Familial Kagami-Ogata syndrome in Chinese

Prenatal diagnosis of recurrent Kagami-Ogata syndrome inherited from a mother affected by Temple syndrome: a case report and literature review

BACKGROUND

Kagami-Ogata syndrome (KOS) and Temple syndrome (TS) are two imprinting disorders characterized by the absence or reduced expression of maternal or paternal genes in the chromosome 14q32 region, respectively. We present a rare prenatally diagnosed case of recurrent KOS inherited from a mother affected by TS.

CASE PRESENTATION

The woman's two affected pregnancies exhibited recurrent manifestations of prenatal overgrowth, polyhydramnios, and omphalocele, as well as a small bell-shaped thorax with coat-hanger ribs postnatally. Prenatal genetic testing using a single-nucleotide polymorphism array detected a 268.2-kb deletion in the chromosome 14q32 imprinted region inherited from the mother, leading to the diagnosis of KOS. Additionally, the woman carried a de novo deletion in the paternal chromosome 14q32 imprinted region and presented with short stature and small hands and feet, indicating a diagnosis of TS.

CONCLUSIONS

Given the rarity of KOS as an imprinting disorder, accurate prenatal diagnosis of this rare imprinting disorder depends on two factors: (1) increasing clinician recognition of the clinical phenotype and related genetic mechanism, and (2) emphasizing the importance of imprinted regions in the CMA workflow for laboratory analysis.

Case report: Prenatal diagnosis of Kagami–Ogata syndrome in a Chinese family

The aim of this work was to explore the genetic cause of the proband (Ⅲ2) presenting with polyhydramnios and gastroschisis. Copy number variation sequencing (CNV-seq), methylation-specific multiplex PCR (MS-PCR), and methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) were used to characterize the genetic etiology. CNV-seq revealed a deletion of 732.26 kb at 14q32.2q32.31 in the proband (Ⅲ2) and its mother (Ⅱ2). MS-PCR showed the maternal allele was missing in the proband, while paternal allele was missing in its mother. MS-MLPA showed deletion of the DLK1, MEG3, MIR380, and RTL1 genes of both the proband and its mother. MEG3 imprinting gene methylation increased in the proband, while decreased in its mother. It was indicated that a maternally transmitted deletion was responsible for Kagami–Ogata syndrome in the proband (Ⅲ2), and the de novo paternal deletion resulted in Temple syndrome in the mother (Ⅱ2). Prenatal diagnosis was provided at 17+3 weeks of pregnancy on the mother’s fourth pregnancy (Ⅲ4). Fortunately, the karyotype and single-nucleotide polymorphism array (SNP array) results were normal. The current investigation provided the detection methods for imprinted gene diseases, expanded the phenotype spectrum of the disease, and obtained the insight into the diagnosis, prenatal diagnosis, and genetic counseling of the disease.

Temple syndrome and Kagami-Ogata syndrome: clinical presentations, genotypes, models and mechanisms

Temple syndrome (TS) and Kagami-Ogata syndrome (KOS) are imprinting disorders caused by absence or overexpression of genes within a single imprinted cluster on human chromosome 14q32. TS most frequently arises from maternal UPD14 or epimutations/deletions on the paternal chromosome, whereas KOS most frequently arises from paternal UPD14 or epimutations/deletions on the maternal chromosome. In this review, we describe the clinical symptoms and genetic/epigenetic features of this imprinted region. The locus encompasses paternally expressed protein-coding genes (DLK1, RTL1 and DIO3) and maternally expressed lncRNAs (MEG3/GTL2, RTL1as and MEG8), as well as numerous miRNAs and snoRNAs. Control of expression is complex, with three differentially methylated regions regulating germline, placental and tissue-specific transcription. The strong conserved synteny between mouse chromosome 12aF1 and human chromosome 14q32 has enabled the use of mouse models to elucidate imprinting mechanisms and decipher the contribution of genes to the symptoms of TS and KOS. In this review, we describe relevant mouse models and highlight their value to better inform treatment options for long-term management of TS and KOS patients.

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.

A Male Case of Kagami-Ogata Syndrome Caused by Paternal Unipaternal Disomy 14 as a Result of a Robertsonian Translocation

Kagami-Ogata syndrome (KOS) is a rare imprinting disorder characterized by skeletal abnormalities, dysmorphic facial features, growth retardation and developmental delay. 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 seventy KOS cases have been reported thus far; however, only 10, including two familial, are associated with upd(14)pat harboring Robertsonian translocation (ROB). Here, we reported a male infant with clinical manifestations of facial dysmorphism, bell-shaped small thorax, and omphalocele. Karyotype analyses identify a balanced ROB involving the long arms of chromosomes 13 and 14 both in the patient and his father. We further confirm the pattern of upd(14)pat utilizing DNA polymorphic markers. In conclusion, our case report provides a new male KOS case caused by upd(14)pat with paternally inherited Robertsonian translocation, which represents the second male case officially reported. Notably, a KOS case due to upd(14)pat and ROB is rare. An accurate diagnosis requires not only the identification of the characteristic clinical features but also systemic cytogenetic and molecular studies.