• Journal of Genetic Medicine
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• 제14권1호
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• pp.31-33
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• 2017

Chromosomal loss in trisomy (trisomy rescue) to generate a disomic fetus can cause confined placental mosaicism and/or feto/placental mosaicism. After trisomy rescue event, there is a risk of fetal uniparental disomy (UPD). Noninvasive prenatal test (NIPT) reflects the genomic constitution of the placenta, not of the fetus itself. Feto-placental discrepancy can therefore cause false-positive (trisomy) NIPT results. These discordant NIPT results can serve as important clues to find UPD associated with confined placental mosaicism. We report a case with maternal UPD of chromosome 20, detected by NIPT of 1,000 high-risk pregnancies, carried out for detecting chromosomal abnormalities in Koreans.

• Journal of Genetic Medicine
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• 제17권2호
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• pp.83-88
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• 2020

Silver-Russell syndrome (SRS) is a rare genetic disorder characterized by intrauterine growth restriction, poor postnatal growth, relative macrocephaly, a triangular face, body asymmetry, and feeding difficulties. It is primarily diagnosed according to a clinical scoring system; however, the clinical diagnosis is confirmed with molecular testing, and the disease is stratified into the specific molecular subtypes. SRS is a genetically heterogeneous condition. The major molecular changes are hypomethylation of imprinting control region 1 in 11p15.5 and maternal uniparental disomy of chromosome 7 (UPD(7)mat). Therefore, first-line molecular testing should include methylation-specific approaches for these regions. Here, we report an extremely low birth weight (ELBW) infant with intrauterine growth retardation, postnatal growth retardation, and dysmorphic facial appearance-characteristics consistent with the clinical diagnostic criteria of SRS. Methylation-specific molecular genetic analysis revealed UPD(7)mat, while the loss of heterozygosity was not detected on chromosomal microarray analysis. We present a case of SRS with suspected uniparental heterodisomy of chromosome 7 in an ELBW infant.

• 대한유전성대사질환학회지
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• 제20권2호
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• pp.44-49
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• 2020

가성부갑상샘기능저하증(pseudohypoparathyroidism, PHP)은 부갑상샘호르몬에 대해 표적 기관이 저항성을 가지며, 저칼슘혈증과 고인산혈증을 특징으로 하는 질병이다. PHP의 원인은 자극형 G 단백의 신호전달이 문제인데, α-아형을 인코딩하는 GNAS 유전자와 GNAS 유전자 상부의 각인 이상으로 발생한다. 가족력 없이 발생하는 산발성 PHP 1b형은 GNAS 유전자 상류 다발 지역의 메칠화 이상으로, 그 중 일부는 모계 유전형이 소실되고, 부계 유전형만이 표현된다. 본 논문에서는 간헐적 강직을 주소로 내원한 10.8세 남아에서 발생한 20번 염색체 장완의 부계 단친성 이염색체에 의한 산발성 PHP 1b형의 증례를 고찰해보고자 한다.

• Journal of Genetic Medicine
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• 제14권1호
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• pp.18-22
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• 2017

Pseudohypoparathyroidism type 1b (PHP 1b) is the result of end organ resistance to parathyroid hormone (PTH) in the absence of any features of Albright's hereditary osteodystrophy. There are two subtypes of PHP 1b with different genetic mechanisms. One subtype is related to a maternally derived 3kb microdeletion involving STX 16 gene, and is inherited in an autosomal dominant mode. Familial autosomal dominant inheritance of PHP 1b is relatively rare. The other subtype is associated with more extensive loss of imprinting at the GNAS locus that affects at least one additional differential methylated (hypermethylation at neuroendocrine secretory protein and hypomethylation at antisense transcript and or extra-large stimulatory G protein region) without microdeletion of the STX 16 or AS gene. It can be sporadic due to an imprinting defect in the GNAS gene. In our case, an 8-year-old girl was referred for suspected PHP with no feature of Albright hereditary osteodystrophy. Blood test results revealed hypocalcemia and hyperphosphatemia. Elevated PTH was also checked. There was no family history of endocrine or developmental problem. Her intelligence was normal, but she had inferior sociability at that time. Based on above, we diagnosed a rare case of paternal uniparental disomy of the long arm of chromosome 20 as the cause of PHP 1b by microsatellite marker test of chromosome 20.

• BMB Reports
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• 제37권5호
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• pp.522-526
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• 2004

Prader-Willi (PWS) and Angelman (AS) are syndromes of developmental impairment that result from the loss of expression of imprinted genes in the paternal (PWS) or maternal (AS) 15q11-q13 chromosome. Diagnosis on a clinical basis is difficult in newborns and young infants; thus, a suitable molecular test capable of revealing chromosomal abnormalities is required. We used a variety of cytogenetic and molecular approaches, such as, chromosome G banding, fluorescent in situ hybridization, a DNA methylation test, and a set of chromosome 15 DNA polymorphisms to characterize a cohort of 27 PWS patients and 24 suspected AS patients. Molecular analysis enabled the reliable diagnosis of 14 PWS and 7 AS patients, and their classification into four groups: (A) 6 of these 14 PWS subjects (44%) had deletions of paternal 15q11-q13; (B) 4 of the 7 AS patients had deletions of maternal 15q11-q13; (C) one PWS patient (8%) had a maternal uniparental disomy (UPD) of chromosome 15; (D) the remaining reliably diagnoses of 7 PWS and 3 AS cases showed abnormal methylation patterns of 15q11-q13 chromosome, but none of the alterations shown by the above groups, although they may have harbored deletions undetected by the markers used. This study highlights the importance of using a combination of cytogenetic and molecular tests for a reliable diagnosis of PWS or AS, and for the identification of genetic alterations.

• Journal of Genetic Medicine
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• 제20권1호
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• pp.25-29
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• 2023

The CYP11A1 gene encodes for the cholesterol side-chain cleavage enzyme (P450scc), which initiates steroid hormone biosynthesis. Defective P450scc activity results in severe glucocorticoid and mineralocorticoid deficiencies. We describe a case of P450scc deficiency due to a novel homozygous CYP11A1 variant inherited from the mother with a possibility of uniparental disomy (UPD). The patient was a female, had no family history of endocrine disease, and showed adrenal insufficiency at 13 days of age. Hormonal analysis with an adrenocorticotropic hormone stimulation test showed both glucocorticoid and mineralocorticoid deficiencies, presumed to be a defect of the early stage of steroidogenesis. Exome sequencing reported a novel homozygous frameshift variant of CYP11A1 (c.284_285del, p.Asn95Serfs*10), which was inherited from the mother. Additionally, homozygosity in 15q22.31q26.2, which included CYP11A1, was identified using a chromosomal microarray. It was suggested that the possibility of maternal UPD was involved as the cause of a P450scc deficiency by unmasking the maternally derived affected allele. To our understanding, P450scc deficiency associated with UPD encompassing CYP11A1 had not been reported in Korea before. Genetic analysis can help diagnose rare causes of primary adrenal insufficiency, including P450scc deficiency.

• Journal of Genetic Medicine
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• 제18권1호
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• pp.24-30
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• 2021

Epigenetics deals with modifications in gene expression, without altering the underlying DNA sequence. Genomic imprinting is a complex epigenetic phenomenon that refers to parent-of-origin-specific gene expression. Beckwith-Wiedemann syndrome (BWS) and Silver-Russell syndrome (SRS) are congenital imprinting disorders with mirror opposite alterations at the genomic loci in 11p15.5 and opposite phenotypes. BWS and SRS are important imprinting disorders with the increase of knowledge of genetic and epigenetic mechanisms. Altered expression of the imprinted genes in 11p15.5, especially IGF2 and CDKN1C, affects fetal and postnatal growth. A wide range of imprinting defects at multiple loci, instead of a restricted locus, has been shown in some patients with either BWS or SRS. The development of new high-throughput assays will make it possible to allow accurate diagnosis, personalized therapy, and informative genetic counseling.

• 대한장애인치과학회지
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• 제12권1호
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• pp.11-15
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• 2016

저자는 엔젤만 증후군 중 그 발생 기전이 2% 이하인 편친 이염색체성 엔젤만 증후군 증례를 안전하고 효과적으로 치료하였기에 이를 보고하는 바이다. 환자는 근육간대경련발작(myoclonic seizure)의 병력으로, 조절을 위해 항경련제(Valproate)를 복용중이었고, 전반적인 발육 장애와 지적 장애, 언어 장애를 나타내고 있었다. 구내 소견으로는 치간 이개, 하악골 전돌, 거대설과 연하 장애가 관찰되었으며, 잦은 불수의적 운동 때문에 구강 위생 상태는 매우 불량 하였다. 치료 범위가 광범위하고, 환자의 협조도를 얻을 수 없었으며, GABA 수용체의 기능장애로 인해 진정 약물을 이용한 행동 조절은 효과적이지 않을 것으로 판단하여 전신마취 하에서 치과치료를 시행하였고, 성공적으로 치과치료가 가능했다. 엔젤만 증후군 환자들도 정기적인 치과 방문을 통한 구강 위생 교육, 전문가 치면 세마, 불소 도포가 이루어진다면 적절한 구강 건강을 유지할 수 있으며, 주기적인 치과 방문을 통해 환자가 치과 진료에 적응 한 뒤에는 간단한 치료도 가능하다.

• Clinical and Experimental Pediatrics
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• 제54권2호
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• pp.55-63
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• 2011

Prader-Willi syndrome (PWS) is a complex multisystem genetic disorder that is caused by the lack of expression of paternally inherited imprinted genes on chromosome 15q11-q13. This syndrome has a characteristic phenotype including severe neonatal hypotonia, early-onset hyperphagia, development of morbid obesity, short stature, hypogonadism, learning disabilities, behavioral problems, and psychiatric problems. PWS is an example of a genetic condition caused by genomic imprinting. It can occur via 3 main mechanisms that lead to the absence of expression of paternally inherited genes in the 15q11.2-q13 region: paternal microdeletion, maternal uniparental disomy, and an imprinting defect. Over 99% of PWS cases can be diagnosed using DNA methylation analysis. Early diagnosis of PWS is important for effective long-term management. Growth hormone (GH) treatment improves the growth, physical phenotype, and body composition of patients with PWS. In recent years, GH treatment in infants has been shown to have beneficial effects on the growth and neurological development of patients diagnosed during infancy. There is a clear need for an integrated multidisciplinary approach to facilitate early diagnosis and optimize management to improve quality of life, prevent complications, and prolong life expectancy in patients with PWS.

• Journal of mucopolysaccharidosis and rare diseases
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• 제5권1호
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• pp.29-33
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• 2021

Prader-Willi Syndrome (PWS) is a neurodevelopmental genomic imprinting disorder involving a lack of gene expression from the paternal chromosome 15q11-q13 region. This is typically due to paternal 15q11-q13 deletions (in approximately 60% of cases), maternal uniparental disomy 15, or when both 15s are from the mother (about 35% of cases). An imprinting center controls the expression of imprinted genes in the chromosome 15q11-q13 region. PWS is a neurodevelopmental disorder characterized by mental retardation and distinct physical, behavioral, and psychiatric features. Characteristic behavioral disturbances in PWS include excessive interest in food, skin picking, difficulty with a change in routine, temper tantrums, obsessive and compulsive behaviors, and mood fluctuations. Individuals with PWS typically have intellectual disabilities (borderline to mild/moderate mental retardation) and exhibit a higher overall level of behavior disturbances compared to individuals with similar intellectual disabilities. This condition severely limits social adaptations and quality of life. Different factors have been linked to the intensity and form of these behavioral disturbances, but there is no consensus regarding the cause. Consequently, there is still controversy surrounding management strategies and there is a need for new data. PWS is a multisystem disorder. Family members, caregivers, physicians, dieticians, and speech-language pathologists all play an important role in the management and treatment of symptoms in an individual with PWS. Here we analyze behavioral problems in children and adults with PWS by age and review appropriate management and treatment strategies for these symptoms.