Array-CGH study of partial trisomy 9p without mental retardation

A Systematic Review of Reproductive Counseling in Cases of Parental Constitutional Reciprocal Translocation (9;22) Mimicking BCR-ABL1

We aim to determine the spectrum of cytogenetic abnormalities and outcomes in unbalanced offspring of asymptomatic constitutional balanced t(9;22) carriers through a systematic literature review. We also include a case of a constitutional balanced t(9;22) carrier from our institution. Among the 16 balanced t(9;22) carriers in our review, 13 were maternal and 3 were paternal. Of the 15 unbalanced translocation cases identified, 13 were live births, one was a missed abortion, and one resulted in pregnancy termination. The spectrum of established syndromes reported among the live births was the following: trisomy 9p syndrome (6/13), dual trisomy 9p and DiGeorge syndrome (3/13), dual 9q subtelomere deletion syndrome and DiGeorge syndrome (1/13), 9q subtelomere deletion syndrome (1/13), and DiGeorge syndrome (1/13). One unbalanced case did not have a reported syndrome. The phenotype of the unbalanced cases included cardiac abnormalities (5/13), neurological findings (7/13), intellectual disability (6/10), urogenital anomalies (3/13), respiratory or immune dysfunction (3/13), and facial or skeletal dysmorphias (13/13). Any constitutional balanced reciprocal t(9;22) carrier should be counseled regarding the increased risk of having a child with an unbalanced translocation, the spectrum of possible cytogenetic abnormalities, and predicted clinical phenotype for the unbalanced derivative.

A rare familial rearrangement of chromosomes 9 and 15 associated with intellectual disability: a clinical and molecular study

Background

There are many reports on rearrangements occurring separately in the regions of chromosomes 9p and 15q affected in the case under study. 15q duplication syndrome is caused by the presence of at least one extra maternally derived copy of the Prader–Willi/Angelman critical region. Trisomy 9p is the fourth most frequent chromosome anomaly with a clinically recognizable syndrome often accompanied by intellectual disability. Here we report a new case of a patient with maternally derived unique complex sSMC resulting in partial trisomy of both chromosomes 9 and 15 associated with intellectual disability.

Case presentation

We characterise a supernumerary derivative chromosome 15: 47,XY,+der(15)t(9;15)(p21.2;q13.2), likely resulting from 3:1 malsegregation during maternal gametogenesis. Chromosomal analysis showed that a phenotypically normal mother is a carrier of balanced translocation t(9;15)(p21.1;q13.2). Her 7-year-old son showed signs of intellectual disability and a number of physical abnormalities including bilateral cryptorchidism and congenital megaureter. The child’s magnetic resonance imaging showed changes in brain volume and in structural and functional connectivity revealing phenotypic changes caused by the presence of the extra chromosome material, whereas the mother’s brain MRI was normal. Sequence analyses of the microdissected der(15) chromosome detected two breakpoint regions: HSA9:25,928,021-26,157,441 (9p21.2 band) and HSA15:30,552,104-30,765,905 (15q13.2 band). The breakpoint region on chromosome HSA9 is poor in genetic features with several areas of high homology with the breakpoint region on chromosome 15. The breakpoint region on HSA15 is located in the area of a large segmental duplication.

Conclusions

We discuss the case of these phenotypic and brain MRI features in light of reported signatures for 9p partial trisomy and 15 duplication syndromes and analyze how the genomic characteristics of the found breakpoint regions have contributed to the origin of the derivative chromosome. We recommend MRI for all patients with a developmental delay, especially in cases with identified rearrangements, to accumulate more information on brain phenotypes related to chromosomal syndromes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13039-021-00565-y.

De Novo Duplication of Chromosome 9p in a Female Infant: Phenotype and Genotype Correlation

Trisomy 9p syndrome is the fourth most frequent chromosome aberration seen in infants. Duplication of the critical region 9p22p24 leads to mental retardation, psychomotor delay, and craniofacial and digital anomalies. We report a 2-year-old Ecuadorian girl with Trisomy 9p syndrome. Although her phenotype shares characteristics of Noonan syndrome, Giemsa trypsin banding technique shows there is an extra chromosomal segment on chromosome 14, and array analysis shows that it belongs to a duplication of 38 Mb of 9p13.1p24.3. Fluorescence in situ hybridization analysis detected three signals from 9p chromosome. The duplication is de novo, being another unique case of the few reported in the literature.

Partial trisomy 9 (9pter->9q22.1) and partial monosomy 14 (14pter- >14q11.2) due to paternal translocation t(9;14)(q22.1;q11.2) in a case of Dysmorphic features

Trisomy 9 including mosaic and partial trisomy is less frequently seen chromosomal abnormality in live born children. The pure or partial trisomy 9 frequently been reported in prenatal diagnosis and product of conception. However few studies reported partial trisomy 9 in live born children. In addition data on genotype and phenotype correlation of partial trisomy is not well understood except few case reports. Here we report a case of partial trisomy 9 and monosomy 14 with a 46,XY,der(9)t(9;14)(q22.1;q11.2)pat,-14 karyotype in a 5-year old dysmorphic child. The proband was confirmed as trisomic for 9pter->9q22.1 and monosomic for 14pter->q11.2 due to paternal t(9;14)(q22.1;q11.2) balanced translocation using a combination of conventional and molecular cytogenetic (fluorescence in situ hybridization, array-comparative genomic hybridization) techniques. The clinical features similar to pure trisomy 9 is due to duplication of the large region of chromosome 9. However, the present report of partial trisomy 9 and monosomy 14 is a novel case report and showing comparatively longer survival which have not been previously reported in the literature. The parent of the proband was counseled for the future pregnancies.

Good response to long-term therapy with growth hormone in a patient with 9p trisomy syndrome: A case report and review of the literature

The 9p trisomy syndrome is a rare condition, clinically characterized by a wide range of dysmorphic features, intellectual disability, and, in most patients, by short stature. Recombinant human growth hormone (rhGH) therapy is still controversial in syndromic disorders, the reason for which it is not currently indicated. Here we report a 7-year-old boy with 9p trisomy syndrome and marked short stature. Results of routine laboratory assessments were normal. IGF1 and IGFBP3 levels were both in the normal range (-1.6 and -0.7 SDS, respectively). GH peak in response to oral clonidine stimulation test was 3.5 μg/L, which is considered a normal response. Chromosomal analysis revealed the karyotype 47,XY, + del(9)(pter-q11:) dn. SNP array data indicated absence of mosaicism [arr 9p24.3-p13.1 (203,861-38,787,480) x3]. By the age of 8.3 years, the patient had persistent short stature (-2.9 SDS) with normal growth velocity (4.9 cm/y; -0.7 SDS), not showing spontaneous catch-up. After 5.6 years of rhGH therapy (50 μg/kg/d), height SDS improved from -2.9 to -1.0. This result suggests that rhGH therapy could be considered for patients with 9p trisomy syndrome who present with short stature. The degree of intellectual disability and the potential for social inclusion should be taken into account when recommending this treatment. Additional studies are needed to establish the benefits of height gain in these patients.

Duplication 9p and their implication to phenotype

Background

Trisomy 9p is one of the most common partial trisomies found in newborns. We report the clinical features and cytogenomic findings in five patients with different chromosome rearrangements resulting in complete 9p duplication, three of them involving 9p centromere alterations.

Methods

The rearrangements in the patients were characterized by G-banding, SNP-array and fluorescent in situ hybridization (FISH) with different probes.

Results

Two patients presented de novo dicentric chromosomes: der(9;15)t(9;15)(p11.2;p13) and der(9;21)t(9;21)(p13.1;p13.1). One patient presented two concomitant rearranged chromosomes: a der(12)t(9;12)(q21.13;p13.33) and an psu i(9)(p10) which showed FISH centromeric signal smaller than in the normal chromosome 9. Besides the duplication 9p24.3p13.1, array revealed a 7.3 Mb deletion in 9q13q21.13 in this patient. The break in the psu i(9)(p10) probably occurred in the centromere resulting in a smaller centromere and with part of the 9q translocated to the distal 12p with the deletion 9q occurring during this rearrangement. Two patients, brother and sister, present 9p duplication concomitant to 18p deletion due to an inherited der(18)t(9;18)(p11.2;p11.31)mat.

Conclusions

The patients with trisomy 9p present a well-recognizable phenotype due to facial appearance, although the genotype-phenotype correlation can be difficult due to concomitant partial monosomy of other chromosomes. The chromosome 9 is rich in segmental duplication, especially in pericentromeric region, with high degree of sequence identity to sequences in 15p, 18p and 21p, chromosomes involved in our rearrangements. Thus, we suggest that chromosome 9 is prone to illegitimate recombination, either intrachromosomal or interchromosomal, which predisposes it to rearrangements, frequently involving pericentromeric regions.

Unbalanced translocation involving partial trisomy 9p and partial monosomy yq with neurodevelopmental delays

We present a 4-year-old Honduran boy with mild neurodevelopmental delays, growth delays, dysmorphic features, and small genitalia. Chromosome analysis initially revealed a single X chromosome and a marker chromosome derived from the short arm of chromosome 9 which was consistent with Turner syndrome as only 1 sex chromosome could be identified. However, on further analysis, he was found to have an unbalanced translocation involving the short arm of chromosome 9 and the long arm of the Y chromosome. The translocation resulted in partial trisomy 9p and partial monosomy Yq. The patient's clinical features are felt to be the result of partial trisomy 9p. In addition, partial monosomy Yq is associated with male infertility. Testing of the patient's parents was normal, indicating this was a de novo translocation. Additional evaluations of this child and his parents allowed an accurate assessment of his diagnosis, long-term prognosis, and chance of recurrence.

Another rare case of a child with de novo terminal 9p deletion and co-existing interstitial 9p duplication: clinical findings and molecular cytogenetic study by array-CGH

Trisomy 9p is the fourth most common chromosome abnormality found in liveborns. We report on a rare case of partial trisomy 9p complicated by partial monosomy 9p. Clinical manifestation included craniofacial abnormalities typical for trisomy 9p syndrome, developmental delay, mental retardation and brain anomaly in the form of Dandy-Walker malformation. The cytogenetic abnormality was investigated with FISH and array-CGH to characterize the breakpoints of the complex rearrangement. The patient's karyotype was 46,XX,der(9)del(9)(p24)dup(9)(p21p24)dn.arr 9p24.3p24.2 (1-2,414,485)×1,9p24.2p21.3(2,414,485-24,101,280)×3. The cytogenetic rearrangement led to a 2.4-Mb deletion of 9p24.2pter and a 21.6-Mb duplication of 9p24.2p21.3. The clinical and cytogenetic findings in our and other similar patients are compared.