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

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.

HNF1B Transcription Factor: Key Regulator in Renal Physiology and Pathogenesis

The HNF1B gene, located on chromosome 17q12, encodes a transcription factor essential for the development of several organs. It regulates the expression of multiple genes in renal, pancreatic, hepatic, neurological, and genitourinary tissues during prenatal and postnatal development, influencing processes such as nephrogenesis, cellular polarity, tight junction formation, cilia development, ion transport in the renal tubule, and renal metabolism. Mutations that alter the function of Hnf1b deregulate those processes, leading to various pathologies characterized by both renal and extrarenal manifestations. The main renal diseases that develop are polycystic kidney disease, hypoplastic or dysplastic kidneys, structural abnormalities, Congenital Anomalies of the Kidney and Urinary Tract (CAKUT), and electrolyte imbalances such as hyperuricemia and hypomagnesemia. Extrarenal manifestations include Maturity-Onset Diabetes of the Young (MODY), hypertransaminasemia, genital and urinary tract malformations, Autism Spectrum Disorder (ASD), and other neurodevelopmental disorders. Patients with HNF1B alterations typically carry either punctual mutations or a monoallelic microdeletion in the 17q12 region. Future research on the molecular mechanisms and genotype-phenotype correlations in HNF1B-related conditions will enhance our understanding, leading to improved clinical management, genetic counseling, monitoring, and patient care.

A Korean Family Presenting with Renal Cysts and Maturity-Onset Diabetes of the Young Caused by a Novel In-Frame Deletion of HNF1B

Maturity-onset diabetes of the young (MODY; OMIM # 606391) comprises a cluster of inherited disorders within non-autoimmune diabetes mellitus (DM), typically emerging during adolescence or young adulthood. We report a novel in-frame deletion of HNF1B in a family with renal cysts and MODY, furthering our understanding of HNF1B-related phenotypes. We conducted sequential genetic testing to investigate the glucose intolerance, renal cysts, hepatic cysts, and agenesis of the dorsal pancreas observed in the proband. A comprehensive clinical exome sequencing approach using a Celemics G-Mendeliome Clinical Exome Sequencing Panel was employed. Considering the clinical manifestations observed in the proband, gene panel sequencing identified a heterozygous HNF1B variant, c.36_38delCCT/p.(Leu13del) (reference transcript ID: NM_000458.4), as the most likely cause of MODY in the proband. The patient's clinical presentation was consistent with MODY caused by the HNF1B variant, showing signs of glucose intolerance, renal cysts, hepatic cysts, and agenesis of the dorsal pancreas. Sanger sequencing confirmed the same HNF1B variant and established the paternally inherited autosomal dominant status of the heterozygous variant in the patient, as well as in his father and sister. The presence of early-onset diabetes, renal cysts, a family history of the condition, and nephropathy appearing before or after the diagnosis of diabetes mellitus (DM) suggests a diagnosis of HNF1B-MODY5. Early diagnosis is crucial for preventing complications of DM, enabling family screening, providing pre-conceptional genetic counseling, and monitoring kidney function decline.

Renal and Extrarenal Phenotypes in Patients With HNF1B Variants and Chromosome 17q12 Microdeletions

Introduction

Hepatocyte nuclear factor 1-beta (HNF1B) gene variants or the chromosome 17q12 deletion (17q12del) represent the most common monogenic cause of developmental kidney disease. Although neurodevelopmental disorders have been associated with the 17q12del, specific genotype-phenotype associations with respect to kidney function evolution have not yet been fully defined. Here, we aimed to determine whether 17q12del or specific HNF1B variants were associated with kidney survival in a large patient population with HNF1B disease.

Methods

This was a retrospective observational study involving 521 patients with HNF1B disease from 14 countries using the European Reference Network for rare kidney diseases with detailed information on the HNF1B genotype (HNF1B variants or the 17q12del). Median follow-up time was 11 years with 6 visits per patient. The primary end point was progression to chronic kidney disease (CKD) stage 3 (estimated glomerular filtration rate [eGFR] < 60 ml/min per 1.73 m2). Secondary end points were the development of hypomagnesemia or extrarenal disorders, including hyperuricemia and hyperglycemia.

Results

Progression toward CKD stage 3 was significantly delayed in patients with the 17q12del compared to patients with HNF1B variants (hazard ratio [HR]: 0.29, 95% confidence interval [CI]: 0.19-0.44, P < 0.001). Progression toward CKD stage 3 was also significantly delayed when HNF1B variants involved the HNF1B Pit-1, Oct-1, and Unc-86 homeodomain (POUh) DNA-binding and transactivation domains rather than the POU-specific domain (POUs) DNA-binding domain (HR: 0.15 [95% CI: 0.06-0.37), P < 0.001 and HR: 0.25 (95% CI: 0.11-0.57), P = 0.001, respectively). Finally, the 17q12del was positively associated with hypomagnesemia and negatively associated with hyperuricemia, but not with hyperglycemia.

Conclusion

Patients with the 17q12del display a significantly better kidney survival than patients with other HNF1B variants; and for the latter, variants in the POUs DNA-binding domain lead to the poorest kidney survival. These are clinically relevant HNF1B kidney genotype-phenotype correlations that inform genetic counseling.

A Case of 17q12 Microdeletion Syndrome in a MODY5 Type Diabetes with HNF-1β Gene Mutation Accompanied

Maturity Onset Diabetes of the Young (MODY) is an autosomal dominant inherited disorder prevalent among adolescents. Typically, it manifests with hyperglycemia before the age of 25. MODY5 is attributed to a mutation in the Hepatocyte Nuclear Factor-1β (HNF-1β) gene. A complete absence of HNF-1β is observed in 50% of those with MODY5. The 17q12 microdeletion syndrome closely linked with MODY5. Its incidence in the general population is around 1 in 14,500 and is linked with facial deformities, diabetes, polycystic kidneys, pancreatic hypertrophy, liver anomalies, and neuropsychological impairments. The most primary clinical signs are predominantly associated with the HNF-1β gene deletion. We chronicle the case of a male of 19 years of age diagnosed with diabetes, who, alongside persistent liver damage and polycystic kidneys, was referred from a community hospital to the Xuzhou Central Hospital. His clinical presentation included diabetes, liver dysfunction, polycystic kidneys, lipid irregularities, insulin resistance, and fatty atrophy. Subsequent genetic screening unveiled a 17q12 chromosomal deletion and an absence of the Hepatocyte Nuclear Factor-1β (HNF-1β) gene. Hence, for adolescent patients lacking a familial diabetes history but exhibiting symptoms like polycystic kidneys, liver damage, lipid irregularities, and fatty atrophy, a thorough assessment for the 17q12 microdeletion syndrome becomes imperative.

Diagnostic Yield and Benefits of Whole Exome Sequencing in CAKUT Patients Diagnosed in the First Thousand Days of Life

Introduction

Congenital anomalies of the kidney and urinary tract (CAKUT) are the predominant cause of chronic kidney disease (CKD) and the need for kidney replacement therapy (KRT) in children. Although more than 60 genes are known to cause CAKUT if mutated, genetic etiology is detected, on average, in only 16% of unselected CAKUT cases, making genetic testing unproductive.

Methods

Whole exome sequencing (WES) was performed in 100 patients with CAKUT diagnosed in the first 1000 days of life with CKD stages 1 to 5D/T. Variants in 58 established CAKUT-associated genes were extracted, classified according to the American College of Medical Genetics and Genomics guidelines, and their translational value was assessed.

Results

In 25% of these mostly sporadic patients with CAKUT, a rare likely pathogenic or pathogenic variant was identified in 1 or 2 of 15 CAKUT-associated genes, including GATA3, HNF1B, LIFR, PAX2, SALL1, and TBC1D1. Of the 27 variants detected, 52% were loss-of-function and 18.5% de novo variants. The diagnostic yield was significantly higher in patients requiring KRT before 3 years of age (43%, odds ratio 2.95) and in patients with extrarenal features (41%, odds ratio 3.5) compared with patients lacking these criteria. Considering that all affected genes were previously associated with extrarenal complications, including treatable conditions, such as diabetes, hyperuricemia, hypomagnesemia, and hypoparathyroidism, the genetic diagnosis allowed preventive measures and/or early treatment in 25% of patients.

Conclusion

WES offers significant advantages for the diagnosis and management of patients with CAKUT diagnosed before 3 years of age, especially in patients who require KRT or have extrarenal anomalies.

Identification of appropriate biochemical parameters and cut points to detect Maturity Onset Diabetes of Young (MODY) in Asian Indians in a clinic setting

Maturity Onset Diabetes of the Young (MODY) is a monogenic form of diabetes which is detected by genetic testing. We looked at clinical and biochemcial variables that could help detect possible MODY among Asian Indians with youth-onset diabetes. From the diabetes electronic medical records of a diabetes care centre in Chennai in southern India, demographic, anthropometric, and biochemical details of 34 genetically confirmed MODY participants were extracted. They were compared with patients with type 1 diabetes (T1D) (n = 1011) and type 2 diabetes (T2D) (n = 1605), diagnosed below 30 years of age. Clinical and biochemical variables including body mass index (BMI), glycated hemoglobin, HDL cholesterol, and C-peptide (fasting and stimulated) were analyzed to determine whether cut points could be derived to identify individuals who could be sent for genetic testing to diagnose or rule out MODY in this ethnic group. The age at diagnosis was higher for T2D (26.5 ± 4.0 years) compared to T1D (18.2 ± 6.1 years) and MODY (17.8 ± 6.0 years). Individuals with MODY had BMI, glycated hemoglobin, total cholesterol, triglycerides, HDL cholesterol, and C-peptide levels which were intermediate between T1D and T2D. The identified probable parameters and their cut points to identify cases for MODY genetic screening were BMI 21.2-22.7 kg/m2, glycated hemoglobin 7.2-10%, HDL cholesterol 43-45 mg/dl, fasting C -peptide, 1.2-2.1 ng/ml and stimulated C-peptide, 2.1-4.5 ng/ml. Asian Indians with MODY have clinical features that are intermediate between T1D and T2D and selected biochemical parameters, especially stimulated C peptide cut points were the most useful to diagnose MODY.

Pregnancy outcome with maternal HNF1B gene mutations and 17q12 deletions

There is an increasing body of literature regarding monogenic diabetes, particularly the more common forms of glucokinase and HNF1-alpha mutations (MODY2 and MODY3). There is relatively little published literature regarding rarer mutations. HNF1-beta mutations and 17q12 deletions may be associated with a broad range of organ dysfunction, renal disease and diabetes in particular resulting in high-risk pregnancies. This manuscript describes pregnancy outcomes in a woman with an HNF1-beta mutation and 2 women with an HNF1B/17q12 deletion and reviews the previously published literature. It highlights the significant rate of adverse maternal and fetal outcomes, and the maternal features suggestive of the diagnosis which should be considered in preconception counselling.

Prevalence, clinical features and complications of common forms of Maturity Onset Diabetes of the Young (MODY) seen at a tertiary diabetes centre in south India

BACKGROUND

Maturity Onset Diabetes of the Young (MODY) is a form of monogenic diabetes caused by mutations in single genes, affecting adolescents or young adults. MODY is frequently misdiagnosed as type 1 diabetes (T1). Though several studies from India have reported on the genetic aspects of MODY, the clinical profile, complications and treatments given have not been reported so far, nor compared with T1D and type 2 diabetes (T2D).

AIM

To determine the prevalence, clinical features, and complications of common forms of genetically proven MODY seen at a tertiary diabetes centre in South India and compare them with matched individuals with T1D and T2D.

METHODS

Five hundred and thirty individuals identified as 'possible MODY' based on clinical criteria, underwent genetic testing for MODY. Diagnosis of MODY was confirmed based on pathogenic or likely pathogenic variants found using Genome Aggregation Database (gnomAD) and American College of Medical Genetics (ACMG) criteria. The clinical profile of MODY was compared with individuals with type 1 (T1D) and type 2 (T2D) diabetes, matched for duration of diabetes. Retinopathy was diagnosed by retinal photography; nephropathy by urinary albumin excretion > 30 µg/mg of creatinine and neuropathy by vibration perception threshold > 20 v on biothesiometry.

RESULTS

Fifty-eight patients were confirmed to have MODY (10.9%). HNF1A-MODY (n = 25) was the most common subtype followed by HNF4A-MODY (n = 11), ABCC8-MODY (n = 11), GCK-MODY (n = 6) and HNF1B-MODY (n = 5). For comparison of clinical profile, only the three 'actionable' subtypes - defined as those who may respond to sulphonylureas, namely, HNF1A, HNF4A and ABCC8-MODY, were included. Age at onset of diabetes was lower among HNF4A-MODY and HNF1A-MODY than ABCC8-MODY, T1D and T2D. Prevalence of retinopathy and nephropathy was higher among the three MODY subtypes taken together (n = 47) as compared to T1D (n = 86) and T2D (n = 86).

CONCLUSION

This is one of the first reports of MODY subtypes from India based on ACMG and gnomAD criteria. The high prevalence of retinopathy and nephropathy in MODY points to the need for earlier diagnosis and better control of diabetes in individuals with MODY.

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.

Microdeletions at 19p13.11p12 in five individuals with neurodevelopmental delay

Only few copy number variants at chromosome 19p13.11 have been reported, thus associated clinical information is scarce. Proximal to these copy number losses, we now identified deletions in five unrelated individuals with neurodevelopmental disorders. They presented with psychomotor delay as well as behavioral and sleeping disorders, while complex cardiovascular, skeletal, and various other malformations were more variable. Dysmorphic features were rather unspecific and not considered as a recognizable gestalt. Neither of the analyzed parents carried their offsprings' deletions, indicating de novo occurrence. The deletion sizes ranged between 0.7 and 5.2 Mb, were located between 18 and 24 megabases from the telomere, and contained a variable number of protein-coding genes (n = 25-68). Although not all microdeletions shared a common region, the smallest common overlap of some of the deletions provided interesting insights in the chromosomal region 19p13.11p12. Diligent literature review using OMIM and Pubmed did not identify a satisfying candidate gene for neurodevelopmental disorders. In the literature, a de novo in-frame deletion in MAU2 was considered pathogenic in an individual with Cornelia de Lange syndrome. Therefore, the clinical differential diagnosis of this latter syndrome in one individual and the encompassment of MAU2 in three individuals' deletions suggest clinical and genetic overlap with this specific syndrome. Three of the four here reported individuals with deletion encompassing GDF1 had different congenital heart defects, suggesting that this gene's haploinsufficiency might contribute to the cardiovascular phenotype, however, with reduced penetrance. Our findings indicate an association of microdeletions at 19p13.11/ 19p13.11p12 with neurodevelopmental disorders, variable symptoms, and malformations, and delineate the phenotypic spectrum of deletions within this genomic region.

Potter Deformation Sequence Caused by 17q12 Deletion: A Lethal Constellation

17q12 deletion syndrome causes developmental abnormalities of the kidneys, pancreas, genital tract, and neurodevelopment, and it has a wide range of phenotypes ranging from fetal demise to normal adulthood with minimal renal impairment. Here we describe a rare case of 17q12 deletion diagnosed prenatally, complicated by anhydramnios and Potter sequence. The baby was born but necessitated life-saving interventions due to pulmonary and renal insufficiency and ultimately succumbed to multi-organ failure. We present full autopsy results describing findings linked to 17q12 deletion, including severe bilateral multicystic renal dysplasia, pancreatic hypoplasia, and cysts adjacent to the Fallopian tubes. We also describe pulmonary hypoplasia and Potter facies as consequences of anhydramnios. We correlate these findings to our current understanding of molecular signals altered by 17q12 deletion, notably affecting HNF1B and LHX1 genes, which are known to mediate renal and genitourinary tract development.

17q12 Microdeletion Syndrome as a Rare Cause of Elevated Liver Enzymes: Case Report and Literature Review

17q12 deletion syndrome is a rare autosomal dominant inherited condition. It results from de novo mutation and can occur without a family history. Hepatocyte nuclear factor-1 beta (HNF1B) and LIM homeobox 1 (LXH1) genes are the most common genes to be deleted in this syndrome. It has unique clinical characteristics involving multiple systems in the body. The most common presentations are usually renal involvement and maturity-onset diabetes of the young type 5 (MODY5). Genetic study is the golden tool to diagnose patients with this syndrome. Our case presents the unique clinical features of 17q12 deletion syndrome along with a literature review.

Recurrent 17q12 microduplications contribute to renal disease but not diabetes

BACKGROUND

17q12 microdeletion and microduplication syndromes present as overlapping, multisystem disorders. We assessed the disease phenotypes of individuals with 17q12 CNV in a population-based cohort.

METHODS

We investigated 17q12 CNV using microarray data from 450 993 individuals in the UK Biobank and calculated disease status associations for diabetes, liver and renal function, neurological and psychiatric traits.

RESULTS

We identified 11 17q12 microdeletions and 106 microduplications. Microdeletions were strongly associated with diabetes (p=2×10^-7) but microduplications were not. Estimated glomerular filtration rate (eGFR mL/min/1.73 m²) was consistently lower in individuals with microdeletions (p=3×10^-12) and microduplications (p=6×10^-25). Similarly, eGFR <60, including end-stage renal disease, was associated with microdeletions (p=2×10^-9, p<0.003) and microduplications (p=1×10^-9, p=0.009), respectively, highlighting sometimes substantially reduced renal function in each. Microduplications were associated with decreased fluid intelligence (p=3×10^-4). SNP association analysis in the 17q12 region implicated changes to HNF1B as causing decreased eGFR (NC_000017.11:g.37741642T>G, rs12601991, p=4×10^-21) and diabetes (NC_000017.11:g.37741165C>T, rs7501939, p=6×10^-17). A second locus within the region was also associated with fluid intelligence (NC_000017.11:g.36593168T>C, rs1005552, p=6×10^-9) and decreased eGFR (NC_000017.11:g.36558947T>C, rs12150665, p=4×10^-15).

CONCLUSION

We demonstrate 17q12 microdeletions but not microduplications are associated with diabetes in a population-based cohort, likely caused by HNF1B haploinsufficiency. We show that both 17q12 microdeletions and microduplications are associated with renal disease, and multiple genes within the region likely contribute to renal and neurocognitive phenotypes.

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.

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.

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.