Duplication dup(1)(q32q44) detected by comparative genomic hybridization (CGH): further delineation of trisomies 1q

Identifying Genetic Etiology in Patients with Intellectual Disability: An Experience in Public Health Services in Northeastern Brazil

Intellectual disability (ID) is considered a common neuropsychiatric disorder that affects up to 3% of the population. The etiologic origin of ID may be genetic, environmental, and multifactorial. Chromosomopathies are relatively common among the genetic causes of ID, especially in the most severe cases and those associated with dysmorphic features. Currently, the application of new molecular cytogenetics technologies has increasingly allowed the identification of microdeletions, microduplications, and unbalanced translocations as causes of ID. The objective of this study was to investigate the etiology of ID in patients admitted to a public hospital in Northeastern Brazil. In total, 119 patients with ID who had normal karyotypes and fragile X exams participated in this study. The patients were initially physically examined for microdeletion syndromes and then tested using fluorescence in situ hybridization (FISH), multiplex ligation-dependent probe amplification (MLPA), methylation-sensitive polymerase chain reaction (MS-PCR), and chromosome microarray analysis (CMA), according to clinical suspicion. Patients with no diagnoses after FISH, MLPA, and/or MS-PCR evaluations were subsequently tested by CMA. The rate of etiologic diagnoses of ID in the current study was 28%. FISH diagnosed 25 out of 79 tested (31%), MLPA diagnosed 26 out of 79 tested (32%), MS-PCR diagnosed 7 out of 20 tested (35%), and the single nucleotide polymorphism array diagnosed 6 out of 27 tested (22%). Although the CMA is the most complete and recommended tool for the diagnosis of microdeletions, microduplications, and unbalance translocations in patients with ID, FISH, MLPA, and MS-PCR testing can be used as the first tests for specific syndromes, as long as the patients are first physically screened clinically, especially in the public health networks system in Brazil, where resources are scarce.

Developmental Delay and Rehabilitation in an Infant with Partial Trisomy 1q32.1 to 1q44: A Case Report

Partial trisomy 1q is a rare chromosomal disorder characterized by ventriculomegaly with craniofacial, renal, cardiac, and finger and toe anomalies. Most reported cases of partial trisomy1q have involved stillborn or premature deaths due to cardiac or liver failure. This case report describes an 18-month-old patient with partial duplication of the 1q32-44 segments and consequent developmental delays who exhibited improvement in developmental status with rehabilitation. Prenatal ultrasonography and magnetic resonance imaging of the mother revealed ventriculomegaly and atrophic changes in the left cerebral hemisphere of the fetus. The infant was born with micrognathia, microphthalmia, macrocephaly, low-set ears, polydactyly, and long feet at 37+5 weeks of gestation. A chromosomal study revealed an abnormal male karyotype of 46,XY,rec(1)dup(1)(q32.1q44)inv(1)(p36.3q32.1)pat. In this rare case of a patient with partial trisomy, we observed improvement in developmental delays following treatment using appropriate rehabilitation techniques. Further research is required to help validate the findings of this case study and establish a standardized rehabilitation technique that can be subsequently applied to such cases.

Duplication of 1q31.3q41 in two affected siblings due to paternal insertional translocation

We report two sisters with developmental delay and dysmorphic features, as well as a history of seizures. Both sisters have short stature, microcephaly and shared facial dysmorphisms. We detected an 18.1 Mb interstitial gain in 1q31.3q41 and a 140 kb interstitial loss in 7p11.2 in both siblings by using array analysis in the older sister and copy number variation analysis in whole exome sequencing data in the younger sister. We further examined parental chromosomes and found an insertional translocation in the unaffected father, having a 46,XY,ins(7;1)(p11.2;q31.3q41) karyotype. A 1.8 Mb loss at the rearranged 1q segment was subsequently detected on additional array analysis in the father, as well as the 140 kb loss in 7p11.2. We describe the clinical consequences of the 18.1 Mb duplication of the long arm of chromosome 1 due to an unbalanced paternal insertional translocation and compare these with the clinical phenotypes of patients with an overlapping 1q duplication.

Proteinuric glomerulopathy in an adolescent with a distal partial trisomy chromosome 1

We report a case of distal partial trisomy 1 from q32.1 to 41 that have exhibited proteinuric glomerulopathy. The patient was a 17-year-old adolescent with clinical features of low birth weight, mild mental retardation and mild deafness, from the birth. He exhibited non-nephrotic range proteinuria with the mild obesity since the age of sixteen. Image studies did not reveal morphological abnormalities of the kidneys. Renal biopsy findings showed no definitive evidence of primary glomerular diseases, and were characterized by a very low glomerular density, glomerulomegaly and focal effacement of podocyte foot processes. Therapies with dietary sodium restriction, body weight reduction and the administration of angiotensin receptor blocker markedly reduced his proteinuria. It was likely that mismatch between congenital reduction in the nephron number and catch-up growth of the whole body size played a major role in the development of glomerular hyperperfusion injury. At present, the direct contribution of genetic factors due to this chromosomal disorder to such a substantial reduction in the nephron number remains uncertain.

Partial 1q Duplications and Associated Phenotype

Duplications of the long arm of chromosome 1 are rare. Distal duplications are the most common and have been reported as either pure trisomy or unbalanced translocations. The paucity of cases with pure distal 1q duplications has made it difficult to delineate a partial distal trisomy 1q syndrome. Here, we report 2 patients with overlapping 1q duplications detected by G-banding. Array CGH and FISH were performed to characterize the duplicated segments, exclude the involvement of other chromosomes and determine the orientation of the duplication. Patient 1 presents with a mild phenotype and carries a 22.5-Mb 1q41q43 duplication. Patient 2 presents with a pure 1q42.13qter inverted duplication of 21.5 Mb, one of the smallest distal 1q duplications ever described and one of the few cases characterized by array CGH, thus contributing to a better characterization of distal 1q duplication syndrome.

Detailed analysis of 26 cases of 1q partial duplication/triplication syndrome

Partial 1q trisomy syndrome is a rare disorder. Because unbalanced chromosomal translocations often occur with 1q trisomy, it is difficult to determine whether patient symptoms are related to 1q trisomy or other chromosomal abnormalities. The present study evaluated genotype-phenotype correlations of 26 cases diagnosed with 1q partial trisomy syndrome. DNA microarray was used to investigate the duplication/triplication region of 16 cases. Although there was no overlapping region common to all 26 cases, the 1q41-qter region was frequently involved. One case diagnosed as a pure interstitial trisomy of chromosome 1q by G-banded karyotype analysis was instead found to be a pure partial tetrasomy by CytoScan HD Array. In four 1q trisomy syndrome cases involving translocation, the translocated partner chromosome could not be detected by DNA microarray analyzes despite G-banded karyotype analysis, because there were a limited number of probes available for the partner region. DNA microarray and G-banded karyotyping techniques were therefore shown to be compensatory diagnostic tools that should be used by clinicians who suspect chromosomal abnormalities. It is important to continue recruiting affected patients and observe and monitor their symptoms to reveal genotype-phenotype correlations and to fully understand their prognosis and identify causal regions of symptoms.

Involvement of interstitial telomeric sequences in two new cases of mosaicism for autosomal structural rearrangements

Mosaicism for an autosomal structural rearrangement that does not involve ring or marker chromosomes is rare. The mechanisms responsible for genome instability have not always been explained. Several studies have shown that interstitial telomeric sequences (ITSs), involved in some mosaic constitutional anomalies, are potent sources of genomic instability. Here we describe two cases of mosaicism for uncommon constitutional autosomal rearrangements, involving ITSs, identified by karyotyping and characterized by FISH and SNP-array analysis. The first patient, a boy with global developmental delay, had a rare type of pure distal 1q inverted duplication (1q32-qter), attached to the end of the short arm of the same chromosome 1, in approximately 35% of his cells. The second patient, a phenotypically normal man, was diagnosed as having mosaic for a balanced non-reciprocal translocation of the distal segment of 7q (7q33qter), onto the terminal region of the short arm of a whole chromosome 12, in approximately 80% of his cells. The remaining 20% of the cells showed an unbalanced state of the translocation, with only the der(7) chromosome. He was ascertained through his malformed fetus carrying a non-mosaic partial monosomy 7q, identified at prenatal diagnosis. We show that pan-telomeric and subtelomeric sequences were observed at the interstitial junction point of the inv dup(1q) and of the der(12)t(7;12), respectively. The present cases and review of the literature suggest that the presence of ITSs at internal sites of the chromosomes may explain mechanisms of the patients's mosaic structural rearrangements.

Partial trisomy 1q41-qter and partial trisomy 9pter-9q21.32 in a newborn infant: an array CGH analysis and review

We report on a girl who presented with distinctive abducted hip and hyperextended knee. Cytogenetic analysis detected an extra derivative chromosome resulting from a balanced translocation in the mother and 3:1 segregation. Using array comparative genomic hybridization (CGH) in combination with conventional high resolution GTG banding, we designate the karyotype as 47, XX, +der(9)t(1;9)(q41;q21.32)mat, indicating tertiary trisomy of chromosome segments 1q41-qter and 9pter-9q21.32. A review and genotype-phenotype correlation suggested that the patient represented most of the manifestations of duplication of chromosome arms 1q and 9p. To our knowledge, a similar case has so far not been reported.

Duplication of AKT3 as a cause of macrocephaly in duplication 1q43q44

Somatic and germline duplications of AKT3 and activating mutations of this gene have been reported in individuals with megalencephaly and hemimegalencephaly. We report on a patient with macrocephaly and a 3 Mb duplication on 1q43q44 that includes AKT3. This duplication was detected by array comparative genomic hybridization. The patient presented with moderate developmental delays in gross motor movements and speech. She also had macrocephaly, frontal bossing, hypertelorism, wide nasal bridge, small alae nares, short philtrum, prominent upper lip, and low-set, protruding ears. The 3 Mb duplicated region contained 15 genes including AKT3. The observation of megalencephaly in a child with 1q43q44 duplication provides further evidence of involvement of AKT3 dosage imbalances in brain growth disturbance.

Monosomy 3pter-p25.3 and trisomy 1q42.13-qter in a boy with profound growth and developmental restriction, multiple congenital anomalies, and early death

Albeit rare, 3pter-p25 monosomy or 1q42-qter trisomy syndromes have been documented in the literature. Here, we report a unique case with a combination of 3pter-p25 monosomy and 1q42-qter trisomy, delineated by array comparative genomic hybridization analysis. The proband was a newborn male with multiple congenital anomalies that included brain malformation, ocular anomalies, trachea-laryngomalacia, cardiac defects, intestinal malrotation, and cutaneous findings in conjunction with biochemical anomalies, profound growth and developmental restriction, and early death. To our knowledge, this is the first case report of this unique chromosomal imbalance.

Congenital diaphragmatic hernia with a pure duplication of chromosome 1q: report of the first surviving case

Congenital diaphragmatic hernia (CDH) occurs in multiple malformation syndromes and associations, and has been associated with cytogenetic aberrations on almost every chromosome arm. However, CDH with a duplication of chromosome 1q is very rare in the literature, and all previously reported cases with detailed clinical courses died soon after birth. We present the first surviving case of CDH with a duplication of 1q12-q23, who had arthrogryposis multiplex congenita and hypertrophic cardiomyopathy. CDH patients with a proximal duplication of chromosome 1q may have a chance for survival, and CDH with a duplication of chromosome 1q is not necessarily a lethal association.

Distal partial trisomy 1q: report of two cases and a review of the literature

We report on two cases with partial trisomy 1q syndrome. One case was a mid-trimester fetus with multiple malformations that was prenatally diagnosed with a de novo distal partial trisomy 1q. Prenatal ultrasound at 24th gestational week demonstrated the presence of cleft lip and palate, increased biparietal diameter and decreased abdominal circumference. Cytogenetic analysis (GTG banding) and subsequent fluorescence in situ hybridization (FISH) using whole chromosome paint 1 and multicolor banding (MCB) demonstrated an aberrant karyotype 46,XY,dup(1)(q31q43 approximately 44). The second case was a newborn male infant with multiple congenital malformations. He had a derivative chromosome 18 as a result of a maternal insertion involving chromosomes 1 and 18. Further analyses including MCB showed his karyotype as 46,XY,ins(18;1)(q22;q23q31.1 approximately 32). The present cases and a review of the literature suggest that partial trisomy of the long arm of chromosome 1 is a distinct clinical entity.

Duplication dup(1)(q41q44) defined by fluorescence in situ hybridization: delineation of the ‘trisomy 1q42→qter syndrome’

We report on a novel case of pure partial tandem duplication 1q42q43 confirmed by fluorescence in situ hybridization (FISH). We compare the manifestations of our patient with similar cases previously reported. We conclude that the most common clinical manifestations of trisomy 1q42qter are prenatal and postnatal growth retardation, relative macrocephaly, triangular face, prominent forehead, broad nasal bridge, abnormal philtrum, micro/retrognathia, cardiac defects and mental retardation. We would like to emphasize the importance of the FISH technique in the identification of the duplicated segment.

Constitutional partial 1q trisomy mosaicism and Wilms tumor

We report on a female patient with severe-profound mental retardation, multiple congenital anomalies, as well as a history of mosaicism for partial 1q trisomy in the amniotic fluid and a previous Wilms tumor specimen. Peripheral blood and fibroblasts were studied and did not demonstrate the mosaicism initially detected for 1q. Array comparative genomic hybridization yielded negative results. Additional cytogenetic studies helped clarify the previous findings and revealed evidence of partial 1q trisomy mosaicism in normal kidney tissue and in a kidney lesion. GTG-banded results showing low-percentage mosaicism for the structural rearrangement der(1)t(1;1)(p36.1;q23) in both tissues were corroborated by fluorescence in situ hybridization studies. We hypothesize that the partial 1q trisomy predisposed the target tissue (in this case kidney) to neoplasia. This study provides further support for the hypothesis that certain constitutional chromosomal abnormalities can predispose to cancer. As detection of a low-percentage mosaicism may be hampered by the limits imposed by currently available technology and the constraint of a finite sample size, extra vigilance in monitoring other somatic tissues will be needed throughout the patient's lifetime. Anticipatory clinical guidance and prognostication are meaningful only if given accurate cytogenetic diagnoses. To the best of our knowledge, this is the first reported case of Wilms tumor associated with constitutional partial 1q trisomy, either in pure or mosaic form, with the particular 1q23 breakpoint in conjunction with a break on 1p36.1.

Three cases with rare interstitial rearrangements of chromosome 1 characterized by multicolor banding

In this report, we describe three unrelated patients with similar symptoms such as mental retardation, growth delay and multiple phenotypic abnormalities. GTG-banding analysis revealed karyotypes with add(1p) in two cases and an add(1q) in the third. Fluorescence in situ hybridization (FISH) analysis using high resolution multicolor banding (MCB) characterized the aberrations of the abnormal chromosomes 1 as a (sub)terminal duplication and inverted duplications, respectively. Although three different chromosomal regions i.e. 1p36.1, 1p36.2-->1p31.3 and 1q41-->1q44 were involved, all three patients had similar patterns of dysmorphic findings. These cases demonstrate the power of MCB in the characterization of small interstitial chromosomal aberrations and resulted in the characterization of three previously unreported congenital chromosome 1 rearrangements.

Mosaic duplication 1(q11q44) in an infant with nephroblastomatosis and mineralization of extraplacental membranes

Partial trisomy of 1q is rare. Only 32 cases of isolated partial trisomy 1q have been previously reported. From these cases, a characteristic phenotype is beginning to emerge. We present a case of mosaic duplication of 1q [46,XX,dup (1)(q11q44)/46,XX]. Many features of our patient have been described in previous patients, thus supporting the emerging phenotype. Two particular features, however, have not been previously described. The present case demonstrated extensive mineralization of the extraplacental membranes and bilateral nephromegaly, with an extreme form of diffusely hyperplastic perilobar nephroblastomatosis. Clinical comparison is made between our case and previously reported cases, and the clinical significance of the unique findings are reviewed and discussed.

Prenatal diagnosis of trisomy 1q21-qter: Case report and review of literature

We report on a midtrimester fetus with multiple malformations, who was prenatally found to have pure partial trisomy 1q with duplication 1q21-qter. Prenatal ultrasound at 23 gestational weeks demonstrated craniofacial dysmorphism, ventriculomegaly, hand anomalies, and multiple visceral anomalies including cardiac defect, duodenal atresia, omphalocele, and urethral obstruction in the fetus. After pregnancy termination, external morphologic examination confirmed the sonographic characteristics, but autopsy was refused. Cytogenetic analysis (GTG banding) and subtelomeric probes (FISH) demonstrated an aberrant karyotype 46,XY,der(1)(1qter --> 1q21::1p36.3 --> 1qter) in a total of 139 amniotic fluid cells. Trisomy of the long arm of chromosome 1 is a rare condition. Large duplications of almost the entire 1q had so far been described in five mosaic cases. The present case and review of the literature suggest that duplication 1q21-qter is a serious condition with pre- or perinatal demise of all reported cases. This case further delineates the phenotype in trisomy 1q.

Segregation of a t(1;3) translocation in multiple affected family members with both types of adjacent-1 segregants

A subtle balanced translocation involving the terminal regions of 1q and 3p was identified in a large family by high-resolution karyotype analysis and confirmed by fluorescence in situ hybridization (FISH) analysis. In this family, segregation of a balanced t(1:3)(q42.3;p25) chromosome translocation led to two types of viable unbalanced complements. The proband inherited the derivative chromosome 3, resulting in partial trisomy of 1q and partial monosomy of 3p. A paternal uncle and cousin had the reciprocal rearrangement with a derivative of chromosome 1, resulting in partial monosomy for 1q and partial trisomy for 3p. While profound mental and physical retardation and congenital heart defects were characteristics for both rearrangements, facial dysmorphism was quite distinct for each imbalance. Individuals who had the derivative chromosome 3 had a long face, wide eyebrows, small palpebral fissures, hypertelorism, prominent glabella, a large tip of the nose, long philtrum with thin upper lip, and low set-ears. In contrast, family members with the derivative of chromosome 1 had a tall forehead with bifrontal narrowing, full and large cheeks, and large simple ears. Since the translocated segments are small and approximately equal in size in this family, it is not surprising that viability was seen in individuals with both types of adjacent-1 segregation. In this kindred, the ratio of normal to abnormal individuals born to balanced carriers is believed to be about 1:1.5. This suggests that the recurrence risk for carriers is 50%.

Attenuated phenotype in a child with trisomy for 1q due to unbalanced X;1 translocation [46,X,der(X),t(X;1)(q28;q32.1)]

We report a case of an X;1 translocation in a 9-month-old female infant with mild dysmorphic features and developmental delay. High-resolution chromosome analysis revealed a de novo, unbalanced translocation between chromosomes X and 1 [46,X,der(X),t(X;1)(q28;q32.1)]. Breakpoints on the derivative X and the size of the translocated segment have been defined by fluorescence in situ hybridization (FISH) with Xq and 1q specific probes. The rearrangement in this patient results in monosomy for Xq28-qter and trisomy for 1q32.1-qter. Replication studies demonstrated late replication of the derivative X in 80% of the observed cells, with the exception of 20% of the cells where X inactivation failed to spread into the translocated 1q segment. Patients with pure trisomy for the distal segment of 1q present a considerably more severe phenotype compared to that seen in our patient, including facial dysmorphisms, urogenital and cardiac anomalies. We suggest that the absence of many of the characteristic features for trisomy 1q in our patient, may reflect a mosaic pattern of inactivation of the translocated autosomal segment on the derivative X chromosome.

Prenatal detection of mosaic trisomy 1q due to an unbalanced translocation in one fetus of a twin pregnancy following in vitro fertilization: a postzygotic error

Complete or mosaic trisomy for all of chromosome 1q has been seen rarely in a recognized pregnancy. A patient presented with twins following in vitro fertilization (IVF). Ultrasound showed twin A to have a diaphragmatic hernia, thick nuchal fold, and subtle intracranial abnormalities. Twin B appeared normal and a thick dividing membrane was seen. Amniocentesis of twin A showed a male karyotype with mosaic trisomy 1q in 57% of cells resulting from a translocation between chromosomes Yq12 and 1q12. Parental karyotypes were normal. The twins were delivered at 33 weeks. Twin A died at 1 hr of life. Autopsy confirmed the left diaphragmatic hernia and hypoplastic lungs. Autopsy also revealed a partial cleft palate, syndactyly of the second and third toes bilaterally, external deviation of the left 5th toe, and contractures of the index fingers bilaterally. A recent report documented formation of a chimera resulting from embryo amalgamation after IVF. Given the rarity of the cytogenetic findings in our case, we sought to determine if the mosaicism was a result of chimera formation related to the IVF. Thirteen polymorphic loci throughout the genome, in addition to four on 1q and four on 1p, were amplified by PCR. Only two alleles were observed at each of these loci in twin A, one paternal and the other maternal. We present further clinical findings of this case with a rare cytogenetic abnormality that appears to have originated from a postzygotic mitotic error and not embryo amalgamation.