapped nearby the break points. The duplicated segment included GATA3 and 1.5 Mb upstream and 0.3 Mb downstream of this gene (Fig. 2b). Real-time PCR assay confirmed a twofold increase in the GATA3 copy number compared with parents’ and three healthy controls’ DNAs (data not shown). Complementary DNA direct sequencing did not disclose any alteration in GATA3 sequence. The present observation suggests that both GATA3 deletion and duplication could lead to a similar phenotype. This mechanism has been demonstrated for other transcription factors involved in developmental control processes, in agreement with the Ôbalance hypothesis’ (5–12). Indeed, several studies in mouse have shown a direct relationship between organogenesis and GATA3 expression levels with a temporal and 117
Letter to the Editor Fig. 1. (a) The patient at birth showing high-arched and sparse eyebrows, synophrys, hypertelorism, upslanting palpebral fissures and bilateral cleft lip and palate. (b) Array-comparative genomic hybridization analysis shows that the deleted 10p15.3p15.1 segment is preceded by a duplication within 10p15.1p14 region.
tissue-specific fine-regulated gene expression (13, 14). Interestingly, a mosaic 10p inverted duplication was recently reported in a fetus with right renal pelvis dilatation and bilateral cleft lip and palate (15). In addition to HDR triad, our patient showed developmental delay, facial dysmorphisms, cleft lip and palate, heart defect and fingers’ and toes’ anomalies. These features were reported in HDR patients with terminal and/or interstitial 10p deletions including the 10p14p13 DiGeorge syndrome locus 2 (DGS2) (16). Although this region was not rearranged in the
present patient, we cannot exclude an effect of the inverted duplication on the chromatin architecture and the downstream genes expression. However, Tetralogy of Fallot could be also related to GATA3 duplication as Gata3 binds to Pparbp in mouse, this latter protein being crucial for the development of several organs, including heart (17). The unbalanced segment includes 40 additional RefSeq genes (UCSC; www.genome. ucsc.edu) (Fig. 2b). Although none of them appears obviously related to the observed phenotype, their possible role deserves further
Fig. 2. (a) The dual-color fluorescence in situ hybridization (FISH) analysis, performed on patient’s nuclei and metaphases with 10p14 locus-specific clones, shows that the hybridization pattern is consistent with the presence of an inverted duplication. (b) Detail of 10p15.3p14 region showing GATA3 (red) position with respect to the imbalances. The size of the deletion (green arrow) and the duplication (red arrow) is confirmed by FISH analysis. RP11-774G8 clone straddles the deleted and the duplicated regions and shows a normal pattern of hybridization, suggesting that it is partially deleted and partially duplicated and contains the break point. (c) Break point is located in the PRKCQ sequence (gray): IVS1 (red line) and IVS14 (green line) have been amplified, and real-time polymerase chain reaction (RT-PCR) results showed the IVS1 duplication (red histogram on the right) and IVS14 deletion (green histogram on the left). TERT was used as reference gene, and the results have been analyzed by the 22DDCt method (18).
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Letter to the Editor
investigation. The present patient with HDR syndrome associated with GATA3 duplication suggests that duplication or undetected mutations enhancing GATA3 expression could explain part of the molecularly uncharacterized HDR patients.
Acknowledgement This work was supported in part by a grant from the Italian Ministry of Health (Ricerca Corrente 2008) and a grant from the National Institutes of Health (ÔItaly-USA Program’ – Rare Diseases).
L Bernardinia L Sinibaldia,b A Capalboa I Bottilloa,b B Mancusoa,b B Torresa,b A Novellia MC Digilioc B Dallapiccolaa,b a IRCCS-Casa Sollievo della Sofferenza, San Giovanni Rotondo and CSS-Mendel Institute, Rome, Italy, bDepartment of Experimental Medicine, Sapienza University, Rome, Italy, and c Medical Genetics, Bambino Gesu` Hospital, IRCCS, Rome, Italy
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