Prenatal findings of paternal uniparental disomy 14: Report of four patients

Quantitative assessment of coat-hanger ribs detected on three-dimensional ultrasound for prenatal diagnosis of Kagami-Ogata syndrome

Kagami-Ogata syndrome (KOS14) is a rare disease characterized by omphalocele, polyhydramnios and a bell-shaped thorax. Although the coat-hanger appearance of the ribs on postnatal X-rays is a key diagnostic finding of KOS14, its prenatal diagnosis remains challenging. We encountered a case of KOS14 diagnosed prenatally that showed omphalocele, polyhydramnios, and a bell-shaped narrow thorax. The coat-hanger angle (CHA) measured at the sixth thoracic vertebrae and the ribs using three-dimensional (3D) ultrasonography was 39°, reflecting the coat-hanger appearance of the ribs. Segmental uniparental disomy chromosome 14 (UPD(14)pat) was confirmed by a methylation analysis and microsatellite analysis after birth. The median CHA (minimum, maximum) in 25 normal fetuses was 19 (9, 26) degrees, and a sonographic CHA of 30° may be a border value for diagnosing KOS14. When the combination of omphalocele and polyhydramnios is found prenatally, 3D ultrasonography for CHA might aid in the differential diagnosis of KOS14.

Prenatal diagnosis of Kagami-Ogata syndrome

Kagami-Ogata syndrome (KOS14) is a rare congenital disorder associated with defective genomic imprinting of the chromosome 14q32 domain. Typical features include polyhydramnios, small and bell-shaped thorax, coat-hanger ribs, dysmorphic facial features, abdominal wall defects, placentomegaly, severe postnatal respiratory distress and intellectual disability. To the best of our knowledge, this may be the first case where ultrasound findings such as: severe polyhydramnios, a small bell-shaped thorax, a protuberant abdomen and characteristic dysmorphic face prompted directed family interrogation finally leading to the prenatal diagnosis of KOS14.

Kagami-Ogata Syndrome: Case Series and Review of Literature

Kagami-Ogata syndrome (KOS) (OMIM #608149) is a genetic imprinting disorder affecting chromosome 14 that results in a characteristic phenotype consisting of typical facial features, skeletal abnormalities including rib abnormalities described as "coat hanger ribs," respiratory distress, abdominal wall defects, polyhydramnios, and developmental delay. First identified by Wang et al in 1991, over 80 cases of KOS have been reported in the literature. KOS, however, continues to remain a rare and potentially underdiagnosed disorder. In this report, we describe two unrelated male infants with differing initial presentations who were both found to have the characteristic "coat hanger" rib appearance on chest X-ray, raising suspicion for KOS. Molecular testing confirmed KOS in each case. In addition to these new cases, we reviewed the existing cases reported in literature. Presence of polyhydramnios, small thorax, curved ribs, and abdominal wall defects must alert the perinatologist toward the possibility of KOS to facilitate appropriate molecular testing. The overall prognosis of KOS remains poor. Early diagnosis allows for counseling by a multidisciplinary team and enables parents to make informed decisions regarding both pregnancy management and postnatal care.

Prenatal Diagnosis of a Mosaic Paternal Uniparental Disomy for Chromosome 14: A Case Report of Kagami-Ogata Syndrome

The Kagami-Ogata syndrome (KOS) is a rare imprinting disorder with a distinct clinical phenotype. In KOS, polyhydramnios is associated with a small bell-shaped thorax and coat-hanger ribs. The genetic etiology of KOS includes paternal uniparental disomy 14 [upd(14)pat], epimutations, and microdeletions affecting the maternally derived imprinted region of chromosome 14q32.2. More than 77 cases of KOS have been reported; however, only one mosaic upd(14)pat case has been reported. Here we report a second mosaic upd(14)pat case. The prognosis of upd(14)pat patients is poor because of severe respiratory insufficiency. We summarized prenatal ultrasound findings of KOS to raise awareness of this condition for possible diagnosis of KOS prenatally when polyhydramnios combination with a small bell-shaped thorax and other related features are first observed. Prenatal diagnosis using methylation-specific multiplex ligation-dependent probe amplification (MLPA) or a single-nucleotide polymorphism-based microarray analysis is recommended.

Kagami-Ogata syndrome: an important differential diagnosis to Beckwith-Wiedemann syndrome

We report the case of a fetus with sonographic characteristics of Beckwith-Wiedemann syndrome (BWS). A 30-year-old gravida 2 para 1 was referred to our fetal medicine unit with an omphalocele. Fetal macrosomia, organomegaly, and polyhydramnios but no macroglossia were detected and BWS was suspected. Genetic testing for BWS did not confirm the suspected diagnosis as the karyotype was normal. Symptomatic polyhydramnios led to repeated amnioreductions. At 35 + 5 weeks of gestation, a female neonate of 3660 g was delivered with APGAR scores of 6/7/8, after 1/5/10 min, respectively. The abnormal shape of the thorax, facial dysmorphism, need for ventilation, and generalized muscular hypotonia led to the suspicion of Kagami-Ogata syndrome (KOS), which was confirmed by genetic testing. KOS in our patient was caused by a large deletion in the MEG3-region on chromosome 14q32 affecting the maternal allele. In this report, we highlight the notion that when sonographic signs suggestive of BWS such as macrosomia, polyhydramnios, and omphalocele are present and genetic testing does not confirm the suspected diagnosis, KOS should be tested for.

DLK1-DIO3 imprinted locus deregulation in development, respiratory disease, and cancer

INTRODUCTION

The imprinted DLK1-DIO3 locus at 14q32.1-32.31 holds biological significance in fetal development, whereby imprinting errors are causal to developmental disorders. Emerging evidence has implicated this locus in other diseases including cancer, highlighting the biological parallels between fetal organ and tumour development. Areas covered: Controlled regulation of gene expression from the imprinted DLK1-DIO3 locus at 14q32.1-32.31 is crucial for proper fetal development. Deregulation of locus gene expression due to imprinting errors has been mechanistically linked to the developmental disorders Kagami-Ogata Syndrome and Temple Syndrome. In adult tissues, deregulation of locus genes has been associated with multiple malignancies although the causal genetic mechanisms remain largely uncharacterised. Here, we summarize the genetic mechanisms underlying the developmental disorders that arise as a result of improper locus imprinting and the resulting developmental phenotypes, emphasizing both the coding and noncoding components of the locus. We further highlight biological parallels common to both fetal development and disease, with a specific focus on lung development, respiratory disease, and lung cancer. Expert commentary: Many commonalities between respiratory and developmental defects have emerged with respect to the 14q32 locus, emphasizing the importance of studying the effects of imprinting on gene regulation patterns at this locus in both biological settings.

Prenatal findings and epimutations for paternal uniparental disomy for chromosome 14 syndrome

The phenotypes associated with paternal uniparental disomy for chromosome 14 (UPD(14)pat) are clinically distinctive and caused by genetic alterations at the 14q32.2 imprinted region. Here we describe prenatal and neonatal findings in a case of epimutation associated with UPD(14)pat-like phenotype. A 25-year-old Japanese woman was referred to hospital at 32 weeks of gestation for management of threatened premature delivery. Fetal ultrasound and magnetic resonance imaging showed a narrow thorax and polyhydramnios. At 35 weeks of gestation, emergency cesarean section was performed and placentomegaly was identified. Physical examination of the neonate indicated a small narrow thorax, diastasis recti, and dysmorphic facial features that included hirsute forehead, broad flat nasal bridge, micrognathia, small ears, and a long protruding philtrum. Genetic analysis identified epimutation at the intergenic differentially methylated region (IG-DMR) and at MEG3-DMR.

Hepatoblastoma in an infant with paternal uniparental disomy 14

A 29-year-old primigravida developed polyhydramnios at 24 weeks of gestation, requiring six serial amnioreductions. In addition, prenatal ultrasound examinations revealed a fetus with small stomach pouch, small thorax, slightly shortened limbs, and skin edema; paternal uniparental disomy 14(upd(14)pat) phenotype was suspected. At 37 weeks, the patient delivered a 2558 g female infant with characteristic facial features, webbed neck, thoracic deformity, abdominal wall defect, skin edema, overlapping fingers, placentomegaly, and small thorax with 'coat-hanger' appearance of the ribs on chest X-ray. A phenotype consistent with upd(14)pat was confirmed by DNA analysis. Although the infant's condition was initially stable, hepatoblastoma was subsequently detected and right hepatectomy was performed on day 224. On day 382, the infant was discharged with in-home respiratory management.

Paternal uniparental disomy 14 and related disorders: placental gene expression analyses and histological examinations

Although recent studies in patients with paternal uniparental disomy 14 [upd(14)pat] and other conditions affecting the chromosome 14q32.2 imprinted region have successfully identified underlying epigenetic factors involved in the development of upd(14)pat phenotype, several matters, including regulatory mechanism(s) for RTL1 expression, imprinting status of DIO3 and placental histological characteristics, remain to be elucidated. We therefore performed molecular studies using fresh placental samples from two patients with upd(14)pat. We observed that RTL1 expression level was about five times higher in the placental samples of the two patients than in control placental samples, whereas DIO3 expression level was similar between the placental samples of the two patients and the control placental samples. We next performed histological studies using the above fresh placental samples and formalin-fixed and paraffin-embedded placental samples obtained from a patient with a maternally derived microdeletion involving DLK1, the-IG-DMR, the MEG3-DMR and MEG3. Terminal villi were associated with swollen vascular endothelial cells and hypertrophic pericytes, together with narrowed capillary lumens. DLK1, RTL1 and DIO3 proteins were specifically identified in vascular endothelial cells and pericytes, and the degree of protein staining was well correlated with the expression dosage of corresponding genes. These results suggest that RTL1as-encoded microRNA functions as a repressor of RTL1 expression, and argue against DIO3 being a paternally expressed gene. Furthermore, it is inferred that DLK1, DIO3 and, specially, RTL1 proteins, play a pivotal role in the development of vascular endothelial cells and pericytes.

Radiological evaluation of dysmorphic thorax of paternal uniparental disomy 14

BACKGROUND

The "coat-hanger" sign of the ribs with a bell-shaped thorax has been known as a radiological hallmark of the paternal uniparental disomy 14 (upd(14)pat).

OBJECTIVE

To quantitatively determine the differences in thoracic deformity between upd(14)pat and other bone diseases with thoracic hypoplasia and to establish the age-dependent evolution.

MATERIALS AND METHODS

The subjects comprised 11 children with upd(14)pat. The angle between the 6th posterior rib and the horizontal axis was measured (coat hanger angle; CHA). The ratio of the mid- to widest thorax diameter (M/W ratio) was calculated for the bell-shaped thorax.

RESULTS

CHA ranged from +28.5 to 45° (mean; 35.1° ± 5.2) in upd(14)pat, and from -19.8 to 21° (-3.3 ± 13°) in bone dysplasias (p < 0.01). The M/W ratio ranged from 58% to 93% (75.4 ± 10) in upd(14)pat, and from 80% to 92% (86.8 ± 3.3) in bone dysplasias (p < 0.05). Serial radiographs revealed that CHA remained constant during early childhood, while the M/W ratio gradually increased with age.

CONCLUSION

The "coat-hanger" sign of upd(14)pat provides a distinctive radiological gestalt that makes it possible to differentiate the disorder from other skeletal dysplasias. By contrast, the bell-shaped thorax is significant only in the neonatal period.