Prenatal diagnosis of 17q12 deletion syndrome: from fetal hyperechogenic kidneys to high risk for autism

Prenatal diagnosis, ultrasound findings, and pregnancy outcome of 17q12 deletion and duplication syndromes: a retrospective case series

OBJECTIVE

Analyze the ultrasound findings, single-nucleotide polymorphism array (SNP-array) results, and pregnancy outcomes of fetuses with 17q12 deletions and duplications in the second and third trimesters. Explore the prenatal ultrasound characteristics and pregnancy outcomes of these fetuses.

METHODS

Retrospective data were collected for 16 fetuses diagnosed with 17q12 deletion and seven fetuses with 17q12 duplication through SNP-array during prenatal diagnosis at a single Chinese tertiary medical center from January 2017 to December 2023. Maternal demographics, ultrasound findings of the fetuses, SNP-array results, pregnancy outcomes, and follow-up information were reviewed and analyzed. Peripheral blood from the parents was extracted to determine whether the CNVs in the fetuses were inherited or de novo.

RESULTS

The copy-number variation (CNV) sizes ranged from 1.39 to 1.94 Mb in cases of 17q12 deletion and from 1.42 to 1.91 Mb in cases of 17q12 duplication. These CNVs included 15 OMIM genes, such as HNF1B, LHX1, and ACACA. In fetuses with a 17q12 deletion, the primary manifestation was renal abnormalities (93.8%, 15/16). Of these, 13 cases (81.3%, 13/16) exhibited bilateral or unilateral hyperechogenic kidneys, and 12 cases (75%, 12/16) had multicystic hyperechogenic kidneys. Two cases (12.5%, 2/16) showed multiple organ structural abnormalities. In fetuses with a 17q12 duplication, four cases (57.1%, 4/7) revealed cardiovascular system abnormalities, including tetralogy of fallot, pulmonary artery stenosis, ventricular septal defect, and tricuspid regurgitation. Two cases (28.6%, 2/7) presented with upper gastrointestinal obstruction. Additionally, one case was particularly unique, characterized by multiple structural malformations, such as ventricular septal defect, microcephaly, cleft lip, and palate. Nine cases opted for pregnancy termination, and 14 chose to continue the pregnancy. Two cases underwent surgical treatment after birth for upper gastrointestinal obstruction, and the prognosis was good. Among the 10 cases of 17q12 deletion, six cases showed consistent prenatal ultrasound findings and postnatal clinical features. Four cases were found to have discrepancies with prenatal ultrasound findings; while the renal ultrasound phenotype appeared normal during the last follow-up, two of these cases were subsequently diagnosed with neuropsychiatric phenotypes.

CONCLUSION

Our study expanded the clinical phenotype spectrum of fetuses with 17q12 deletion and duplication, and conducted a preliminary evaluation of prenatal ultrasound findings and postnatal clinical phenotypes in follow-up cases. We further demonstrated a high correlation between fetuses with 17q12 deletion and hyperechogenic, multicystic kidneys. The primary manifestations in fetuses with 17q12 duplication are likely cardiovascular system malformations, which also exhibit a broad spectrum of phenotypic features.

Association between rare, genetic variants linked to autism and ultrasonography fetal anomalies in children with autism spectrum disorder

BACKGROUND

Recent evidence suggests that certain fetal anomalies detected upon prenatal ultrasound screenings are associated with autism spectrum disorder (ASD). In this cross-sectional study, we aimed to identify genetic variants associated with fetal ultrasound anomalies (UFAs) in children with ASD.

METHODS

The study included all children with ASD who are registered in the database of the Azrieli National Center of Autism and Neurodevelopment and for whom both prenatal ultrasound and whole exome sequencing (WES) data were available. We applied our in-house integrative bioinformatics pipeline, AutScore, to these WES data to prioritize rare, gene-disrupting variants (GDVs) probably contributing to ASD susceptibily. Univariate statistics and multivariable regression were used to assess the associations between UFAs and GDVs identified in these children.

RESULTS

The study sample comprised 126 children, of whom 43 (34.1%) had at least one UFA detected in the prenatal ultrasound scan. A total of 87 candidate ASD genetic variants were detected in 60 children, with 24 (40%) children carrying multiple variants. Children with UFAs were more likely to have loss-of-function (LoF) mutations (aOR = 2.55, 95%CI: 1.13-5.80). This association was particularly noticeable when children with structural anomalies or children with UFAs in their head and brain scans were compared to children without UFAs (any mutation: aOR = 8.28, 95%CI: 2.29-30.01; LoF: aOR = 5.72, 95%CI: 2.08-15.71 and any mutation: aOR = 6.39, 95%CI: 1.34-30.47; LoF: aOR = 4.50, 95%CI: 1.32-15.35, respectively). GDVs associated with UFAs were enriched in genes highly expressed across all tissues (aOR = 2.76, 95%CI: 1.14-6.68). There was a weak, but significant, correlation between the number of mutations and the number of abnormalities detected in the same children (r = 0.21, P = 0.016).

CONCLUSIONS

The results provide valuable insights into the potential genetic basis of prenatal organogenesis abnormalities associated with ASD and shed light on the complex interplay between genetic factors and fetal development.

Fetal hyperechoic kidneys: Diagnostic considerations and genetic testing strategies

Isolated bilateral hyperechoic kidneys (HEK) on prenatal ultrasound presents diagnostic, prognostic, and counseling challenges. Prognosis ranges from normal outcome to lethal postnatally. Presence/absence of extra-renal malformations, gestational age at presentation, amniotic fluid volume, and renal size may distinguish underlying etiologies and thereby prognosis, as prognosis is highly dependent upon underlying etiology. An underlying genetic diagnosis, clearly impactful, is determined in only 55%-60% of cases. We conducted a literature review of chromosomal (aneuploidies, copy number variants [CNVs]) single genes and other etiologies of fetal bilateral HEK, summarized how this information informs prognosis and recurrence risk, and critically assessed laboratory testing strategies. The most commonly identified etiologies are autosomal recessive and autosomal dominant polycystic kidney disease and microdeletions at 17q12 involving HNF1b. With rapid gene discovery, alongside advances in prenatal imaging and fetal phenotyping, the growing list of single gene diagnoses includes ciliopathies, overgrowth syndromes, and renal tubular dysgenesis. At present, microarray and gene panels or whole exome sequencing (WES) are first line tests employed for diagnostic evaluation. Whole genome sequencing (WGS), with the ability to detect both single nucleotide variants (SNVs) and CNVs, would be expected to provide the highest diagnostic yield.

Characterization of the prenatal renal phenotype associated with 17q12, HNF1B, microdeletions

OBJECTIVE

Recurrent deletions involving 17q12 are associated with a variety of clinical phenotypes, including congenital abnormalities of the kidney and urinary tract (CAKUT), maturity onset diabetes of the young, type 5, and neurodevelopmental disorders. Structural and/or functional renal disease is the most common phenotypic feature, although the prenatal renal phenotypes and the postnatal correlates have not been well characterized.

METHOD

We reviewed pre- and postnatal medical records of 26 cases with prenatally or postnatally identified 17q12/HNF1B microdeletions (by chromosomal microarray or targeted gene sequencing), obtained through a multicenter collaboration. We specifically evaluated 17 of these cases (65%) with reported prenatal renal ultrasound findings.

RESULTS

Heterogeneous prenatal renal phenotypes were noted, most commonly renal cysts (41%, n = 7/17) and echogenic kidneys (41%), although nonspecific dysplasia, enlarged kidneys, hydronephrosis, pelvic kidney with hydroureter, and lower urinary tract obstruction were also reported. Postnatally, most individuals developed renal cysts (73%, 11/15 live births), and there were no cases of end-stage renal disease during childhood or the follow-up period.

CONCLUSION

Our findings demonstrate that copy number variant analysis to assess for 17q12 microdeletion should be considered for a variety of prenatally detected renal anomalies. It is important to distinguish 17q12 microdeletion from other etiologies of CAKUT as the prognosis for renal function and presence of associated findings are distinct and may influence pregnancy and postnatal management.

Prenatal diagnosis and perinatal findings of 17q12 microdeletion encompassing HNF1B in a fetus with bilateral hyperechogenic kidneys on fetal ultrasound and mild renal abnormality after birth, and a review of the literature of prenatal diagnosis of 17q12 microdeletion

OBJECTIVE

We present prenatal diagnosis and perinatal findings of 17q12 microdeletion encompassing HNF1B in a fetus with bilateral hyperechogenic kidneys on fetal ultrasound and mild renal abnormality after birth, and a review of the literature.

CASE REPORT

A 36-year-old, primigravid woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes showed a de novo 1.38-Mb 17q12 microdeletion encompassing LHX1 and HNF1B. The parents did not have such a microdeletion. Prenatal ultrasound showed bilateral hyperechogenic kidneys with normal corticomedullary (CM) differentiation. The parents elected to continue the pregnancy, and a grossly normal 3180-g male baby was delivered at 39 weeks of gestation. aCGH analysis on the cord blood DNA revealed arr [GRCh37 (hg19)] 17q12 (34,856,055-36,248,918) × 1.0 with a 1.393-Mb microdeletion encompassing the genes of MYO19, PIGW, GGNBP2, DHRS11, MRM1, LHX1, AATF, ACACA, TADA2A, DUSP14, SYNRG, DDX52 and HNF1B. When follow-up at age 2 years and 4 months, the renal ultrasound revealed bilateral increased renal echogenicity with normal CM differentiation and small left renal cysts. The blood test revealed BUN = 28 mg/dL (normal: 5-18 mg/dL) and creatinine = 0.5 mg/dL (normal: 0.2-0.4 mg/dL).

CONCLUSION

17q12 microdeletion encompassing LHX1 and HNF1B at prenatal diagnosis may present variable clinical spectrum with bilateral hyperechogenic kidneys on fetal ultrasound and mild renal abnormality after birth. Prenatal diagnosis of fetal hyperechogenic kidneys should raise a suspicion of 17q12 microdeletion syndrome.

Fetal hyperechoic kidney cohort study and a meta-analysis

Objective: To investigate the positive rate of chromosomal and monogenic etiologies and pregnancy outcomes in fetuses with hyperechoic kidney, and to provide more information for genetic counseling and prognosis evaluation. Methods: We performed a retrospective analysis of 25 cases of hyperechoic kidney diagnosed prenatal in the Second Affiliated Hospital of Harbin Medical University and Harbin Red Cross Central Hospital (January 2017-December 2022). Furthermore, we conducted a meta-analysis of a series of hyperechoic kidneys (HEK) in the literature to assess the incidence of chromosomal and monogenic etiologies, mortality, and pooled odds ratio (OR) estimates of the association between the incidence of these outcomes and other associated ultrasound abnormalities. Results: 25 fetuses of HEK were enrolled in the cohort study, including 14 with isolated hyperechoic kidney (IHK) and 11 with non-isolated hyperechoic kidney (NIHK). Chromosomal aneuploidies were detected in 4 of 20 patients (20%). The detection rate of pathogenic or suspected pathogenic copy number variations (CNVs) was 29% (4/14) for IHK and 37% (4/11) for NIHK. Whole exome sequencing (WES) was performed in 5 fetuses, and pathogenic genes were detected in all of them. The rate of termination of pregnancy was 56% in HEK. 21 studies including 1,178 fetuses were included in the meta-analysis. No case of abnormal chromosome karyotype or (intrauterine death)IUD was reported in fetuses with IHK. In contrast, the positive rate of karyotype in NIHK was 22% and that in HEK was 20%, with the ORs of 0.28 (95% CI 0.16-0.51) and 0.25, (95% CI 0.14-0.44), respectively. The positive rate of (chromosome microarray analysis) CMA in IHK was 59% and that in NIHK was 32%, with the ORs of 1.46 (95% CI 1.33-1.62) and 0.48 (95% CI, 0.28-0.85), respectively. The positive rate of monogenic etiologies in IHK was 31%, with the OR of 0.80 (95% CI 0.25-2.63). In IHK, the termination rate was 21% and neonatal mortality was 13%, with the ORs of 0.26 (95% CI, 0.17-0.40), 1.72 (95% CI, 1.59-1.86), and that in NIHK was 63%, 0.15 (95% CI, 0.10-0.24); 11%, 0.12 (95% CI, 0.06-0.26), respectively. The intrauterine mortality in NIHK group was 2%, with the OR of 0.02 (95% CI, 0.01-0.05). HNF1B variant has the highest incidence (26%) in IHK. Conclusion: The positive rate of karyotype was 20% in HEK and 22% in NIHK. The positive rate of CMA was 32% in NIHK and 59% in IHK. The positive rate of IHK monogenic etiologies was 31%. HNF1B gene variation is the most common cause of IHK. The overall fetal mortality rate of NIHK is significantly higher than that of IHK. The amount of amniotic fluid, kidney size and the degree of corticomedullary differentiation have a great impact on the prognosis, these indicators should be taken into consideration to guide clinical consultation and decision-making.

Review of neurodevelopmental disorders in patients with HNF1B gene variations

This review investigates the association between neurodevelopmental disorders (NDD) and variations of the gene HNF1B. Heterozygous intragenetic mutations or heterozygous gene deletions (17q12 microdeletion syndrome) of HNF1B are the cause of a multi-system developmental disorder, termed renal cysts and diabetes syndrome (RCAD). Several studies suggest that in general, patients with genetic variation of HNF1B have an elevated risk for additional neurodevelopmental disorders, especially autism spectrum disorder (ASD) but a comprehensive assessment is yet missing. This review provides an overview including all available studies of patients with HNF1B mutation or deletion with comorbid NDD with respect to the prevalence of NDDs and in how they differ between patients with an intragenic mutation or 17q12 microdeletion. A total of 31 studies was identified, comprising 695 patients with variations in HNF1B, (17q12 microdeletion N = 416, mutation N = 279). Main results include that NDDs are present in both groups (17q12 microdeletion 25.2% vs. mutation 6.8%, respectively) but that patients with 17q12 microdeletions presented more frequently with any NDDs and especially with learning difficulties compared to patients with a mutation of HNF1B. The observed prevalence of NDDs in patients with HNF1B variations seems to be higher than in the general population, but the validity of the estimated prevalence must be deemed insufficient. This review shows that systematical research of NDDs in patients with HNF1B mutations or deletions is lacking. Further studies regarding neuropsychological characteristics of both groups are needed. NDDs might be a concomitant of HFN1B-related disease and should be considered in clinical routine and scientific reports.

Phenotypic Variability of 17q12 Microdeletion Syndrome – Three Cases and Review of Literature

Chromosome 17q12 microdeletion syndrome is a contiguous gene deletion syndrome caused by an 1–2 Mb loss, characterized by multicystic dysplastic kidneys or other urinary system anomalies starting in utero, including autism or maturity-onset diabetes of the young in its postnatal phenotype. Here, we report on three cases (two prenatal and one postnatal) with distinct and novel clinical presentations as compared with a large number of reviewed patients, thus emphasizing the phenotypic variability of this syndrome and the consequent difficulties in genetic counselling. Prenatal hyperechogenic multicystic kidneys, as well as other urinary tract anomalies, should be considered a marker, therefore indicating the necessity of comprehensive genetic testing, and autism should also be acknowledged as a possible clinical presentation, postnatally.

Genetic diagnosis of common fetal renal abnormalities detected on prenatal ultrasound

OBJECTIVES

This retrospective study aimed to investigate the correlations between phenotypes of fetal renal abnormalities on prenatal ultrasound and genetic aetiologies detected using chromosomal microarray analysis (CMA) and whole-exome sequencing (WES).

METHODS

Fetuses with renal abnormalities were subjected to CMA and were further analysed by WES when CMA-negative. The detection rates for chromosomal abnormalities and monogenic variants among different types of isolated renal abnormalities and those with extrarenal abnormalities (non-isolated cases) were determined and compared.

RESULTS

CMA detected chromosomal abnormalities in 78 of 577 fetuses (13.52%). WES detected monogenic variants in 31 of 160 fetuses (19.38%) that had non-diagnostic CMA results. In cases of isolated hyperechogenic kidney, polycystic kidney disease, and multicystic dysplastic kidney, the detection rates of copy number variants (CNVs) by CMA and monogenic variants by WES were not significantly different (P > 0.05). However, monogenic variants were more frequently detected than CNVs when kidney abnormalities were accompanied by reduced amniotic fluid (P < 0.05). Other renal abnormalities identified on prenatal ultrasound had different detection rates.

CONCLUSIONS

Our findings contribute to the overall knowledge of genetic variants associated with prenatally identified renal anomalies and may aid in decision making regarding prenatal genetic testing options for affected pregnancies. This article is protected by copyright. All rights reserved.

Association of prenatal renal ultrasound abnormalities with pathogenic copy number variants in a large Chinese cohort

OBJECTIVES

To assess the clinical utility of prenatal chromosomal microarray analysis (CMA) in fetuses with abnormal renal sonographic findings, and to evaluate the association of pathogenic or likely pathogenic copy number variants (P/LP CNVs) with different types of renal abnormality.

METHODS

This was a retrospective study of fetuses at 14-36 weeks screened routinely for renal and other structural abnormalities at the Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region. We retrieved and analyzed data from fetuses with abnormal renal sonographic findings, examined between January 2013 and November 2019, which underwent CMA analysis using tissue obtained from chorionic villus sampling (CVS), amniocentesis or cordocentesis. We evaluated the CMA findings according to type of renal ultrasound anomaly and according to whether renal anomalies were isolated or non-isolated.

RESULTS

Ten types of renal anomaly were reported on prenatal ultrasound screening, at a mean ± SD gestational age of 24.9 ± 4.8 weeks. The anomalies were diagnosed relatively late in this series, as 64% of cases with an isolated renal anomaly underwent cordocentesis rather than CVS. Fetal pyelectasis was the most common renal ultrasound finding, affecting around one-third (34.32%, 301/877) of fetuses with a renal anomaly, but only 3.65% (n = 11) of these harbored a P/LP CNV (comprising: isolated cases, 2.37% (4/169); non-isolated cases, 5.30% (7/132)). Hyperechogenic kidney was found in 5.47% (n = 48) of fetuses with a renal anomaly, of which 39.58% (n = 19) had a P/LP CNV finding (comprising: isolated cases, 44.44% (16/36); non-isolated cases, 25.00% (3/12)), the highest diagnostic yield among the different types of renal anomaly. Renal agenesis, which accounted for 9.92% (n = 87) of all abnormal renal cases, had a CMA diagnostic yield of 12.64% (n = 11) (comprising: isolated cases, 11.54% (9/78); non-isolated cases, 22.22% (2/9); unilateral cases, 11.39% (9/79); bilateral cases, 25.00% (2/8)), while multicystic dysplastic kidney (n = 110), renal cyst (n = 34), renal dysplasia (n = 27), crossed fused renal ectopia (n = 31), hydronephrosis (n = 98), renal duplication (n = 42) and ectopic kidney (n = 99) had overall diagnostic rates of 11.82%, 11.76%, 7.41%, 6.45%, 6.12%, 4.76% and 3.03%, respectively. Compared with the combined group of CMA-negative fetuses with any other type of renal anomaly, the rate of infant being alive and well at birth was significantly higher in CMA-negative fetuses with isolated fetal pyelectasis or ectopic kidney, whereas the rate was significantly lower in fetuses with isolated renal agenesis, multicystic dysplastic kidney or severe hydronephrosis. The most common pathogenic CNV was 17q12 deletion, which accounted for 30.14% (22/73) of all positive CMA findings, with a rate of 2.51% (22/877) among fetuses with an abnormal renal finding. Fetuses with 17q12 deletion exhibited a wide range of renal phenotypes. Other P/LP CNVs in the recurrent region that were associated with prenatal renal ultrasound abnormalities included 22q11.2, Xp21.1, Xp22.3, 2q13, 16p11.2 and 1q21, which, collectively, accounted for 2.17% (19/877) of the fetuses with prenatal renal anomalies.

CONCLUSIONS

In this retrospective review of CMA findings in a large cohort of fetuses with different types of renal ultrasound abnormality, the P/LP CNV detection rate varied significantly (3.03-39.58%) among the different types of kidney anomaly. Our data may help in the decision regarding whether to perform prenatal genetic testing in fetuses with renal ultrasound findings. Specifically, prenatal CMA testing should be performed in cases of hyperechogenic kidney, regardless of whether or not the anomaly is isolated, while it should be performed postnatally rather than prenatally in cases of fetal pyelectasis. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

OUP accepted manuscript

Multiple pieces of evidence support the prenatal predisposition of autism spectrum disorder (ASD). Nevertheless, robust data about abnormalities in foetuses later developing into children diagnosed with ASD are lacking. Prenatal ultrasound is an excellent tool to study abnormal foetal development as it is frequently used to monitor foetal growth and identify foetal anomalies throughout pregnancy. We conducted a retrospective case-sibling-control study of children diagnosed with ASD (cases); their own typically developing, closest-in-age siblings (TDS); and typically developing children from the general population (TDP), matched by year of birth, sex and ethnicity to investigate the association between ultrasonography foetal anomalies and ASD. The case group was drawn from all children diagnosed with ASD enrolled at the National Autism Research Center of Israel. Foetal ultrasound data from the foetal anatomy survey were obtained from prenatal ultrasound clinics of Clalit Health Services in southern Israel. The study comprised 659 children: 229 ASD, 201 TDS and 229 TDP. Ultrasonography foetal anomalies were found in 29.3% of ASD cases versus only 15.9% and 9.6% in the TDS and TDP groups [adjusted odds ratio (aOR) = 2.23, 95% confidence interval (CI) = 1.32-3.78, and aOR = 3.50, 95%CI = 2.07-5.91, respectively]. Multiple co-occurring ultrasonography foetal anomalies were significantly more prevalent among ASD cases. Ultrasonography foetal anomalies in the urinary system, heart, and head and brain were the most significantly associated with ASD diagnosis (aORUrinary = 2.08, 95%CI = 0.96-4.50 and aORUrinary = 2.90, 95%CI = 1.41-5.95; aORHeart = 3.72, 95%CI = 1.50-9.24 and aORHeart = 8.67, 95%CI = 2.62-28.63; and aORHead&Brain = 1.96, 95%CI = 0.72-5.30 and aORHead&Brain = 4.67, 95%CI = 1.34-16.24; versus TDS and TDP, respectively). ASD females had significantly more ultrasonography foetal anomalies than ASD males (43.1% versus 25.3%, P = 0.013) and a higher prevalence of multiple co-occurring ultrasonography foetal anomalies (15.7% versus 4.5%, P = 0.011). No sex differences were seen among TDS and TDP controls. ASD foetuses were characterized by a narrower head and a relatively wider ocular-distance versus TDP foetuses (ORBPD = 0.81, 95%CI = 0.70-0.94, and aOROcular distance = 1.29, 95%CI = 1.06-1.57). Ultrasonography foetal anomalies were associated with more severe ASD symptoms. Our findings shed important light on the multiorgan foetal anomalies associated with ASD.

Prenatal ultrasound phenotypic and genetic etiology of the 17q12 microduplication syndrome

BACKGROUND

Several studies have reported on the clinical phenotype of the 17q12 microduplication syndrome, a rare autosomal dominant genetic disorder, in children and adults, but few have reported on its prenatal diagnosis. This study analyzed the prenatal ultrasound phenotypes of the 17q12 microduplication syndrome to improve the understanding, diagnosis, and monitoring of this disease in fetuses.

METHODS

A retrospective analysis of 8,200 pregnant women who had received an invasive antenatal diagnosis at tertiary referral hospitals between January 2016 and August 2021 was performed. Amniotic fluid or cord blood was sampled from the pregnant women for karyotyping and chromosome microarray analysis (CMA).

RESULTS

The CMA revealed microduplication in the 17q12 region of the genome in five fetuses, involving fragments of about 1.5-1.9 Mb. Five fetuses with the 17q12 microduplication syndrome had different prenatal ultrasound phenotypes, including duodenal obstruction (two fetuses); mild ventriculomegaly, dysplasia of the septum pellucidum, agenesis of the corpus callosum (one fetus); and a strong echo in the left ventricle only (one fetus). The ultrasound phenotype of one fetus was normal. Among the five fetuses with the 17q12 microduplication syndrome, the parents of three refused CNV segregation analysis, while CNV segregation analysis was performed for the remaining two fetuses to confirm whether the disorder was inherited maternally or paternally, with normal phenotypes. After genetic counseling, the parents of those two fetuses chose to terminate the pregnancy, while the parents of the three unverified fetuses continued the pregnancy, with normal follow-up after birth.

CONCLUSION

Although prenatal ultrasound phenotypes in fetuses with the 17q12 microduplication syndrome are highly variable, our study has highlighted the distinct association between duodenal obstruction and the 17q12 microduplication syndrome. Understanding the relationship between the pathogenesis of the 17q12 microduplication in prenatal ultrasound phenotypes and its long-term prognosis will contribute to better genetic counseling concerning the 17q12 microduplication syndrome, which is still a challenge.

Improving renal phenotype and evolving extra-renal features of 17q12 deletion encompassing the HNF1B gene

BACKGROUND

HNF1B deletion/intragenic mutations are the most commonly identified genetic cause of congenital anomalies of the kidney and urinary tract (CAKUT) suggested by fetal ultrasound findings such as: parenchymal hyperechogenicity, overt cystic changes or gross morphological urinary system (UT) abnormalities. The postnatal evolution of these 17q12 deletions encompassing the HNF1B gene-associated findings has not been assessed in depth.

METHODS

In this observational study, we present postnatal follow-up findings in 5 of 6 cases (one pregnancy was terminated on parental request) of fetal-onset cystic/hyperechogenic kidneys eventually diagnosed with 17q12 microdeletion encompassing the HNF1B gene between 2009 and 2017.

RESULTS

Complete normalization of kidney parenchymal abnormalities and of depressed neonatal renal function was observed in 4/5 and 5/5 patients within 2-4.9 years and 1.5-8 months, respectively. All 5 patients had preserved normal renal function at 3-11 years of follow-up. The evolving later-onset renal features included: hypomagnesemia, hyperuricemia, urinary tract infection (UTI), and bilateral grade 3-4 vesicoureteral reflux and bladder diverticula in 3, 3, 2, and 1 patient, respectively. HNF1B gene deletion-associated extra-renal manifestations with delayed presentation were global developmental delay/autistic spectrum disorder (ASD), rolandic-type seizures, overweight, and borderline fasting hyperglycemia observed in 1-2 patients each. Family history was positive for small-size or asymptomatic cystic kidneys with normal function, diabetes mellitus, seizures, and mental/psychiatric problems in 3/6 cases.

CONCLUSIONS

Fetal-onset HNF1B deletion-associated kidneys' parenchymal abnormalities confirmed postnatally with initially depressed renal function might undergo complete resolution within several years and few months, respectively. However, later-onset urinary tract, metabolic, and neurodevelopmental features of this mutation might appear over years. Therefore, genetic molecular evaluation/diagnosis and continuous follow-up for evolving features are mandatory in affected children.

Prenatal features of 17q12 microdeletion and microduplication syndromes: A retrospective case series

OBJECTIVE

To present the experience on prenatal features of 17q12 microdeletion and microduplication syndromes.

MATERIALS AND METHODS

Prenatal chromosomal microarray analysis (CMA) were conducted between January 2015 and December 2018 at a single Chinese tertiary medical centre. Information of cases identified with 17q12 microdeletion or microduplication syndromes were retrospectively collected. Foetal ultrasonographic findings were reviewed, and other information about the gestation week at diagnosis, inheritance and pregnancy outcomes were also included.

RESULTS

Ten pregnancies with 17q12 microdeletion and 4 with 17q12 microduplication were identified. The copy number variation (CNV) sizes were 1.39-1.94 Mb in the deleted cases and 1.42-1.48 Mb in the duplicated cases, respectively. All the duplicated and deleted regions included HNF1B and LHX1 genes. Most individuals with 17q12 deletion presented kidney anomalies (9/10), with renal hyperechogenicity being the most common finding (7/10). Fetuses with 17q12 duplication presented a wide phenotypic spectrum, including "double bubble" sign, structural anomalies of the heart and growth anomalies.

CONCLUSIONS

Our experience further demonstrated the high correlation between 17q12 microdeletion and renal anomalies especially hyperechogenic kidneys. Structural anomalies of the heart were newly identified phenotypes of 17q12 duplication during prenatal period. Besides, growth anomalies and duodenal atresia might be associated with the duplication.

Prenatal diagnosis of HNF1B-associated renal cysts: Is there a need to differentiate intragenic variants from 17q12 microdeletion syndrome?

OBJECTIVE

17q12 microdeletions containing HNF1B and intragenic variants within this gene are associated with variable developmental, endocrine, and renal anomalies, often already noted prenatally as hyperechogenic/cystic kidneys. Here, we describe prenatal and postnatal phenotypes of seven individuals with HNF1B aberrations and compare their clinical and genetic data to those of previous studies.

METHODS

Prenatal sequencing and postnatal chromosomal microarray analysis were performed in seven individuals with renal and/or neurodevelopmental phenotypes. We evaluated HNF1B-related clinical features from 82 studies and reclassified 192 reported intragenic HNF1B variants.

RESULTS

In a prenatal case, we identified a novel in-frame deletion p.(Gly239del) within the HNF1B DNA-binding domain, a mutational hot spot as demonstrated by spatial clustering analysis and high computational prediction scores. The six postnatally diagnosed individuals harbored 17q12 microdeletions. Literature screening revealed variable reporting of HNF1B-associated clinical traits. Overall, both mutation groups showed a high phenotypic heterogeneity. The reclassification of all previously reported intragenic HNF1B variants provided an up-to-date overview of the mutational spectrum.

CONCLUSIONS

We highlight the value of prenatal HNF1B screening in renal developmental diseases. Standardized clinical reporting and systematic classification of HNF1B variants are necessary for a more accurate risk quantification of prenatal and postnatal clinical features, improving genetic counseling and prenatal decision making.

School level of children carrying a HNF1B variant or a deletion

The prevalence of neurological involvement in patients with a deletion of or a variant in the HNF1B gene remains discussed. The aim of this study was to investigate the neuropsychological outcomes in a large cohort of children carrying either a HNF1B whole-gene deletion or a disease-associated variant, revealed by the presence of kidney anomalies. The neuropsychological development-based on school level-of 223 children included in this prospective cohort was studied. Data from 180 children were available for analysis. Patients mean age was 9.6 years, with 39.9% of girls. Among these patients, 119 carried a HNF1B deletion and 61 a disease-associated variant. In the school-aged population, 12.7 and 3.6% of patients carrying a HNF1B deletion and a disease-associated variant had special educational needs, respectively. Therefore, the presence of a HNF1B deletion increases the risk to present with a neuropsychiatric involvement when compared with the general population. On the other hand, almost 90% of patients carrying a HNF1B disease-associated variant or deletion have a normal schooling in a general educational environment. Even if these findings do not predict the risk of neuropsychiatric disease at adulthood, most patients diagnosed secondary to kidney anomalies do not show a neurological outcome severe enough to impede standard schooling at elementary school. These results should be taken into account in prenatal counseling.

Chromosomal microarray analysis in fetuses with congenital anomalies of the kidney and urinary tract: A prospective cohort study and meta-analysis

OBJECTIVE

To evaluate the usefulness and incremental diagnostic yield of chromosomal microarray analysis (CMA) compared with standard karyotyping in fetuses with congenital anomalies of the kidney and urinary tract (CAKUT).

METHODS

A prospective cohort study and systematic review of the literature were conducted. In the prospective cohort study, 123 fetuses with CAKUT, as detected by prenatal ultrasound at our center, were enrolled and evaluated using karyotyping and CMA. In the meta-analysis, articles in PubMed and ISI Web of Knowledge databases describing copy number variations (CNVs) in prenatal cases of CAKUT were included.

RESULTS

Among the 123 fetuses in our prospective cohort study, 13 fetuses were detected with chromosomal abnormalities or submicroscopic chromosomal abnormalities by both karyotyping and CMA. In the remaining 110 fetuses, four pathogenic CNVs in four fetuses were only detected by CMA, indicating an excess diagnostic yield of 3.6%. Six publications and our own study met the inclusion criteria for the meta-analysis. In total, 615 fetuses with CAKUT were included. The pooled data from all of the reviewed studies indicate that the incremental yield of CMA over karyotyping was 3.8%.

CONCLUSION

The use of CMA provides a 3.8% incremental yield of detecting pathogenic CNVs in fetuses with CAKUT and normal karyotype.

An alternative to array-based diagnostics: a prospectively recruited cohort, comparing arrayCGH to next-generation sequencing to evaluate foetal structural abnormalities

Molecular diagnostic investigations, following the identification of foetal abnormalities, are routinely performed using array comparative genomic hybridisation (aCGH). Despite the utility of this technique, contemporary approaches for the detection of copy number variation are typically based on next-generation sequencing (NGS). We sought to compare an in-house NGS-based workflow (CNVseq) with aCGH, for invasively obtained foetal samples from pregnancies complicated by foetal structural abnormality. DNA from 40 foetuses was screened using both 8 × 60 K aCGH oligoarrays and low-coverage whole genome sequencing. Sequencer-compatible libraries were combined in a ten-sample multiplex and sequenced using an Illumina HiSeq2500. The mean resolution of CNVseq was 29 kb, compared to 60 kb for aCGH analyses. Four clinically significant, concordant, copy number imbalances were detected using both techniques, however, genomic breakpoints were more precisely defined by CNVseq. This data indicates CNVseq is a robust and sensitive alternative to aCGH, for the prenatal investigation of foetuses with structural abnormalities. Impact statement What is already known about this subject? Copy number variant analysis using next-generation sequencing has been successfully applied to investigations of tumour specimens and patients with developmental delays. The application of our approach, to a prospective prenatal diagnosis cohort, has not hitherto been assessed. What do the results of this study add? Next-generation sequencing has a comparable turnaround time and assay sensitivity to copy number variant analysis performed using array CGH. We demonstrate that having established a next-generation sequencing facility, high-throughput CNVseq sample processing and analysis can be undertaken within the framework of a regional diagnostic service. What are the implications of these findings for clinical practice and/or further research? Array CGH is a legacy technology which is likely to be superseded by low-coverage whole genome sequencing, for the detection of copy number variants, in the prenatal diagnosis of structural abnormalities.