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.     

A paternally derived inverted duplication of 7q with evidence of a telomeric deletion

We report on a de nova constitutional rearrangement involving the long arm of chromosome 7 in a second trimester fetus with the karyotype of 46,XX, inv dup del (7)(pter-q36::q36-q21.2:) pat. Both a large duplication (q21.2-q36) and a small deletion (within q36) were confirmed by FISH studies. DNA analysis on the family showed that the abnormal chromosome was derived from a single paternal homolog. A mechanism is proposed in light of this finding. The phenotype at autopsy was consistent with reported cases of similar duplications in chromosome 7 in that hydrocephalus, a depressed nasal bridge, low set ears, microretrognathia and a short neck were present. Am. J. Med Genet. 68:76–81, 1997 © 1997 Wiley-Liss, Inc.     

Myeloid malignancies with isolated 7q deletion can be further characterized by their accompanying molecular mutations

Deletions in the long arm of chromosome 7 (del(7q)) are recurrent cytogenetic aberrations in myeloid neoplasms. They occur either isolated or as part of a complex karyotype and are associated with unfavorable prognosis in certain disease entities. We performed detailed cytogenetic analysis, molecular analysis, and array comparative genomic hybridization in a cohort of 81 patients with a variety of myeloid malignancies and del(7q) as sole chromosomal alteration. In 70% (57/81) of patients, we identified a commonly deleted region (size: 18 Mb) involving the genomic region 101 912.442 (7q22.1)‐119 608.824 (7q31.31). Furthermore, in 80 patients, we analyzed 17 genes commonly mutated in myeloid neoplasms and identified high mutation frequencies in ASXL1 34% (27/80), TET2 33% (26/80), RUNX1 25% (20/80), DNMT3A 25% (20/80), while TP53 was rarely affected (5%, 4/80). ASXL1 and TET2 showed similar mutation frequencies across all analyzed entities while RUNX1, CBL, and JAK2 were specifically mutated in patients with acute myeloid leukemia (AML), chronic myelomonocytic leukemia, and myeloproliferative neoplasms, respectively. We detected a significantly higher frequency of RUNX1 (42% vs 13%, P = .0001) and ASXL1 (32% vs 14%, P = .008) mutations in AML patients with del(7q) compared to other AML patients in the Medical Research Council unfavorable risk group (n = 464), indicating a cooperative leukemogenic potential. Our data provide further insight into the pathomechanism of this cytogenetic subgroup.     

Cryptic 7q36.2q36.3 deletion causes multiple congenital eye anomalies and craniofacial dysmorphism

A patient with a de novo cryptic 7q36.2q36.3 deletion presented with multiple congenital eye abnormalities, short stature and craniofacial dysmorphism, in the absence of intellectual disability. This report further delineates the 7q36 microdeletion syndrome. © 2013 Wiley Periodicals, Inc.     

Cebocephaly-holoprosencephaly in a newborn girl with a terminal 7q deletion [46,XX,del(7)(pter→q32:)]

Cytogenetic study of a day-old infant showed a terminal del(7q): 46,XX,del(7)(pter→q32:). This infant had cebocephaly with holoprosencephaly. These clinical findings are atypical for the 7q – syndrome, in which patients usually have growth and mental retardation with few facial abnormalities.     

Case report of rec(7)dup(7q)inv(7)(p22q22) and a review of the recombinants resulting from parental pericentric inversions on any chromosomes

We report a rare case of duplication for 7q22 → 7qter and deletion for 7p22 → 7pter, resulting from a meiotic recombination of a paternal pericentric inversion, inv(7)(p22q22). The newborn boy had the 7q trisomy syndrome. In addition, the diagnosis of chondrodysplasia punctata was made from lumbar and hand X-ray films taken soon after birth. Only two cases of rec(7)dup(7q), both in a single family, have been reported previously. We review 133 offspring with recombinations resulting from pericentric inversions on any chromosomes reported between 1981 and 1995. Of the 133 cases, 110 had a long-arm duplication and short-arm deletion, while only 23 had a short-arm duplication and long-arm deletion. In 85 of the 133 cases, the mother was an inversion carrier (five carriers had two affected offspring), and in 46, the carrier was a father (one carrier had three affected offspring). Kaiser [Hum Genet 1984;68:1–47] reviewed 63 offspring with recombinations derived from a parental pericentric inversion reported between 1972 and 1981. In both surveys, recombinations resulting from pericentric inversions of chromosomes 1, 12, 19, and Y were not found. Am. J. Med. Genet. 73:290–295, 1997. © 1997 Wiley-Liss, Inc.     

De novo 3q/7q translocation and associated interstitial 7q35 deletion

In the present report we describe a severely mentally retarded and dysmorphic female child with a de novo 3q/7q reciprocal translocation and loss of band 7q35. This finding supports the hyothesis that the occurrence of mental retardation and/or congenital malformations in de novo autosomal reciprocal translocation may be due to the loss of a small amount of chromatin material during this chromosomal rearrangement.     

16q21 is critical for 16q deletion syndrome

A 1-year-old girl with an interstitial deletion of the long arm of chromosome 16 is reported. She was characterized by a distinct craniofacial dysmorphism, meningoencephalocele, mild hydrocephalus, short neck, broad great toes and abnormally positioned toes. High resolution GTG and RBG banding analyses revealed a karyotype: 46,XX,del(16) (q13q22) de novo. An analysis of the smallest region of overlap revealed that the critical band region for 16q deletion syndrome is 16q21.     

Familial translocation t(10;14) (q26.1;q32.3): report of three offspring with 10q deletion and 14q duplication

We describe two brothers and a cousin with common clinical features, including mild mental retardation, motor delays, hypotonia with truncal ataxia, esotropia, and mild facial and hand dysmorphia. The initial routine chromosome study failed to detect any abnormality in the proband. Based on a high index of clinical suspicion, high-resolution chromosome studies were performed on the proband's parents. A small reciprocal translocation t(10;14) (q26.1;q32.3) was detected in the father. The breakpoint on the derivative chromosome 14 was further placed telomeric to the immunoglobulin heavy-chain gene cluster at the band q32.33 by fluorescence in situ hybridization. Studies of the proband and two affected paternal cousins revealed that each had inherited the same derivative chromosome 10 from their carrier parents. This unbalanced karyotype resulted from an adjacent-1 segregation of the 10;14 translocation.     

Interstitial deletion of chromosome 5 in a neonate due to maternal insertion,ins(8;5)(p23;q33q35)

We describe an infant girl with an interstitial deletion of chromosome bands 5q33 to 5q35 inherited from a maternal interchromosomal insertion ins(8;5)(p23;q33q35) which was demonstrated by fluorescent in situ hybridization with whole chromosome paints. Physical anomalies included hypertonicity, microcephaly, short neck, apparently low-set ears, micrognathia, camptodactyly, mild rocker bottom feet, and hammer toe. Cardiac anomalies included a large ventricular septal defect, patent ductus arteriosus, pulmonary hypertension and hypoplastic right ventricle. She died at age 3 months. Am. J. Med. Genet. 86:289–293, 1999. © 1999 Wiley-Liss, Inc.     

Two cases of 16q12.1q21 deletions and refinement of the critical region

Interstitial deletions of 16q chromosome including 16q12.1q21 region are very rare, with only three cases reported to date. Main clinical features include dysmorphisms, short stature, microcephaly, eye abnormalities, epilepsy, development delay, intellectual disability, and autism spectrum disorder.We report two independent subjects with 16q12.1q21 deletion syndrome presenting with dysmorphic facial features, developmental delay, strabismus, and aggressive behavior. A minimal region of overlap spanning 1.7 Mb on chromosome 16, including IRX5, GNAO1, and NUDT21 genes was shared among these two cases and those previously reported. This minimal region of overlap suggests the potential pathogenic role of these genes, previously implicated in diseases of the central nervous system.     

De novo 7q36 deletion: Breakpoint analysis and types of holoprosencephaly

We report on a de novo 7q36 deletion in a 3-month-old girl with manifestations of the 7q terminal deletion syndrome. Only minimal findings of holoprosencephaly (HPE) were present since only a partial corpus callosum hypoplasia was seen on a magnetic resonance imaging scan of the brain. Extensive fluorescence in situ hybridization analysis showed that the HPE3 critical gene region, inclusive Sonic hedgehog (SHH), En2 (HOX1), and HTR5A, was deleted. A review of 33 other patients with a de novo terminal 7q deletion and the different types of HPE manifestations within these patients will be presented. Am. J. Med. Genet. 75:153–158, 1998. © 1998 Wiley-Liss, Inc.     

Interstitial deletion of chromosome 4, del(4)(q12q21.1), in a mentally retarded boy with a piebald trait,due to maternal insertion,ins(8;4)

A 17-year-old boy who was diagnosed with “Waardenburg syndrome” showed moderate growth and mental retardation. Chromosome analysis showed an apparent interstitial deletion 4q12q21.1. The mother had a direct insertion of the deleted segment into a chromosome 8. The rearrangement was confirmed to be nonreciprocal and an insertion by in situ hybridization using whole chromosome 4 and 8 painting probes. The mother's karyotype is 46,XX,ins(8;4)(q21.2; q12q21.1); that of the propositus is 46,XY, der(4)ins(8;4)(q21.2;q12q21.1)mat. This is the first report of an inherited proximal 4q deletion. Am. J. Med. Genet. 75:78–81, 1998. © 1998 Wiley-Liss, Inc.     

Reassessment of the 12q15 deletion syndrome critical region

Interstitial deletions of the long arm of chromosome 12 are rare and only few cases have been reported in literature so far, with different phenotypic features related to size and gene content of deleted regions. Five patients reported a 12q15-q21 deletion, sharing a 1.3 Mb small region of overlap (SRO) and presenting with developmental delay, nasal speech and mild dysmorphic features.We identified by microarray analysis a new case of 12q15 deletion. Our patient clinical features allow the refinement of the SRO to CNOT2, KCNMB4, and PTPRB genes, improving genotype-phenotype correlations.     

A case of retinoblastoma, associated with histiocytosis-X and mosaicism of a deleted D-group chromosome (13q14→q31)

A previously unpublished association of retinoblastoma and histiocytosis-X is described in a girl. In addition, chromosome analysis revealed a mosaicism of normal and abnormal mitoses. A deleted D-group chromosome (13q14-q31) was present.     

Delineation of 15q13.3 microdeletions

Masurel‐Paulet A, Andrieux J, Callier P, Cuisset JM, Le Caignec C, Holder M, Thauvin‐Robinet C, Doray B, Flori E, Alex‐Cordier MP, Beri M, Boute O, Delobel B, Dieux A, Vallee L, Jaillard S, Odent S, Isidor B, Beneteau C, Vigneron J, Bilan F, Gilbert‐Dussardier B, Dubourg C, Labalme A, Gautier A, Pernes P, Bidon C, Pinoit JM, Huet F, Mugneret F, Aral B, Jonveaux P, Sanlaville D, Faivre L. Delineation of 15q13.3 microdeletions. The increasing use of array‐comparative genomic hybridization (array‐CGH) to identify copy number variations (CNVs) in patients with developmental delay (DD), mental retardation and/or dysmorphic features has allowed the recent recognition of numerous genomic imbalances, including the 15q13.3 microdeletion. Patients with this microdeletion generally present with relatively consistent breakpoints at BP4 and BP5, which include the CHRNA7 gene. About 100 index cases have been reported since the first publication in 2008. This large number of patients ascertained through highly variable samples has been necessary to describe the full phenotypic spectrum of this microdeletion, ranging from mental retardation with dysmorphic features, epilepsy, neuropsychiatric disturbances with or without cognitive impairment to complete absence of anomalies. Here, we describe a collaborative study reporting a new cohort of 12 index patients and 13 relatives carrying a heterozygous BP4–BP5 microdeletion out of a series of 4625 patients screened by array‐CGH for DD. We confirm the clinical expressivity of the disease as well as the incomplete penetrance in seven families. We showed through a review of the literature that males are more likely to be symptomatic. Sequence analysis of CHRNA7 yielded no data to support the unmasking of recessive variants as a cause of phenotypic variability. We also report the first patient carrying a 15q13.3 homozygous microdeletion inherited from both parents. He had severe epileptic encephalopathy with retinopathy, autistic features and choreoathetosis. Besides the classical ～1.5 Mb BP4–BP5 microdeletion, we also describe three index patients and two relatives with a smaller 500 kb microdeletion, including the CHRNA7 gene.     

Deletion 5q35.3

We report on a 15-month-old boy with a de novo deletion of the terminal band of 5q, macrocephaly, mild retrognathia, anteverted nares with low flat nasal bridge, telecanthus, minor earlobe anomalies, bell-shaped chest, diastasis recti, short fingers, and mild developmental delay. © 1994 Wiley-Liss, Inc.