• Journal of Interdisciplinary Genomics
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• 제6권1호
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• pp.1-5
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• 2024

Chromosome 22 is an acrocentric chromosome containing 500-600 genes, representing 1.5%-2% of the total DNA in cells. It was the first human chromosome to be fully sequenced by the Human Genome Project. Several syndromes involving the partial deletion or duplication of chromosome 22 are well descibed, including 22q11.2 deletion syndrome, 22q11.2 duplication syndrome, 22q11.2 distal deletion syndrome, Phelan-McDermid syndrome caused by a 22q13 deletion or pathogenic variant in SHANK3, and cat-eye syndrome caused by a 22 pter-q11 duplication. This review aims to provide concise information on the clinical characteristics of these syndromes. In particular, the similarities in features among these syndromes, genetic basis, and standard detection techniques are described, providing guidance for diagnosis and genetic counselling.

• Journal of Genetic Medicine
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• 제12권1호
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• pp.57-60
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• 2015

CHARGE syndrome (coloboma, heart defects, atresia choanae, retarded growth and development, genital hypoplasia, and ear abnormalities) is characterized by multiple malformations and is diagnosed using distinct consensus criteria. Mutations in the gene encoding chromodomain helicase DNA-binding protein 7 (CHD7) are the major cause of CHARGE syndrome. Clinical features of CHARGE syndrome considerably overlap those of 22q11.2 deletion syndrome. Of these features, immunodeficiency and hypocalcemia are frequently reported in patients with 22q11.2 deletion syndrome but are rarely reported in patients with CHARGE syndrome. In this report, we have described the case of a patient with typical phenotypes of 22q11.2 deletion syndrome but without the proven chromosome microdeletion. Mutation analysis of CHD7 identified a pathogenic mutation (c.2238+1G>A) in this patient. To our knowledge, this is the first case of CHARGE syndrome with immunodeficiency and hypocalcemia in Korea. Our observations suggest that mutation analysis of CHD7 should be performed for patients showing the typical phenotypes of 22q11.2 deletion syndrome but lacking the proven chromosome microdeletion.

• Journal of Genetic Medicine
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• 제18권2호
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• pp.110-116
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• 2021

Microdeletions of chromosome 22q11.2 are one of the most common microdeletions occurring in humans, and is known to be associated with a wide range of highly variable features. These deletions occur within a cluster of low copy repeats (LCRs) in 22q11.2, referred to as LCR22 A-H. DiGeorge (DGS)/velocardiofacial syndrome is the most prevalent form of a 22q11.2 deletions, caused by mainly proximal deletions between LCR22 A and D. As deletions of distal portion to the DGS deleted regions has been extensively studied, the recurrent distal 22q11.2 microdeletions distinct from DGS has been suggested as several clinical entities according to the various in size and position of the deletions on LCRs. We report a case of long-term follow-up of a female diagnosed with a 22q11.2 distal deletion syndrome, identified a deletion of 1.9 Mb at 22q11.21q11.23 (chr22: 21,798,906-23,653,963) using single nucleotide polymorphism array. This region was categorized as distal deletion type of 22q11.2, involving LCR22 D-F. She was born as a preterm, low birth weight to healthy non-consanguineous Korean parents. She showed developmental delay, growth retardation, dysmorphic facial features, and mild skeletal deformities. The patient underwent a growth hormone administration due to growth impairment without catch-up growth. While a height gain was noted, she had become overweight and was subsequently diagnosed with pre-diabetes. Our case could help broaden the genetic and clinical spectrum of 22q11.2 distal deletions.

• Clinical and Experimental Pediatrics
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• 제57권7호
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• pp.333-336
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• 2014

Reports of constitutional ring chromosome 22, r(22) are rare. Individuals with r(22) present similar features as those with the 22q13 deletion syndrome. The instability in the ring chromosome contributes to the development of variable phenotypes. Central nervous system (CNS) atypical teratoid rhabdoid tumors (ATRTs) are rare, highly malignant tumors, primarily occurring in young children below 3 years of age. The majority of ATRT cases display genetic alterations of SMARCB1 (INI1/hSNF5 ), a tumor suppressor gene located on 22q11.2. The coexistence of a CNS ATRT in a child with a r(22) is rare. We present a case of a 4-month-old boy with 46,XY,r(22)(p13q13.3), generalized hypotonia and delayed development. High-resolution microarray analysis revealed a 3.5-Mb deletion at 22q13.31q13.33. At 11 months, the patient had an ATRT ($5.6cm{\times}5.0cm{\times}7.6cm$) in the cerebellar vermis, which was detected in the brain via magnetic resonance imaging.

• 대한유전성대사질환학회지
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• 제14권2호
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• pp.163-167
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• 2014

DiGeorge syndrome is a disorder caused by microdeletion in chromosome 22q11.2 with various abnormalities including cardiac anomaly, facial dysmorphism, thymic and parathyroid hypoplasia, cleft palate and immune dysfunction. The frequency of hypocalcemia caused by hypoparathyroidism is known to be approximately 60% of DiGeorge syndrome. It is known that the disorder mostly occurs in the neonatal period and the symptoms are improved afterwards. Herein we report a case of DiGeorge syndrome only accompanied by hypocalcemia caused by hypoparathyroidism without other abnormalities. She was first diagnosed only at the age of 22 with basal ganglia calcification that had been discovered in brain CT (Computed tomography).

• Clinical and Experimental Pediatrics
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• 제59권sup1호
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• pp.25-28
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• 2016

Phelan-McDermid syndrome is a rare genetic disorder caused by the terminal or interstitial deletion of the chromosome 22q13.3. Patients with this syndrome usually have global developmental delay, hypotonia, and speech delays. Several putative genes such as the SHANK3, RAB, RABL2B, and IB2 are responsible for the neurological features. This study describes the clinical features and outcomes of Korean patients with Phelan-McDermid syndrome. Two patients showing global developmental delay, hypotonia, and speech delay were diagnosed with Phelan-McDermid syndrome via chromosome analysis, fluorescent in situ hybridization, and multiplex ligation-dependent probe amplification analysis. Brain magnetic resonance imaging of Patients 1 and 2 showed delayed myelination and severe communicating hydrocephalus, respectively. Electroencephalography in patient 2 showed high amplitude spike discharges from the left frontotemporoparietal area, but neither patient developed seizures. Kidney ultrasonography of both the patients revealed multicystic kidney disease and pelviectasis, respectively. Patient 2 experienced recurrent respiratory infections, and chest computed tomography findings demonstrated laryngotracheomalacia and bronchial narrowing. He subsequently died because of heart failure after a ventriculoperitoneal shunt operation at 5 months of age. Patient 1, who is currently 20 months old, has been undergoing rehabilitation therapy. However, global developmental delay was noted, as determines using the Korean Infant and Child Development test, the Denver developmental test, and the Bayley developmental test. This report describes the clinical features, outcomes, and molecular genetic characteristics of two Korean patients with Phelan-McDermid syndrome.

• Journal of Genetic Medicine
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• 제4권1호
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• pp.80-83
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• 2007

고리염색체(Ring chromosome)는 매우 낮은 빈도로 발견되는 염색체 이상으로 모든 번호에서 보고되고 있으며 특히 끝곁 매듭 염색체(acrocentric chromosome)에서 빈번하게 관찰 된다. 본 증례는 ring chromosome(고리염색체)11의 산전진단에 관한 것이다. 산모는 36세의 여성으로 모체혈청검사에서 에드워드 증후군의 표시인자가 증가되어, 태아의 염색체 검사를 위해 임신 19.5주에 양수천자술을 시행하였다. 결과는 46,XX,r(11)[65]/45,XX,-11[16]/46,XX[34]로 고리염색체(ring chromosome) 11이 mosaic으로 관찰되었다. 혈액을 이용한 부모 염색체 검사는 모두 정상이었다. 임신 20주에 실시된 정밀초음파 검사에서는 자궁내성장장애(IUGR) 소견을 보였다. 모자익시즘의 확인을 위해 임신 22주에 재대 혈액을 이용한 두번째 염색체 검사 결과는 46,XX,r(11)(p15.5q24.2)[229]/45,XX,-11 [15]이었으며 첫번째 검사에서 관찰되지 않았던 다양한 형태의 고리염색체(ring chromosome)가 소수의 세포에서 관찰되었다. 고리염색체(ring chromosome)11에 대한 FISH 검사에서는 11 염색체의 장완과 11 염색체의 단완의 subtelomeric 부위가 결실되어 있었다.

• Clinical and Experimental Pediatrics
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• 제58권3호
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• pp.108-111
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• 2015

DiGeorge syndrome is an immunodeficient disease associated with abnormal development of 3rd and 4th pharyngeal pouches. As a hemizygous deletion of chromosome 22q11.2 occurs, various clinical phenotypes are shown with a broad spectrum. Conotruncal cardiac anomalies, hypoplastic thymus, and hypocalcemia are the classic triad of DiGeorge syndrome. As this syndrome is characterized by hypoplastic or aplastic thymus, there are missing thymic shadow on their plain chest x-ray. Immunodeficient patients are traditionally known to be at an increased risk for malignancy, especially lymphoma. We experienced a 7-year-old DiGeorge syndrome patient with mediastinal mass shadow on her plain chest x-ray. She visited Severance Children's Hospital hospital with recurrent pneumonia, and throughout her repeated chest x-ray, there was a mass like shadow on anterior mediastinal area. We did full evaluation including chest computed tomography, chest ultrasonography, and chest magnetic resonance imaging. To rule out malignancy, video assisted thoracoscopic surgery was done. Final diagnosis of the mass which was thought to be malignancy, was lymphoproliferative lesion.