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Vara A, Smith JL, Hashmi SS, Wagner VF, Gunther K, Rodriguez-Buritica DF. Frequency of Sex Chromosome Involvement in a Large Cohort of Subjects with Two Copy Number Variants. Cytogenet Genome Res 2023; 162:599-608. [PMID: 37231787 DOI: 10.1159/000531096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 05/12/2023] [Indexed: 05/27/2023] Open
Abstract
Copy number variants (CNVs) are a common finding in the clinical setting and contribute to both genetic variation and disease. Studies have described the accumulation of multiple CNVs as a disease-modifying mechanism. While it has been described how additional CNVs may play a role in phenotype, in which ways and to what extent sex chromosomes are involved in dual CNV scenario has not been fully defined. To describe the distribution of CNVs, a secondary data analysis using the DECIPHER database on 2,273 de-identified individuals with two CNVs was performed. CNVs were designated larger and secondary based on size and characteristics. We found that the X chromosome was observed to be the most common chromosome involved in secondary CNVs. Further analysis showed CNVs on the sex chromosome have significant differences compared to autosomes when comparing median size (p = 0.013), pathogenicity groups (p < 0.001), and variant classification (p = 0.001). Lastly, we identified chromosome combinations for larger and secondary CNVs and observed the plurality of secondary CNVs fell in the same chromosome as the larger. The observations of this study provide additional information on sex chromosome CNV involvement in a variety of indications.
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Affiliation(s)
- Autumn Vara
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, Texas, USA
- Department of Clinical Cancer Genetics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Janice L Smith
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - S Shahrukh Hashmi
- Division of Medical Genetic, Department of Pediatrics, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth Houston) and Children's Memorial Hermann Hospital, Houston, Texas, USA
| | - Victoria F Wagner
- Division of Medical Genetic, Department of Pediatrics, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth Houston) and Children's Memorial Hermann Hospital, Houston, Texas, USA
- Clinical Operations, Color Health Inc., Burlingame, California, USA
| | - Kathryn Gunther
- Division of Medical Genetic, Department of Pediatrics, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth Houston) and Children's Memorial Hermann Hospital, Houston, Texas, USA
| | - David F Rodriguez-Buritica
- Division of Medical Genetic, Department of Pediatrics, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth Houston) and Children's Memorial Hermann Hospital, Houston, Texas, USA
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Hara-Isono K, Nakamura A, Fuke T, Inoue T, Kawashima S, Matsubara K, Sano S, Yamazawa K, Fukami M, Ogata T, Kagami M. Pathogenic Copy Number and Sequence Variants in Children Born SGA With Short Stature Without Imprinting Disorders. J Clin Endocrinol Metab 2022; 107:e3121-e3133. [PMID: 35583390 DOI: 10.1210/clinem/dgac319] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Indexed: 11/19/2022]
Abstract
CONTEXT Children born small-for-gestational-age with short stature (SGA-SS) is associated with (epi)genetic defects, including imprinting disorders (IDs), pathogenic copy number variants (PCNVs), and pathogenic variants of genes involved in growth. However, comprehensive studies evaluating these 3 factors are very limited. OBJECTIVE To clarify the contribution of PCNVs and candidate pathogenic variants to SGA-SS. DESIGN Comprehensive molecular analyses consisting of methylation analysis, copy number analysis, and multigene sequencing. METHODS We enrolled 140 patients referred to us for genetic testing for SGA-SS. Among them, we excluded 42 patients meeting Netchine-Harbison clinical scoring system criteria for Silver-Russell syndrome and 4 patients with abnormal methylation levels of the IDs-related differentially methylated regions. Consequently, we conducted copy number analysis and multigene sequencing for 86 SGA-SS patients with sufficient sample volume. We also evaluated clinical phenotypes of patients with PCNVs or candidate pathogenic variants. RESULTS We identified 8 (9.3%) and 11 (12.8%) patients with PCNVs and candidate pathogenic variants, respectively. According to the American College of Medical Genetics standards and guidelines, 5 variants were classified as pathogenic and the remaining 6 variants were classified as variants of unknown significance. Genetic diagnosis was made in 12 patients. All patients with PCNVs or candidate pathogenic variants did not correspond perfectly to characteristic clinical features of each specific genetic cause. CONCLUSION We clarified the contribution of PCNVs and pathogenic variants to SGA-SS without IDs. Comprehensive molecular analyses, including copy number analysis and multigene sequencing, should be considered for patients with unknown SGA-SS etiology.
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Affiliation(s)
- Kaori Hara-Isono
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
- Department of Pediatrics, Keio University School of Medicine, Tokyo 160-8582, Japan
| | - Akie Nakamura
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
- Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo 060-8648, Japan
| | - Tomoko Fuke
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
| | - Takanobu Inoue
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
| | - Sayaka Kawashima
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
| | - Keiko Matsubara
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
| | - Shinichiro Sano
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
- Department of Endocrinology and Metabolism, Shizuoka Children's Hospital, Shizuoka 420-8660, Japan
| | - Kazuki Yamazawa
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
- Medical Genetics Center, National Hospital Organization Tokyo Medical Center, Tokyo 152-8902, Japan
| | - Maki Fukami
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
| | - Tsutomu Ogata
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
- Department of Pediatrics, Hamamatsu Medical Center, Hamamatsu 432-8580, Japan
| | - Masayo Kagami
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
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Czakó M, Till Á, Zima J, Zsigmond A, Szabó A, Maász A, Melegh B, Hadzsiev K. Xp11.2 Duplication in Females: Unique Features of a Rare Copy Number Variation. Front Genet 2021; 12:635458. [PMID: 33936165 PMCID: PMC8080037 DOI: 10.3389/fgene.2021.635458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 03/22/2021] [Indexed: 11/13/2022] Open
Abstract
Among the diseases with X-linked inheritance and intellectual disability, duplication of the Xp11.23p11.22 region is indeed a rare phenomenon, with less than 90 cases known in the literature. Most of them have been recognized with the routine application of array techniques, as these copy number variations (CNVs) are highly variable in size, occurring in recurrent and non-recurrent forms. Its pathogenic role is not debated anymore, but the information available about the pathomechanism, especially in affected females, is still very limited. It has been observed that the phenotype in females varies from normal to severe, which does not correlate with the size of the duplication or the genes involved, and which makes it very difficult to give an individual prognosis. Among the patients studied by the authors because of intellectual disability, epilepsy, and minor anomalies, overlapping duplications affecting the Xp11.23p11.22 region were detected in three females. Based on our detailed phenotype analysis, we concluded that Xp11.23p11.22 duplication is a neurodevelopmental disorder.
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Affiliation(s)
- Márta Czakó
- Department of Medical Genetics, Medical School, University of Pécs, Pécs, Hungary.,Szentágothai Research Centre, Pécs, Hungary
| | - Ágnes Till
- Department of Medical Genetics, Medical School, University of Pécs, Pécs, Hungary
| | - Judith Zima
- Department of Medical Genetics, Medical School, University of Pécs, Pécs, Hungary
| | - Anna Zsigmond
- Department of Medical Genetics, Medical School, University of Pécs, Pécs, Hungary
| | - András Szabó
- Department of Medical Genetics, Medical School, University of Pécs, Pécs, Hungary.,Szentágothai Research Centre, Pécs, Hungary
| | - Anita Maász
- Department of Medical Genetics, Medical School, University of Pécs, Pécs, Hungary.,Szentágothai Research Centre, Pécs, Hungary
| | - Béla Melegh
- Department of Medical Genetics, Medical School, University of Pécs, Pécs, Hungary.,Szentágothai Research Centre, Pécs, Hungary
| | - Kinga Hadzsiev
- Department of Medical Genetics, Medical School, University of Pécs, Pécs, Hungary.,Szentágothai Research Centre, Pécs, Hungary
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Kim MK, Seok HH, Kim YS, Chin MU, Sung SR, Lee WS, Shim SH, Yoon TK. Molecular genetic and cytogenetic characterization of a partial Xp duplication and Xq deletion in a patient with premature ovarian failure. Gene 2014; 534:54-9. [DOI: 10.1016/j.gene.2013.10.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 10/04/2013] [Accepted: 10/08/2013] [Indexed: 11/26/2022]
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Sheath KL, Mazzaschi RL, Aftimos S, Gregersen NE, George AM, Love DR. Clinical Outcomes and Counselling Issues regarding Partial Trisomy of Terminal Xp in a Child with Developmental Delay. Sultan Qaboos Univ Med J 2013; 13:311-7. [PMID: 23862040 DOI: 10.12816/0003240] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Revised: 10/15/2012] [Accepted: 11/24/2012] [Indexed: 11/27/2022] Open
Abstract
Female carriers of balanced translocations involving an X chromosome and an autosome offer genetic counselling challenges. This is in view of the number of possible meiotic outcomes, but also due to the impact of X chromosome-localised genes that are no longer subject to gene silencing through the X chromosome inactivation centre. We present a case where delineation of the extent of X chromosome-localised genes on the derivative autosome using molecular karyotyping offers critical information in the context of genetic counselling.
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Wu L, Liu J, Lv W, Wen J, Xia Y, Liang D. An Xp21.3p11.4 duplication observed in a boy with intellectual deficiency and speech delay and his asymptomatic mother. ACTA ACUST UNITED AC 2013; 97:467-70. [PMID: 23828844 DOI: 10.1002/bdra.23118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 01/25/2013] [Accepted: 01/27/2013] [Indexed: 11/10/2022]
Abstract
BACKGROUND Interstitial Xp duplications have been rarely described, especially in males. Male patients show intellectual deficiency (ID) and variable congenital malformations depending on the size and the position of the duplication. METHODS Cytogenetic and molecular analyses using standard G-banding, R-banding, fluorescence in situ hybridization, and an array comparative genomic hybridization analysis for copy number variation detection were performed in the propositus and his mother. RESULTS A 12,168,283 bp interstitial duplication of the Xp21.3p11.4 region was detected in the boy with ID and speech delay and his asymptomatic mother. CONCLUSION An Xp21.3p11.4 duplication was characterized at the molecular level in a boy with ID and speech delay. Genotype-phenotype correlations of interstitial Xp duplications were performed by comparing previously reported cases and our patient.
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Affiliation(s)
- Lingqian Wu
- State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, People's Republic of China
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Chen CP, Su YN, Lin HH, Chern SR, Tsai FJ, Wu PC, Lee CC, Chen YT, Wang W. De novo duplication of Xq22.1→q24 with a disruption of the NXF gene cluster in a mentally retarded woman with short stature and premature ovarian failure. Taiwan J Obstet Gynecol 2012; 50:339-44. [PMID: 22030050 DOI: 10.1016/j.tjog.2011.01.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/19/2010] [Indexed: 11/25/2022] Open
Abstract
OBJECTIVE To present molecular cytogenetic characterization of a de novo duplication of Xq22.1→q24 in a mentally retarded woman with short stature and premature ovarian failure. MATERIALS AND METHODS A 19-year-old woman presented with psychomotor retardation, developmental delay, mental retardation, short stature, low body weight, general muscle hypotonia, distal muscle hypotrophy of the lower extremities, elongated digits, scanty pubic and axillary hair, hypoplastic external female genitalia, and secondary amenorrhea but no clinical features of Pelizaeus-Merzbacher disease. Conventional cytogenetic analysis revealed a karyotype of 46,X,dup(X)(q22.1q24). Fluorescence in situ hybridization determined a direct duplication with a linear tandem orientation. Array comparative genomic hybridization demonstrated partial trisomy Xq [arr cgh Xq22.1q24 (101,490,234-119,070,188 bp)×3] with a 17.6-Mb duplication. RESULTS The duplicated region contained NXF2B, NXF4, NXF3, PLP1, and PGRMC1 genes. There was a disruption of the NXF gene cluster of Xcen-NXF5-NXF2-NXF2B-NXF4-NXF3-Xqter. CONCLUSION A duplication of Xq22.1→q24 with a disruption of the NXF gene cluster in female patients can be associated with clinical manifestations of mental retardation in addition to short stature and premature ovarian failure.
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Affiliation(s)
- Chih-Ping Chen
- Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan.
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Edens AC, Lyons MJ, Duron RM, Dupont BR, Holden KR. Autism in two females with duplications involving Xp11.22-p11.23. Dev Med Child Neurol 2011; 53:463-6. [PMID: 21418194 DOI: 10.1111/j.1469-8749.2010.03909.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We present two phenotypically similar females with Xp duplication who have autism and epilepsy. Case 1 is a 14-year-old Honduran female with autism and medically refractory complex partial, secondarily generalized epilepsy. Case 2 is a 3-year-old Austrian female with autism and medically refractory complex partial epilepsy. Both patients also share features of severe intellectual disability (case 1 has a developmental quotient of 23, case 2 has a developmental quotient of 42) and dysmorphic facial features. Autism was confirmed by thorough clinical evaluations and testing. Case 1 has a karyotype of 46,X,dup(X)(p11.2-p22.33) and a highly skewed X-inactivation pattern (94:6). Brain magnetic resonance imaging (MRI) and electroencephalogram (EEG) were abnormal. Case 2 has a 5-megabase duplication of Xp11.22-p11.23 on chromosome microarray analysis. The patient has a random X-inactivation pattern (77:23). Brain MRI was normal, but EEG was abnormal. Both patients have duplications involving the Xp11.22-p11.23 region, indicating that this is an area of interest for future translational autism research.
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Affiliation(s)
- Anna C Edens
- College of Medicine, Medical University of South Carolina, Charleston, SC, USA.
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9
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DNA methylation analysis of a de novo balanced X;13 translocation in a girl with abnormal phenotype: evidence for functional duplication of the whole short arm of the X chromosome. J Appl Genet 2010; 51:331-5. [PMID: 20720308 DOI: 10.1007/bf03208863] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We report on a 13-month-old girl showing dysmorphic features and a delay in psychomotor development. She was diagnosed with a balanced de novo translocation 46,X,t(X;13)(p11.2;p13) and non-random inactivation of the X chromosome. FISH analysis, employing the X chromosome centromere and XIST-region-specific probes, showed that the XIST locus was not involved in the translocation. Selective inactivation of paternal X, which was involved in translocation, was revealed by the HUMARA assay. The pattern of methylation of 5 genes located within Xp, which are normally silenced on an inactive X chromosome, corresponded to an active (unmethylated) X chromosome. These results revealed that in our proband the X chromosome involved in translocation (Xt) was preferentially inactivated. However, genes located on the translocated Xp did not include XIST. This resulted in functional Xp disomy, which most probably accounts for the abnormal phenotype in our patient.
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Holden ST, Clarkson A, Thomas NS, Abbott K, James MR, Willatt L. A de novo duplication of Xp11.22-p11.4 in a girl with intellectual disability, structural brain anomalies, and preferential inactivation of the normal X chromosome. Am J Med Genet A 2010; 152A:1735-40. [DOI: 10.1002/ajmg.a.33457] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Thorson L, Bryke C, Rice G, Artzer A, Schilz C, Israel J, Huber S, Laffin J, Raca G. Clinical and molecular characterization of overlapping interstitial Xp21-p22 duplications in two unrelated individuals. Am J Med Genet A 2010; 152A:904-15. [DOI: 10.1002/ajmg.a.33340] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Zou YS, Milunsky JM. Developmental disability and hypomelanosis of Ito in a female with 7.3 Mb de novo duplication of Xp11.3-p11.4 and random X inactivation. Am J Med Genet A 2010; 149A:2573-7. [PMID: 19876908 DOI: 10.1002/ajmg.a.33066] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Ying S Zou
- Center for Human Genetics, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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Hunter M, Bruno D, Amor DJ. Functional disomy of proximal Xp causes a distinct phenotype comprising early hypotonia, hypertelorism, small hands and feet, ear abnormalities, myopia and cognitive impairment. Am J Med Genet A 2009; 149A:1763-7. [DOI: 10.1002/ajmg.a.32954] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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14
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Two Patients with X Chromosome Duplication: dupXp and dupXq. Balkan J Med Genet 2009. [DOI: 10.2478/v10034-010-0008-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Two Patients with X Chromosome Duplication: dupXp and dupXqStructural abnormalities of the X chromosome may lead to different phenotypes, depending on the chromosome region affected. We report phenotypic findings of two patients who had X chromosome duplications. One had a menstrual irregularity, a low hairline, cubitus valgus and suffered from dyslexia. The other had multiple congenital anomalies, severe mental-motor retardation and intractable epilepsy. The karyotypes were 46,X,dup(X) (p11.3p21) and 46,X,dup(X)(q13q25) respectively.
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Piccione M, Maresi E, Zollino M, Sanfilippo C, Seminara L, Neri G, Corsello G. Sex reversal from functional disomy of Xp: Prenatal and post-mortem findings. Am J Med Genet A 2008; 146A:2681-7. [DOI: 10.1002/ajmg.a.32514] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Monnot S, Giuliano F, Massol C, Fossoud C, Cossée M, Lambert JC, Karmous-Benailly H. Partial Xp11.23-p11.4 duplication with random X inactivation: clinical report and molecular cytogenetic characterization. Am J Med Genet A 2008; 146A:1325-9. [PMID: 18412111 DOI: 10.1002/ajmg.a.32238] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Partial duplications of the short arm of the X chromosome are relatively rare and have been described in males and females. We describe a 4 10/12-year-old girl presenting with developmental delay, severe language retardation and minor anomalies with slightly elevated head circumference (+1.8 SD), prominent forehead, wide palpebral fissures and anteverted nares. No pigmentary dysplasia of the skin was present. The external genitalia were normal. The karyotype completed by cytogenetic analysis with the Whole Chromosome Painting probe of chromosome X revealed a de novo partial duplication of the short arm of an X chromosome. In order to further characterize the duplicated segment, we used a series of BAC probes extending from band Xp11.22 to Xp22.1. BACs from Xp11.23 to Xp11.4 were duplicated. The karyotype was finally defined as 46,X,dup(X)(p11p11).ish dup(X)(p11.23p11.4)(WCPX+,RP11-416I6++,RP11-386N14++,RP11-466C12++). The X-inactivation status was studied using the human androgen receptor (HUMARA) and the FRAXA locus methylation assay. Unexpectedly, the two X chromosomes were found to be randomly inactivated, in the proband. Indeed, usually, in women with structurally abnormal X chromosome, the abnormal X chromosome is preferentially inactivated and those patients share an apparent normal phenotype. So, we speculate that in the present case, the phenotype of the patient could be explained by a functional disomy of the genes present in the duplicated region. We will discuss the possible implication of these genes on the observed phenotype.
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Affiliation(s)
- Sophie Monnot
- Department of Medical Genetics, Hospital Archet 2, CHU Nice, France.
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Tachdjian G, Aboura A, Benkhalifa M, Creveaux I, Foix-Hélias L, Gadisseux JF, Boespflug-Tanguy O, Mohammed M, Labrune P. De novo interstitial direct duplication of Xq21.1q25 associated with skewed X-inactivation pattern. Am J Med Genet A 2005; 131:273-80. [PMID: 15526291 DOI: 10.1002/ajmg.a.30359] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Genotype-phenotype correlation in women with an abnormal phenotype associated with a duplication of the long arm of the X chromosome remains unclear. We report on prenatal diagnosis and follow-up of a girl with an Xq duplication and dysmorphic features. The abnormal phenotype included growth retardation, hypotonia, and nystagmus. In order to improve the resolution of the cytogenetic analysis, we used both conventional and array-based comparative genomic hybridization to perform a global molecular cytogenetic analysis of the genome. These molecular cytogenetic analyses showed a direct duplication Xq21.1 --> q25 without other chromosomal abnormalities. This duplication was originating from the paternal X chromosome. Moreover, a skewed X-inactivation pattern was observed leading to a partial functional disomy of the chromosomal region Xq21.1q25. This report and review of the literature suggest that functional disomy for chromosome X could explain the abnormal phenotype. In prenatal diagnosis, this can have implication for patient management and genetic counseling.
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Affiliation(s)
- G Tachdjian
- Biologie et Génétique de la Reproduction, AP-HP Hôpital Antoine Béclère, 92140 Clamart, France.
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Kolomietz E, Godbole K, Winsor EJT, Stockley T, Seaward G, Chitayat D. Functional disomy of Xp: Prenatal findings and postnatal outcome. Am J Med Genet A 2005; 134:393-8. [PMID: 15793841 DOI: 10.1002/ajmg.a.30652] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We report on trisomy of the short arm of the X chromosome (Xp11.2 --> pter) due to a de novo unbalanced X;13 translocation diagnosed prenatally in a female fetus. Amniocentesis was performed at 20-weeks' gestation following ultrasound finding of a Dandy-Walker malformation. The trisomy of Xp11.2 --> pter was confirmed with fluorescence in situ hybridization (FISH), using an X chromosome painting probe and telomeric FISH probes specific for the short arm of chromosome X. The karyotype was defined as 46,XX,der(13)t(X;13)(p11.2;p11.2). Molecular analysis suggested that the extra Xp material was of paternal origin. FISH analysis with an XIST probe showed that the derivative chromosome 13 did not include the XIST locus at the X-inactivation center (XIC). A complex phenotype was seen at birth including macrosomia, facial dysmorphism with preauricular tag, congenital heart defects, and structural brain malformations. Because the derivative chromosome was not subject to X inactivation, functional disomy of Xp11.2 --> pter most likely accounts for the abnormal phenotype in this patient.
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Affiliation(s)
- E Kolomietz
- Department of Laboratory Medicine and Pathobiology, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada.
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