De novo supernumerary ring chromosome 7: first report of a non-mosaic patient and review of the literature

The present authors report the case of a 12-year-old-boy with a de novo, non-mosaic supernumerary ring chromosome 7 associated with significant developmental delay and speech difficulty. A review of the literature identified a total of 18 cases with ring chromosomes 7 who can be classified into two groups: (1) patients with a cell line that has 47 chromosomes with a small supernumerary ring chromosome 7 resulting in partial trisomy; and (2) individuals had a cell line with a large ring chromosome replacing one of the normal chromosomes 7 resulting in partial monosomy. A comparison of clinical features in the two groups of patients showed several common features such as growth and mental retardation, and facial dysmorphism, including, ear and eye anomalies. However, patients with partial trisomy have speech difficulty as a distinguishing feature, while patients with partial monosomy have skin lesions as a cardinal feature. All the published cases of ring chromosome 7, irrespective whether they are supernumerary or normal modal number, are mosaics except for one. The present subject is the first case of a de novo, non-mosaic supernumerary ring chromosome 7.     

Ring syndrome caused by ring chromosome 7 without loss of subtelomeric sequences

Ring chromosome 7 is an unusual chromosome anomaly. Here we describe a patient with ring chromosome 7 and we show that both subtelomeres are still present. The diagnosis agrees with 'ring syndrome'. This report helps to further delineate the clinical manifestations of 'ring syndrome' and to distinguish the phenotypic consequences of the presence of a ring chromosome 7 from the phenotypic consequences of terminal chromosome 7 submicroscopic deletions.     

Interstitial deletion of chromosome 7: A case report and review of the literature

A de novo deletion 7q11 leads to q21.2 was identified in a newborn with genital and other minor clinical abnormalities and some degree of psychomotor retardation. A review of the literature revealed a number of cases of deletion 7q, which can be categorized into three groups according to their breakpoints. Attempts to correlate phenotype with genotype in these cases have been only moderately successful, and as yet only deletion 7q32 leads to qter can be associated with a definite clinical syndrome, although a tentative syndrome may be postulated in association with deletion of region 7q22 leads to 7q31.     

Severe anomalies associated with ring chromosome 7

A newborn infant with the polyasplenia sequence, intrauterine growth retardation, cutaneous nevi, and minor anomalies was found to have mosaicism for ring chromosome 7. This patient's anomalies are markedly different from those of previous patients reported with this cytogenetic anomaly.     

Sub-band deletion of 7q36.3 in a patient with ring chromosome 7: Association with holoprosencephaly

We report on a patient with ring chromosome 7 analyzed by both high-resolution mid-prophase G-banding and fluorescence in situ hybridization (FISH) resolving a sub-band deletion of 7q36.3 associated with the clinical manifestation of holoprosencephaly (HPE). © 1996 Wiley-Liss, Inc.     

Discordant phenotypes in a mother and daughter with mosaic supernumerary ring chromosome 19 explained by a de novo 7q36.2 deletion and 7p22.1 duplication

We report on a patient with severe intellectual disability, microcephaly, short stature, and dysmorphic features who, based on standard karyotyping, has two cytogenetic abnormalities: an apparently balanced paracentric inversion of chromosome 7, inv(7)(q31.2q36), and a small supernumerary ring chromosome derived entirely of material from chromosome 19. While the inversion was detected in all cells, mosaicism was observed for the ring chromosome. Interestingly, apparently identical cytogenetic abnormalities were detected in the patient's mother, who presented with normal stature, few dysmorphic features, and normal cognition without microcephaly. While the level of mosaicism could not adequately explain the phenotypic discordance, comparative genome hybridization revealed a de novo terminal deletion of chromosome 7, del(7)(q36.2), and a terminal duplication of chromosome 7, dup(7)(p22.1) in the patient. Additional cytogenetic investigation revealed that the patient inherited a recombinant chromosome derived from a cryptic maternal pericentric inversion: inv(7)(p22q36). The patient's distinctive features are consistent with the wide phenotypic spectrum reported in 7p duplication and 7q terminal deletion syndromes. These chromosomal regions contain several candidate genes of clinical significance, including SHH, EN2, and FAM20C. Our findings strongly suggest that our patient's phenotype is largely attributable to partial 7pter trisomy and partial 7qter monosomy rather than mosaic supernumerary ring chromosome 19.     

Dandy-Walker综合征与7号染色体微缺失

目的 应用微阵列比较基因组杂交技术探讨Dandy-Walker综合征的遗传学病因.方法 选取8例经产前超声检查提示发生Dandy-Walker畸形且常规G显带染色体核型分析未发现异常的胎儿病例,按照标准的Affymetrix cytogenetic 2.7 M微阵列芯片的操作手册进行杂交、洗涤及全基因组扫描,并应用相应的计算机软件分析结果.结果 微阵列比较基因组杂交技术检测提示3例Dandy-Walker畸形胎儿的染色体7p21.3区DNA拷贝数发生了缺失或重复,异常片段中包含与脊髓小脑疾病相关的NDUFA4和PHF14基因.结论 染色体7p21.3区DNA拷贝数的异常改变是Dandy-Walker综合征的病因之一,其发病机制可能与NDUFA4和PHF14基因的表达异常有关.     

The interstitial deletion of bands q33–35 of long arm of chromosome 7: a review with a new case report

Interstitial or terminal deletion resulting in partial monosomy of various segments of the long arm of chromosome 7 was first recorded over two decades ago. Since then, a number of reports have correlated the severity of clinical manifestations with the length of the deletion involved. However, difficulty remains in defining a so-called "distinct syndrome". We present a new case with the shortest interstitial deletion of the long arm of chromosome 7 bands q33-35, i.e. 46,XX,del(7)(pter----q33::q35----qter). A 4-year-old black female was referred for cytogenetic evaluation due to neurodevelopmental delay. Pertinent physical examination at birth was cleft lip and cleft palate which required corrective surgery. At 2 years of age, a myringotomy tube was inserted for repeated ear infection and a hearing aid was required for conductive deafness. Neurological examination revealed poor eye contact, and severe mental and motor retardation. We reviewed 21 cases of a partial interstitial deletion of varied segments of the long arm of chromosome 7, but we were unable to establish a definite relationship with the deletion of various 7q segments with any specific clinical manifestations.     

Familial occurrence of chromosome 7/12 translocation

A new balanced autosomal translocation, t(7;12) (p12;p13), was found in a high genetic risk family in which the mother is a translocation carrier. She had 12 pregnancies, six of which were terminated during the first trimester by spontaneous abortions. Among the six live births, three children inherited the translocation from their mother and were phenotypically normal. The father and three other children had normal karyotypes.     

Nonrandom gain of chromosome 7 in central neurocytoma: A chromosomal analysis and fluorescence in situ hybridization study

Central neurocytoma is a benign, slow-growing neoplasm with favourable prognosis. Biomolecular analysis has failed to demonstrate significant alterations, and no cytogenetic alterations have been reported. In this study we demonstrate chromosome 7 gain in three of nine neurocytomas (33%). Traditional cytogenetic analysis performed in four of the nine cases identified trisomy 7 as the sole chromosomal abnormality in one case. Interphase cytogenetics utilizing fluorescent in situ hybridization (FISH) on cell suspensions from formalin-fixed paraffin-embedded tumour tissue performed in all nine cases detected trisomy 7 in two more cases and tetrasomy in another. Our results suggest that chromosome 7 gain is a feature of neuroectodermal tumorigenesis, possibly conferring growth advantage on the neoplastic cells. FISH on interphase nuclei is a valuable adjunct in the genetic evaluation of rare central nervous system neoplasms with low baseline proliferative activity.     

Deletion of the short arm of chromosome 20

A de novo deletion of the short arm of chromosome 20--del (20) (p11) or (p11p13)--is described in a child with psychomotor retardation and multiple congenital anomalies.     

7号染色体臂间倒位伴Turner综合征家系分析

目的研究7号染色体臂间倒位的遗传机制.方法患儿及父母作染色体检查,并对患儿的家系进行调查.结果患儿的染色体核型为46,XX,inv(7)(p22q11)/45,X,inv(7)(p22q11),其中46,XX,inv(7)(p2q11),85%,45,X,inv(7)(p22q11),15%.父亲的核型为46,XY,inv(7)(p22q11),母亲的染色体正常,患儿的母亲第1胎为3月自然流产,家系中其他成员均无流产史,母系成员中身材均偏矮小.结论染色体臂间倒位能引起流产和畸胎,应作产前诊断.     

Inverted insertion of chromosome 7q and ectrodactyly

An inverted insertion of a segment 7q22–q34 into 3q21 was found in a mentally normal male infant with ectrodactyly of a hand and the feet. A putative gene for ectrodactyly seems to be assigned at 7q22. © 1993 Wiley-Liss, Inc.     

Interstitial deletion of the short arm of chromosome 7 without craniosynostosis

Two female infants with apparently identical interstitial deletions at bands p13 to p15 of chromosome 7 are presented. They differ in phenotype. The first infant has failure to thrive, retardation in development, normal head circumference with ridged metopic suture, blepharophimosis, epicanthal folds, mild hypotelorism, small low-set ears, and a bifid right toe. The second infant has a normal weight, length, and head circumference, blepharophimosis, epicanthal folds, widely spaced nipples, enlarged clitoris, and very large hands and feet. The two patients' clinical and karyotypic findings are compared with previous reports of structural abnormalities of the short arm of chromosome 7. Of the three cases in the literature, craniosynostosis was present in the two patients with deletion of band 7p22, but was not present in the current reports or in another patient with deletion of band 7p14. Our observations, thus, suggest that deletion of bands 7p13 to 7p15, in contrast to more distal deletions at band 7p2, is not associated with craniosynostosis.     

A further case of monosomy 10qter

A child with a terminal deletion of chromosome 10 (q26) is described. A comparison of the phenotypic and cytogenetic features is made in the five reported cases of monosomy 10qter. No phenotypic features are found sufficiently characteristic to delineate a syndrome. Enzymatic activities for PGAMA and GOT1 were normal.     

A case of ring chromosome.

A girl with a G22 ring chromosome is described. There are few physical abnormalities, performance quotient is in the low normal range but verbal skills are much retarded.     

Interstitial deletion of the long arm of chromosome 6 [del(6)(q16q22)]: case report and review of the literature

Partial monosomy of 6q resulting from an interstitial deletion of bands q16----q22 was found in a 12-year-old boy manifesting mental retardation, seizure disorder, and dysmorphic features. The correlation of phenotypic expression and specific long arm deletions of chromosome No. 6 is discussed.     

A complex structural rearrangement of chromosome 4 in a woman without phenotypic features of Wolf-Hirschhorn syndrome

A 32-year-old mentally retarded woman was found to have a complex rearrangement of one chromosome 4. Her karyotype is interpreted as 46,XX,inv(4) (pter----p14::q12----p14::q12----qter) del (4) (pter----15.33::p15.2----qter). Clinically she does not show the features of the Wolf-Hirschhorn syndrome. Her phenotype and cytogenetic findings are compared with 2 other reported cases of 4p-without Wolf-Hirschhorn syndrome.