Chromosome 7q22-q31 duplication: Report of a new case and review

Pure Interstitial 7q21.3-q 31.1 Duplication: A Rare Segmental Genomic Aneuploidy: Case Report and Review of Cases with Distal and Similar Segment Involved

In children with developmental delay (DD) and neurologic impairment, diagnosis can be challenging because of the wide spectrum of causes. Since the last decade, the use of array comparative genomic hybridization (CGH) offered a great contribution to get a diagnosis in complex phenotypes. The chromosome 7 is subject of interest in medical genetics because of its frequent association with chromosome aberrations, rearrangements, and deletions involving clinical manifestations. We hereby reported a 3-year-old male child patient with severe neuro-DD, craniofacial dysmorphisms, and pulmonary stenosis, whose array CGH analysis disclosed a duplication of 14.4 Mb on chromosome 7 (7q21.3-7q31.1). By reviewing the current literature to date, we first reported on neurologic and dysmorphic anomalies related to this rearrangement which was not previously reported.

4q27 deletion and 7q36.1 microduplication in a patient with multiple malformations and hearing loss: a case report

BACKGROUND

Chromosome deletions of the long arm of chromosome 4 in 4q syndrome are characterized by mild facial and digital dysmorphism, developmental delay, growth retardation, and skeletal and cardiac anomalies, which is regarded as an autism spectrum disorder. Moreover, some scarce reports indicate that patients with 4q interstitial deletion and 7p duplication may present symptoms associated with hearing loss.

CASE PRESENTATION

A boy with a severe developmental delay not only post-natal but also intrauterine and several dysmorphic features including microcephaly, ocular hypertelorism, exophthalmos, low-set ears, single palmar flexion crease, and overlapping toes presented discontinued cyanosis and recurrent respiratory infections. MRI, BAEP, echocardiogram and bronchoscopy revealed that he had persistent falcine sinus with a thin corpus callosum, left auditory pathway disorder, patent foramen ovale (2 mm), and tracheobronchomalacia with the right superior bronchus arising from the lateral posterior wall of the right main bronchus. Finally, the patient died with severe pneumonia at 10 months. Array CGH revealed a 23.62 Mb deletion at chromosome 4q27, arr [hg19] 4q27-q31.21 (121, 148, 089-144, 769, 263) × 1, and a 0.85 Mb duplication at chromosome 7q36.1, arr [hg19] 7q36.1-q36.2 (152, 510, 685-153, 363,5 98) × 3. It is rare for 4q syndrome cases or 7q duplications previously reported to have a hearing disorder, pulmonary dysplasia, and pulmonary arterial hypertension.

CONCLUSIONS

The phenotype of our patient mainly reflects the effects of haploinsufficiency of FGF2, SPATA5, NAA15, SMAD1, HHIP genes combined with a microduplication of 7q36.1.

A child with multiple congenital anomalies due to partial trisomy 7q22.1 → qter resulting from a maternally inherited balanced translocation: a case report and review of literature

Background

Parental balanced reciprocal translocations can result in partial aneuploidies in the offspring due to unbalanced meiotic segregation during gametogenesis. Herein, we report the phenotypic and molecular cytogenetic characterization of a 2 years and 4 months old female child with partial trisomy 7q22 → qter. This is the first such reported case resulting from a parental balanced translocation involving the long arms of chromosomes 7 and 14. The phenotype of the proband was compared with that of previously reported cases of trisomy 7q21 → qter or 7q22 → qter resulting from parental balanced translocations.

Case presentation

The proband was born pre-term to a 34-year-old mother with a history of two first trimester miscarriages and an early infant death. She was referred at the age of 8 months for genetic evaluation due to prenatal and postnatal growth retardation, developmental delay and multiple congenital anomalies. On clinical evaluation, she had craniofacial dysmorphic features such as scaphocephaly, large anterior fontanelle with open posterior fontanelle, prominent occiput, triangular face, high forehead, hypertelorism, down slanting eyes, flat nasal bridge, small nose, low set ears, micro-retrognathia, high arched palate and short neck. Cranial computerized tomography scan showed lateral ventriculomegaly with features of early cerebral atrophy. Conventional cytogenetic analysis showed the karyotype 46,XX,der(14)t(7;14)(q22;q32)mat in the proband due to an unbalanced segregation of a maternal balanced translocation t(7;14)(q22;q32). Fluorescence in-situ hybridization analysis confirmed the partial trisomy 7q22 → qter in the proband with a minimal loss of genetic material on chromosome 14. Single nucleotide polymorphism array further confirmed the duplication on chromosome 7q22.1 → qter and a small terminal deletion on chromosome 14q32.3 → qter.

Conclusion

We report the longest-surviving child with trisomy 7q22 → qter due to a parental balanced translocation between chromosomes 7 and 14. Clinical features observed in the proband were consistent with the consensus phenotype of partial trisomy 7q22 → qter reported in the scientific literature. Early diagnosis of these patients using molecular cytogenetic techniques is important for establishing the precise diagnosis and for making decisions pertaining to the prognostication and management of affected individuals.

Electronic supplementary material

The online version of this article (10.1186/s12920-018-0366-6) contains supplementary material, which is available to authorized users.

Deletion 21q22.3 and duplication 7q35q36.3 in a Colombian girl: a case report

BACKGROUND

Genetic disorders are a major cause in the etiology of cases with intellectual disability; however, analysis by a conventional technique such as cytogenetic karyotyping only allows the detection of chromosomal alterations in approximately 9.5 % of cases. The inclusion of new technologies such as high resolution microarray analysis has allowed the study of alterations in chromosomal segments that are less than 5 Mb in length; this has led to an increase in the diagnosis of these patients of up to 25 %.

CASE PRESENTATION

We report the first case of an 8-year-old Colombian girl of mixed race ancestry (Mestizo), with clinical features that include: delayed psychomotor and language development, intellectual disability, upward slanting palpebral fissures, divergent strabismus, low-set and rotated ears, tall and broad nasal bridge, flat philtrum, bifid uvula, posterior cleft palate, increased anteroposterior diameter of her chest, congenital heart defect type interventricular communication, scoliosis, and umbilical hernia. Genetic analysis was performed using comparative genomic hybridization array, which evidenced the deletion of a region of approximately 3.608 Mb on chromosome 21q22.3, and a duplication of 12.326 Mb on chromosome 7q35q36.3, these alterations affect approximately 112 and 186 genes, respectively.

CONCLUSIONS

To date, this is the first report of an associated terminal deletion of 21q and 7q duplication in a patient with delayed psychomotor development and intellectual disability. We consider that future implementation of exome and RNA sequencing techniques, and analysis of their proteomic expression in a clinical context could lead to better analysis and interpretation of the genotype-phenotype correlation in cases similar to that described.

A new case of pure partial 7q duplication

We report on an 18-month-old boy conceived by assisted reproduction technology with developmental delay, hypotonia, microcephaly, frontal bossing, a mild convergent squint, malformed ears, and a short neck. Karyotype analysis revealed a de novo 7q21.1q22.3 duplication characterized by array comparative genomic hybridization (array-CGH) as a segment of 18.69 Mb. Duplications of the long arm of chromosome 7 are uncommon. There are 18 reported cases of different 7q segments with a pure duplication with no additional deletion of other chromosomes. As a consequence, duplications of chromosome 7q have been classified in 4 groups on the basis of the involved region. The present case is included in group 3 which involves interstitial duplications of different sizes. In the literature, only one case with an apparently smaller duplication of the same region has been described. Despite this, the phenotype is different. Moreover, the 2 patients share some phenotypic features, such as psychomotor delay, hypotonia, frontal bossing, short neck, and strabismus. However, the absence of physical characterization in most of the reported cases could justify the lacking phenotype-genotype correlation in patients with partial 7q duplication. Further studies using recent molecular approaches such as array-CGH might permit a more clinically useful grouping of 7q duplications.

Duplication/deletion mosaicism of the 7q(21.1 --> 31.3) region

Mosaicism for structural aberrations is a rare event and the coexistence of a cell line with a duplication and another with a deletion of the same chromosome segment is even more infrequent. We report a boy with a 46,XY,del(7q)/46,XY,dup(7q) mosaicism. High-resolution cytogenetic analysis and fluorescent in situ hybridization (FISH) performed at birth showed a trisomy for region 7q21.1 to 7q31.3 in 90% of metaphases analyzed and monosomy for the same region in 10% of metaphases. At the age of 12 months, karyotype on peripheral blood and exfoliated urinary epithelial cells was 46,XY,dup(7)(q21.1q31.3) in all cells analyzed. The patient presented malformations and psychomotor retardation. His phenotype is compared with other previously case reports describing patients with an interstitial duplication of 7(q21 or q22 --> q31.3). Due to the absence of a normal cell line, we propose a post-zygotic origin of the abnormality during the first mitotic division and a progressive loss of the deleted cells during pre- and post-natal development by selective pressure. The patient described here emphasizes the possible existence of an undetectable cell line in patients previously diagnosed of pure partial 7q trisomy or monosomy to explain the great clinical variability between reported patients. We also describe the culture of urinary epithelial cells in order to perform cytogenetic analysis as a useful non-invasive method.

Disruption of a novel gene (IMMP2L) by a breakpoint in 7q31 associated with Tourette syndrome

Gilles de la Tourette syndrome (GTS) is a complex neuropsychiatric disorder characterized by multiple motor and phonic tics. We identified a male patient with GTS and other anomalies. It was determined that he carried a de novo duplication of the long arm of chromosome 7 [46,XY,dup(7)(q22.1-q31.1)]. Further molecular analysis revealed that the duplication was inverted. The distal chromosomal breakpoint occurred between the two genetic markers D7S515 and D7S522, which define a region previously shown to be disrupted in a familiar case of GTS. Yeast and bacterial artificial chromosome clones spanning the breakpoints were identified by means of FISH analysis. To further characterize the distal breakpoint for a role in GTS, we performed Southern blot hybridization analysis and identified a 6.5-kb SacI junction fragment in the patient's genomic DNA. The DNA sequence of this fragment revealed two different breaks in 7q31 within a region of approximately 500 kb. IMMP2L, a novel gene coding for the apparent human homologue of the yeast mitochondrial inner membrane peptidase subunit 2, was found to be disrupted by both the breakpoint in the duplicated fragment and the insertion site in 7q31. The cDNA of the human IMMP2L gene was cloned, and analysis of the complete 1,522-bp transcript revealed that it encompassed six exons spanning 860 kb. The possible role of IMMP2L and several other candidate genes within the region of chromosomal rearrangement, including NRCAM, Leu-Rch Rep, and Reelin, is discussed. The 7q31 breakpoint interval has also been implicated in other neuropsychiatric diseases that demonstrate some clinical overlap with GTS, including autism and speech-language disorder.