NPHP3 Mutations Are Associated with Neonatal Onset Multiorgan Polycystic Disease in Two Siblings

PERINATAL/NEONATAL CASE PRESENTATION NPHP3 mutations are associated with neonatal onset multiorgan polycystic disease in two siblings

KT Leeman1,2,3, L Dobson4, M Towne3,4, D Dukhovny5, M Joshi1,3,4, J Stoler4 and PB Agrawal1,3,4

Two siblings with a severe multiorgan polycystic disease presenting in the neonatal period were identiﬁed. Their genetic testing identiﬁed compound heterozygous NPHP3 gene mutations, parents being heterozygous carriers. The mutations included a splice- site (c.958-2A4G) and a missense mutation (c.2342G4A; p.G781D), both being extremely rare. NPHP3 encodes for nephrocystin 3 present on the cilia-centrosome complex. We hypothesize that these mutations lead to defective cilia-based signaling, required for normal development of the renal, pancreatic, biliary and portal system. This report outlines a rare neonatal ciliopathy presentation of NPHP3 mutations leading to severe multiorgan failure in two siblings.

Journal of Perinatology (2014) 34, 410–411; doi:10.1038/jp.2014.20 Keywords: polycystic kidney disease; ciliopathy; nephronophthisis; NPHP3

INTRODUCTION failure with anuria and a peritoneal dialysis catheter was placed. Ciliopathies are a genetically heterogeneous group of disorders He developed acholic stools and underwent a workup including caused by defects in the cilium-centrosome complex.1 Primary an abnormal magnetic resonance cholangiopancreatography non-motile cilia are microtubule-based structures, located on most showing dilated biliary ducts without obstruction. vertebrate cells and are highly conserved throughout evolution.2 His clinical status deteriorated in the setting of presumed sepsis Primary cilia function as complex sensory organelles involved in with multiple organ failure, profound hypotension resistant to cellular signaling and are critical for the normal function of dopamine and epinephrine, hypoxia and bradycardia. The family multiple organ systems.1 A constellation of single-gene defects in opted for no further escalation of medical technology, and he died the cilium-centrosome complex have been identified and shown at 3 months of age. to lead to ciliopathies with multiorgan involvement.3 Postnatal genetic testing included a repeat karyotype that was In this report, we describe two siblings who presented with normal (46, XY), and a normal chromosomal microarray. Based on severe multiorgan cystic disease in the neonatal period. After the age of presentation and the constellation of clinical findings, extensive genetic testing including sequencing several candidate several candidate genes were sequenced during his neonatal genes, two novel NPHP3 mutations were identified that segre- intensive care unit stay with no pathogenic variant identified. gated in the parents. These included INVS and NEK8 that are mutated in infantile presentations of polycystic kidney disease.1 Several additional candidate genes associated with nephronophthisis were CASE sequenced after his death. One of those sequenced candidate A 28-year-old gravida 2, para 1 female presented to obstetric care genes was NPHP3 that encodes for nephrocystin 3. Sequencing of at 20 weeks gestation with an abnormal fetal ultrasound showing NPHP3 revealed two novel mutations, a paternally inherited bilaterally enlarged echogenic kidneys. The parents were not acceptor splice-site mutation, c.958-2A4G and a maternally consanguineous, and the mother and father had a previous inherited missense variant c.2342G4A postulated to cause the healthy child. An amniocentesis was performed that revealed a amino-acid substitution p.G781D, a highly conserved residue in normal male karyotype (46, XY) and the FISH for 22q11.2 deletion vertebrates. These mutations were predicted to be pathogenic 4 5,6 was normal. A fetal MRI performed at 30 weeks gestation noted by Polyphen-2, SIFT (sorting intolerant from tolerant) and 7 situs inversus totalis, bilaterally enlarged multicystic kidneys, no MutationTaster software. NPHP3 mutations are associated with a visible amniotic fluid and hypoplastic lung tissue (Figure 1a). An broad spectrum of early embryonic defects, including situs upper abdominal oblong cystic structure, postnatally identified as inversus and multicystic kidneys with a wide age range of 8,9 the pancreas, was also visualized. presentation. While awaiting results from the candidate genes Premature birth resulted from spontaneous labor at 32 6/7 testing sent after his death, the family was also enrolled in an weeks of gestation. On initial postnatal imaging studies, prenatal institutional review board-approved research protocol, and the diagnoses were confirmed, including: situs inversus totalis, large patient’s DNA was sent for whole-genome sequencing (WGS). The polycystic kidneys and large pancreatic cysts (Figure 1b). His WGS data were obtained after the identification of NPHP3 degree of pulmonary hypoplasia required intubation with mutations and therefore were not analyzed, but both mutations mechanical ventilation throughout his course. He developed renal were present in that data.

1Division of Newborn Medicine, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA; 2Harvard Stem Cell Institute, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA; 3The Manton Center for Orphan Disease Research, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA; 4Division of Genetics and Genomics, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA and 5Division of Neonatology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA. Correspondence: Dr KT Leeman or Dr PB Agrawal, Division of Newborn Medicine, Boston Children’s Hospital, Harvard Medical School, 300 Longwood Ave, Hunnewell 4, Boston, MA 02115, USA. E-mail: [email protected] or [email protected] Received 29 October 2013; revised 10 January 2014; accepted 13 January 2014 NPHP3 mutations in neonatal onset multiorgan polycystic disease KT Leeman et al 411 severe adolescent presentation, a pattern supported by mouse studies of Nphp3 defects.9,11,12 A rare neonatal presentation is seen in our siblings. Two previous case reports have described neonatal presentations of NPHP3 gene mutations leading to different presentations of multiorgan cystic disease, one with homozygous nonsense mutation c.1729C 4T (p.Arg577X) in exon 11 of the NPHP3 gene9 and the other with homozygous deletion of the conserved splice acceptor dinucleotide (AG) preceding exon 20 in the NPHP3.13 Recent work has utilized high-throughput mutation analysis to identify additional novel mutations leading to defects in NPHP3, with a higher percentage of infant presentations Figure 1. MRI studies in the proband showing cysts present in than previously described.14,15 bilateral kidneys and pancreas. (a) Prenatal MRI demonstrating In summary, this report outlines a rare presentation of NPHP3- polycystic kidney and bell-shaped pulmonary hypoplasia. (b) associated ciliopathy in the neonatal period. We suggest that when Postnatal MRI showing bilateral polycystic kidneys and cystic pancreas. available, a gene panel should be used to identify the genetic basis Arrow heads, polycystic kidneys; arrows, bell-shaped hypoplastic for a highly heterogeneous disorder such as a ciliopathy. If such a lungs; star, cystic pancreas. panel is not available, approaches such as whole-exome or -genome sequencing may be preferable to single-candidate gene sequencing A sibling of the proband was spontaneously conceived and for rapid turnover, lower costs and to alleviate parental anxieties. prenatal imaging included a 31-week gestation MRI showing Further, clinicians should consider genetic testing for ciliopathies in polycystic kidneys, multiple pancreatic cysts and severe oligohy- neonates presenting with cysts in multiple organ systems. dramnios with pulmonary hypoplasia. The family declined amniocentesis or maternal-free fetal DNA testing for the known familial mutations. The infant was delivered vaginally following CONFLICT OF INTEREST labor induction at 34 4/7 weeks due to severe oligohydramnios The authors declare no conflict of interest. and risk of cord compression. Her postnatal imaging confirmed bilateral polycystic kidneys, multiple pancreatic cysts and several hepatic cysts. She also had severe pulmonary hypoplasia requiring ACKNOWLEDGEMENTS mechanical ventilation and elevated direct bilirubin suggestive of This work was funded by a grant from The Manton Center for Orphan Disease a bile duct abnormality, although no definitive high-resolution Research. imaging was performed. Her multiorgan involvement was similar to the proband, except that she had situs solitus. Her family consented to research but not clinical genetic testing, and the REFERENCES splicing mutation (c.958-2A4G) and missense mutation 1 Hildebrandt F, Benzing T, Katsanis N. Ciliopathies. N Engl J Med 2011; 364(16): (c.2342G4A) previously seen in her brother were identified. 1533–1543. Her clinical course included initiation of peritoneal dialysis 2 Barr M, Sternberg P. 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& 2014 Nature America, Inc. Journal of Perinatology (2014), 410 – 411