Single-cell RNA sequencing reveals cellular and molecular landscape of fetal cystic hygroma.

BACKGROUND: The molecular mechanism of fetal cystic hygroma (CH) is still unclear, and no study has previously reported the transcriptome changes of single cells in CH. In this study, single-cell transcriptome sequencing (scRNA-seq) was used to investigate the characteristics of cell subsets in the lesion tissues of CH patients. METHODS: Lymphoid tissue collected from CH patients and control donors for scRNA-seq analysis. Differentially expressed gene enrichment in major cell subpopulations as well as cell-cell communication were analyzed. At the same time, the expression and interactions of important VEGF signaling pathway molecules were analyzed, and potential transcription factors that could bind to KDR (VEGFR2) were predicted. RESULTS: The results of scRNA-seq showed that fibroblasts accounted for the largest proportion in the lymphatic lesions of CH patients. There was a significant increase in the proportion of lymphatic endothelial cell subsets between the cases and controls. The VEGF signaling pathway is enriched in lymphatic endothelial cells and participates in the regulation of cell-cell communication between lymphatic endothelial cells and other cells. The key regulatory gene KDR in the VEGF signaling pathway is highly expressed in CH patients and interacts with other differentially expressed EDN1, TAGLN, and CLDN5 Finally, we found that STAT1 could bind to the KDR promoter region, which may play an important role in promoting KDR up-regulation. CONCLUSION: Our comprehensive delineation of the cellular composition in tumor tissues of CH patients using single-cell RNA-sequencing identified the enrichment of lymphatic endothelial cells in CH and highlighted the activation of the VEGF signaling pathway in lymphoid endothelial cells as a potential modulator. The molecular and cellular pathogenesis of fetal cystic hygroma (CH) remains largely unknown. This study examined the distribution and gene expression signature of each cell subpopulation and the possible role of VEGF signaling in lymphatic endothelial cells in regulating the progression of CH by single-cell transcriptome sequencing. The enrichment of lymphatic endothelial cells in CH and the activation of the VEGF signaling pathway in lymphatic endothelial cells provide some clues to the pathogenesis of CH from the perspective of cell subpopulations.

Early prenatal diagnosis of causative homozygous variants in ASCC1 in a fetus with cystic hygroma and additional homozygous variants of unknown significance associated with a neurological phenotype not visible in early gestation: Dual diagnosis or not?

A consanguineous couple was referred at 10 weeks of gestation (WG) for prenatal genetic investigations due to isolated cystic hygroma. Prenatal trio exome sequencing identified causative homozygous truncating variants in ASCC1 previously implicated in spinal muscular atrophy with congenital bone fractures. Prenatal manifestations in ASCC1 can usually include hydramnios, fetal hypo-/akinesia, arthrogryposis, contractures and limb deformities, hydrops fetalis and cystic hygroma. An additional truncating variant was identified in CSPP1 associated with Joubert syndrome. Presentations in CSPP1 include cerebellar and brainstem malformations with vermis hypoplasia and molar tooth sign, difficult to visualize in early gestation. A second pregnancy was marked by the recurrence of isolated increased nuchal translucency at 10 + 2 WG. Sanger prenatal diagnosis targeted on ASCC1 and CSPP1 variants showed the presence of the homozygous familial ASCC1 variant. In this case, prenatal exome sequencing analysis is subject to a partial ASCC1 phenotype and an undetectable CSPP1 phenotype at 10 weeks of gestation. As CSPP1 contribution is unclear or speculative to a potentially later in pregnancy or postnatal phenotype, it is mentioned as a variant of uncertain significance. The detection of pathogenic or likely pathogenic variants involved in severe disorders but without phenotype-genotype correlation because the pregnancy is in the early stages or due to prenatally undetectable phenotypes, will encourage the clinical community to define future practices in molecular prenatal reporting.

Retrospective analysis of genetic etiology and obstetric outcome of fetal cystic hygroma: A single-center study.

BACKGROUND: Cystic hygroma (CH) is a relatively common observation in prenatal ultrasounds; however, there are few studies about copy number variations (CNVs) of fetuses with CH. METHODS: We performed a retrospective analysis on 40 pregnant patients (out of 8000 pregnant patients) whose fetuses had CH from November 2016 to June 2021. Villus, amniotic fluid, or umbilical cord blood samples were collected, based on the corresponding gestational age, for karyotype analysis and single-nucleotide polymorphism array (SNP-array). RESULTS: Among the 40 fetuses with CH, 16 (40.0%, 16/40) exhibited isolated CH and 24 (60.0%, 24/40) exhibited CH combined with other ultrasound abnormalities. The most common CH-comorbid ultrasound abnormalities observed in this study were congenital heart disease (25.0%, 6/24), thickened nuchal translucency (20.8%, 5/24), and fetal edema (12.5%, 3/24). Karyotype and SNP-array analysis resulted in an overall detection rate of 30.0% (12/40). Karyotype analysis led to the detection of eight cases of pathogenic CNVs, among which 45, X was the most common. In addition to the above pathogenic CNV, four additional cases were detected by SNP-array. There was no significant difference in the observed pathogenic CNVs between isolated CH and CH combined with other ultrasound (31.3% vs 29.2%, P > .99). Karyotype analysis and SNP-array results influence whether parents terminate the pregnancy. When genetic abnormalities are detected in the fetus, the parents often choose to terminate the pregnancy. CONCLUSIONS: Our study emphasizes that genomic examination should be performed on fetuses with CH to confirm the etiology as soon as possible. During genetic counseling, all fetal characteristics should be carefully and comprehensively evaluated.

Complex rearrangements of Y chromosome suggest RPS4Y1 as lymphedema candidate gene.

OBJECTIVE: Cystic hygromas are frequently encountered in fetus with Turner syndrome (TS). Nevertheless, identification of genetic loci responsible for the cystic hygroma has been problematic. Here, we tried to elucidate the candidate gene for cystic hygroma through a rare case of complex Y chromosomal rearrangements involving duplication of partial Yq and monosomy of partial Yp. CASE REPORT: A 30-year-old woman, gravida 1 para 0, was diagnosed with fetal cystic hygroma at 12 weeks of gestation. The genetic analysis of the product of conception revealed complex rearrangement of Y chromosome: microdeletion in Yp11.2p11.31 and microduplicatin in Yq11.223q11.23. The deleted region spans about 6.25 Mb and includes 76 genes, including SRY. The duplicated region spans about 4.76 Mb and includes 145 genes. CONCLUSION: From this rare case with non-mosaic complex Y-chromosome rearrangements, we could narrow down Turner stigmata critical region to Yp11.2～p11.3. We also propose RPS4Y1 as lymphedema candidate gene.

Long-term outcome of fetus with ameliorated cystic hygroma.

OBJECTIVE: Cystic hygroma often ameliorates or disappears with pregnancy progression. Fetuses/neonates with amelioration, when without chromosomal or major structural abnormality, generally show a favorable outcome at birth. The present study was aimed to clarify the short/long-term outcomes of fetuses/neonates with the amelioration of cystic hygroma during pregnancy. MATERIAL AND METHODS: This was a retrospective observational study. We focused on fetuses with cystic hygroma managed in our institute between January 2006 and June 2019. The infants were followed by pediatricians (neonatologist, pediatric cardiologist, and pediatric neurologist) and pediatric outcomes were retrieved from the medical records up to 3 years old. RESULTS: One hundred and seven fetuses with cystic hygroma were included. Of the 107, cystic hygromas ameliorated in 31 fetuses (31/107: 29%). Of the 31, there were 26 livebirths. Half (n = 13) of the 26 fetuses had a good outcome, whereas the remaining half (n = 13) had abnormalities. Various abnormalities were detected in their infancies. A nuchal thickness (diameter of hygroma) of ≥5 mm was significantly correlated with abnormalities (P = 0.047). CONCLUSION: Physicians should pay attention to fetuses/neonates with ameliorated cystic hygroma. Of those, special attention should be paid to fetuses/neonates with a nuchal thickness at diagnosis ≥5 mm.

Dysregulation of Amphiregulin stimulates the pathogenesis of cystic lymphangioma.

Along with blood vessels, lymphatic vessels play an important role in the circulation of body fluid and recruitment of immune cells. Postnatal lymphangiogenesis commonly occurs from preexisting lymphatic vessels by sprouting, which is induced by lymphangiogenic factors such as vascular endothelial growth factor C (VEGF-C). However, the key signals and cell types that stimulate pathological lymphangiogenesis, such as human cystic lymphangioma, are less well known. Here, we found that mouse dermal fibroblasts that infiltrate to sponges subcutaneously implanted express VEGF-D and sushi, Von Willebrand factor type A, EGF, and pentraxin domain containing 1 (SVEP1) in response to PDGFRß signal. In vitro, Pdgfrb knockout (ß-KO) fibroblasts had reduced expression of VEGF-D and SVEP1 and overproduced Amphiregulin. Dysregulation of these three factors was involved in the cyst-like and uneven distribution of lymphatic vessels observed in the ß-KO mice. Similarly, in human cystic lymphangioma, which is one of the intractable diseases and mostly occurs in childhood, fibroblasts surrounding cystic lymphatics highly expressed Amphiregulin. Moreover, fibroblast-derived Amphiregulin could induce the expression of Amphiregulin in lymphatic endothelial cells. The dual source of Amphiregulin activated EGFR expressed on the lymphatic endothelial cells. This exacerbation cascade induced proliferation of lymphatic endothelial cells to form cystic lymphangioma. Ultimately, excessive Amphiregulin produced by fibroblasts surrounding lymphatics and by lymphatic endothelial cells per se results in pathogenesis of cystic lymphangioma and will be a fascinating therapeutic target of cystic lymphangioma.

Phenotypic and Genomic Analysis of Cystic Hygroma in Pigs.

Cystic hygroma is a malformation of the lymphatic and vascular system and is recognized as a benign congenital tumor that affects humans and animals in the perinatal period. This congeni-tal disorder is rarely described in animals, and until today, cystic hygroma in pigs has not been described in the literature. In a purebred Piètrain litter with twelve live-born piglets, cystic hy-groma was noticed on the rump of two male pigs within the first week of life. In addition, a third case of a crossbred weaner (Large White × Landrace) was detected during a herd examina-tion. To rule out common differential diagnoses, e.g., abscess or hematoma, further clinical and pathological investigations were conducted. During clinical examination, a painless and soft mass, which was compressible, was detected on the rump of all affected animals. The ultra-sonographic examination revealed a fluid-filled and cavernous subcutaneous structure. In addi-tion, a puncture of the cyst was conducted, revealing a serosanguinous fluid with negative bacte-riological culture. In all cases, a necropsy was performed, showing that the animals had fluid-filled cysts lined by well-differentiated lymphatic endothelium. Based on the clinicopathological examination, cystic hygroma was diagnosed. Furthermore, SNP array genotyping and whole-genome sequencing was performed and provided no evidence for a chromosomal disorder. In the Piètrain family, several genome regions were homozygous in both affected piglets. None-theless, a dominant acting de novo germline variant could not be ruled out, and therefore differ-ent filtering strategies were used to find pathogenic variants. The herein presented lists of pri-vate variants after filtering against hundreds of control genomes provide no plausible candidate and no shared variants among the two sequenced cases. Therefore, further studies are needed to evaluate possible genetic etiology. In general, systematic surveillance is needed to identify ge-netic defects as early as possible and to avoid the occurrence of losses in the pig population.

Outcome of 45,X fetuses with cystic hygroma: A systematic review.

This objective of this systematic review was to estimate live birth rate and explore prognostic indicators in fetuses with 45,X karyotype and a posterior cystic hygroma (CH). Electronic databases were searched and studies reporting pregnancy outcomes (termination, spontaneous abortion, demise, or live birth) for fetuses with 45,X karyotype and a CH diagnosed on ultrasound were included. For cases of survival, CH characteristics, presence of hydrops fetalis, or concomitant anomalies, delivery details, and postnatal outcomes were summarized. A total of 95 studies, including 535 cases, met inclusion criteria: 285 (53.3%) pregnancies were terminated, 72 (13.5%) had spontaneous abortion or demise, 164 (30.7%) had unspecified pregnancy failure, and 14 (2.6%) were live births. Among live births with data available, all CH measured 2-7 cm, more than half were septate, and almost all regressed in size or eventually disappeared. Hydrops fetalis was noted in five cases. Of the eight live births with neonatal outcomes available, three neonates died shortly after birth and five survived past the neonatal period. This review suggests that diagnosis of CH in a 45,X fetus is associated with an estimated live birth rate of 2.6%, but only 1% survive to infancy. Prognosis appears to improve with CH regression.

Prenatal diagnosis and management of monozygotic twins discordant for severe fetal abnormalities.

OBJECTIVE: We present prenatal diagnosis and management of monozygotic (MZ) twins discordant for severe fetal abnormalities. CASE REPORT: A 36-year-old woman underwent amniocentesis at 18 weeks of gestation because of advanced maternal age, and hydrops fetalis, a giant cystic hygroma of 5 × 3.5 cm and left hydronephrosis in a co-twin. The other co-twin was structurally normal. Amniocentesis revealed a karyotype of 46,XY in both co-twins. Simultaneous polymorphic DNA marker analysis using the DNAs extracted from maternal blood and uncultured amniocytes confirmed MZ twinning. The woman underwent a successful selective fetal reduction by radiofrequency ablation at 22 weeks of gestation. At 28 weeks of gestation, premature rupture of membranes occurred, and a 1280-g normal male baby and a 275-g dead malformed co-twin were delivered. The normal co-twin was phenotypically normal and was doing well at age seven weeks. CONCLUSIONS: Prenatal diagnosis of MZ twins discordant for structural abnormalities should include a differential diagnosis of MZ twinning, and a zygosity test is necessary under such a circumstance.

First-trimester cystic hygroma and neurodevelopmental disorders: The association to remember.

OBJECTIVE: We present two prenatal cases of first-trimester cystic hygroma who are later found to suffer from rare genetic syndromes. CASE REPORT: Both of the two pregnant women were showed to have fetal cystic hygroma on ultrasound at the first trimester. Fetal microarray result was normal. Follow-up sonographic examinations showed no structural anomalies. The two pregnancies continued uncomplicatedly to term. However, the two infants developed early neurodevelopmental syndrome within two years of age. Exome sequencing confirmed that one child had Mental retardation, autosomal dominant 23 (MRD23) with a c.646delC (p.Q216Sfs∗35) variant in SETD5 gene, and the other child had Smith-Magenis syndrome with a c.3103dupC (Q1035Pfs∗31) variant in RAI1 gene. CONCLUSION: Clinicians have to be vigilant when counseling the patient whose fetus has a first-trimester cystic hygroma even with a normal array result and normal sonographic scans. Although they are rare, monogenetic syndromes are possible outcomes.

A unique case of recurrent fetal cystic hygroma: first fetus with an inherited heteromorphism of chromosome 1 (1qh+) and the second fetus with 69XXX triploidy.

The authors report a unique recurrent septated cystic hygroma (CH), on two successive pregnancies, at five years interval. The chromosome analysis of the first fetus showed an increase in length of heterochromatin on the long arm of chromosome 1 - 1qh+, a chromosomal polymorphism inherited from mother, 46XX,1qh+,14ps+,21ps+. The karyotype of the second CH, with more severe ultrasound (US) imaging, showed a 69XXX triploidy. The patient took no risk and underwent each time a termination of pregnancy (TOP). The first karyotype is generally considered "normal", although there are few reports linking 1qh+ with low fertility, but this was not the case, the patient having, from a previous marriage, a healthy boy and two TOPs. So, this "particular", but "healthy" karyotype was not a cause for the first CH. The second karyotype highlights a possible causality between the 69XXX triploidy, usually associated with partial hydatidiform mole, and a more severe septated CH in the last fetus. Neither the CHs' appearance nor their recurrence seemed to be family linked, as the two CHs had distinct genetic profiles. We recommend that, once CH is diagnosed, a careful US examination is compulsory for the determination of subcutaneous edema, ascites, pleural and pericardial effusions and cardiac or renal abnormalities; an early genetic work-up is mandatory, by chorionic villus sampling or amniocentesis. However, a "healthy" karyotype does not exclude a severe form, as in our first case of CH. Due to the very poor outcome of fetuses with CH, the patient must be thoroughly informed about the short and the long-term fetal prognosis.

Prenatal ultrasound findings of rasopathies in a cohort of 424 fetuses: update on genetic testing in the NGS era.

BACKGROUND: This study evaluates 6 years of prenatal rasopathy testing in the Netherlands, updates on previous data and gives recommendations for prenatal rasopathy testing. METHODS: 424 fetal samples, sent in for prenatal rasopathy testing in 2011-2016, were collected. Cohort 1 included 231 samples that were sequenced for 1-5 rasopathy genes. Cohort 2 included 193 samples that were analysed with a 14-gene next generation sequencing (NGS) panel. For all mutation-positive samples in both cohorts, the referring physician provided detailed ultrasound findings and postnatal follow-up. For 168 mutation-negative samples in cohort 2, solely clinical information on the requisition form was collected. RESULTS: In total, 40 (likely) pathogenic variants were detected (9.4%). All fetuses showed a variable degree of involvement of prenatal findings: increased nuchal translucency (NT)/cystic hygroma, distended jugular lymph sacs (JLS), hydrops fetalis, polyhydramnios, pleural effusion, ascites, cardiac defects and renal anomalies. An increased NT was the most common finding. Eight fetuses showed solely an increased NT/cystic hygroma, which were all larger than 5.5 mm. Ascites and renal anomalies appeared to be poor predictors of pathogenic outcome. CONCLUSION: Fetuses with a rasopathy show in general multiple ultrasound findings. The larger the NT and the longer it persists, the more likely it is to find a pathogenic variant. Rasopathy testing is recommended when the fetus shows an isolated increased NT ≥5.0 mm or when NT of ≥3.5 mm and at least one of the following ultrasound anomalies is present: distended JLS, hydrops fetalis, polyhydramnios, pleural effusion, ascites, cardiac defects and renal anomalies.

Neu-Laxova syndrome presenting prenatally with increased nuchal translucency and cystic hygroma: The utility of exome sequencing in deciphering the diagnosis.

Neu-Laxova syndrome (NLS) is a lethal autosomal recessive microcephaly syndrome associated with intrauterine growth restriction (IUGR) and multiple congenital anomalies. Clinical features include central nervous system malformations, joint contractures, ichthyosis, edema, and dysmorphic facial features. Biallelic pathogenic variants in either the PHGDH or PSAT1 genes have been shown to cause NLS. Using exome sequencing, we aimed to identify the underlying genetic diagnosis in three fetuses (from one family) with prenatal skin edema, severe IUGR, micrognathia, renal anomalies, and arthrogryposis and identified a homozygous c.1A>C (p.Met1?, NM_006623.3) variant in the PHGDH gene. Loss of the translation start codon is a novel genetic mechanism for the development of NLS. Prenatal diagnosis of NLS is challenging and few reports describe the fetal pathology. Fetal neuropathologic examination revealed: delayed brain development, congenital agenesis of the corticospinal tracts, and hypoplasia of the hippocampus, cerebellum and brainstem. Each pregnancy also showed increased nuchal translucency (NT) or cystic hygroma. While NLS is rare, it may be a cause of recurrent increased NT/cystic hygroma. This finding provides further support that cystic hygroma has many different genetic causes and that exome sequencing may shed light on the underlying genetic diagnoses in this group of prenatal patients.

Non-invasive prenatal sequencing for multiple Mendelian monogenic disorders using circulating cell-free fetal DNA.

Current non-invasive prenatal screening is targeted toward the detection of chromosomal abnormalities in the fetus1,2. However, screening for many dominant monogenic disorders associated with de novo mutations is not available, despite their relatively high incidence3. Here we report on the development and validation of, and early clinical experience with, a new approach for non-invasive prenatal sequencing for a panel of causative genes for frequent dominant monogenic diseases. Cell-free DNA (cfDNA) extracted from maternal plasma was barcoded, enriched, and then analyzed by next-generation sequencing (NGS) for targeted regions. Low-level fetal variants were identified by a statistical analysis adjusted for NGS read count and fetal fraction. Pathogenic or likely pathogenic variants were confirmed by a secondary amplicon-based test on cfDNA. Clinical tests were performed on 422 pregnancies with or without abnormal ultrasound findings or family history. Follow-up studies on cases with available outcome results confirmed 20 true-positive, 127 true-negative, zero false-positive, and zero-false negative results. The initial clinical study demonstrated that this non-invasive test can provide valuable molecular information for the detection of a wide spectrum of dominant monogenic diseases, complementing current screening for aneuploidies or carrier screening for recessive disorders.

Cystic Hygroma: A Preliminary Genetic Study and a Short Review from the Literature.

BACKGROUND: The objective of this study is to examine the hypothesis that cystic hygroma (CH) with normal karyotype can manifest as a Mendelian inherited trait, and that a genetic similitude with hereditary lymphedema exists. To reach this goal, we investigated the prevalence of genetic variants in angiogenesis and lymphangiogenesis genes in a cohort of euploid fetuses with CH that almost resolved before delivery. A short review of cases from literature is also reported. METHODS AND RESULTS: Five fetuses were screened using a next-generation sequencing approach by targeting 33 genes known to be associated with vascular and lymphatic malformations. The genetic evaluation revealed two novel variants in KDR and KRIT1 genes. CONCLUSION: A review of the literature to date revealed that an association exists between CH and hereditary lymphedema and, similar to lymphedema, CH can be inherited in autosomal recessive and autosomal dominant manner, with the latter most likely associated with a better prognosis. About KDR and KRIT1 genes, no other similar associations are reported in the literature and caution is needed in their interpretation. In conclusion, we thought that a genetic test for the outcome of familial CH could be of enormous prognostic value.

First trimester cystic hygroma colli: Retrospective analysis in a tertiary center.

OBJECTIVE: This retrospective study aims to evaluate the incidence, presence of chromosomal anomalies and outcome of fetuses diagnosed with cystic hygroma colli in the first trimester in a single tertiary center. STUDY DESIGN: A retrospective study was performed over a ten-years period from 2007 to 2017 of all fetuses with a first-trimester diagnosis of cystic hygroma. Maternal and fetal parameters were assessed with descriptive statistics. RESULTS: A total of 185 singleton pregnancies were included. Chromosomal anomalies were present in 122 cases (65.9%). Sixty-three fetuses (34.1%) had a normal karyotype. Noonan syndrome was diagnosed in 6 cases using additional testing for RASopathies. In euploid fetuses, a major congenital anomaly was detected in 35 of 63 cases (56%) and if present, 91.4% had an abnormal fetal outcome compared to 32.1% if no structural anomaly was found (p < 0.01). Fetuses with a nuchal translucency thickness more than 10 mm and hydropic fetuses had a worse outcome. DISCUSSION: Associated structural anomalies or hydrops fetalis are significant predictors for an abnormal outcome in pregnancies with first-trimester cystic hygroma and a normal karyotype. Cytogenetic evaluation and detailed sonographic evaluation are of great importance in the determination of the prognosis of pregnancies complicated by first-trimester cystic hygroma.

Implications of fetoplacental mosaicism on cell-free DNA testing for sex chromosome aneuploidies.

OBJECTIVE: The unique biological behavior of sex chromosomes has implications for cell-free DNA (cfDNA) testing. Our purpose is to predict the (1) false positive/negative rates of cfDNA testing consequent to fetoplacental mosaicism for any sex chromosome aneuploidies (SCA) and (2) positive predictive value (PPV) and negative predictive values of a high-risk and low-risk cfDNA result for any SCA. METHOD: This is a retrospective analysis of 67 030 chorionic villus sampling karyotypes, including fetoplacental mosaicism cases. RESULTS: Non-mosaic 45, X is associated with cystic hygroma/increased nuchal translucency and fetal anomalies. The false positive rate consequent to confined placental mosaicism is predicted to be 0.05%. The estimated false negative rate is in the range of 0% to 5.7% for all non-mosaic SCAs; it is 70% for mosaic 45, X with normal ultrasound. The predicted PPV on amniocytes is very high for most SCAs (94.4-99.4%). However, the stratified analysis shows that the PPV is much lower for 45, X without ultrasound anomalies compared with 45, X with abnormal scan (51% or 71%, vs 99%, respectively). CONCLUSION: Mosaicism is a major issue for SCA cfDNA testing, and prenatal confirmation, preferentially with amniocentesis if there are no ultrasound anomalies, remains important in counseling. As PPV varies on the basis of the presence of an ultrasound anomaly, skilled evaluation is critical. © 2017 John Wiley & Sons, Ltd.

Detection of mosaic 15q11.1-q11.2 deletion encompassing NBEAP1 and POTEB in a fetus with diffuse lymphangiomatosis.

OBJECTIVE: We present cytogenetic and molecular cytogenetic diagnoses of mosaic deletion of chromosome 15q11.1-q11.2 in a fetus with diffuse lymphangiomatosis. CASE REPORT: A 33-year-old woman underwent amniocentesis at 22 weeks of gestation because of fetal diffuse lymphangiomatosis involving left-side chest, abdominal cavity, thigh and vulva, and intrauterine growth restriction. Amniocentesis revealed a karyotype of 46,XX,del(15) (q11.1q11.2)[9]/46,XX[26]. The mother had a karyotype of 46,XX. The father had a karyotype of 46,XY. The parents elected to terminate the pregnancy. A 610-g female fetus was delivered at 23 weeks of gestation with large cystic lymphangioma over the left abdomen, thigh, and vulva. The umbilical cord had a karyotype of 46,XX,del(15)(q11.1q11.2)[24]/ 46,XX[16]. The placental tissue had a karyotype of 46,XX,del(15)(q11.1q11.2)[23]/ 46,XX[17]. Array comparative genomic hybridization analysis of the umbilical cord and placenta revealed a 2.42-Mb deletion of 15q11.1-q11.2 encompassing the genes of NBEAP1 and POTEB. CONCLUSION: Deletion of 15q11.1-q11.2 encompassing NBEAP1 and POTEB may be associated with diffuse lymphangiomatosis.