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![Cytogenetics results. A) Partial G-banding karyotype of proband (III-1): 45,XX,der(10)t(10;15)(q26.3;q11.2),-15 [red ovale]; B) Ideogram showing normal chromosomes 10 and 15, as well as derivative chromosome 10 of proband (III-1); C) FISH analysis of proband (III-1): ish del(15)(q11.2q11.2)(SNRPN-, PMLx2) [SNRP/red, PML/green]; D) Partial G-banding karyotype of the proband’s mother (II-2): 46,XX,t(10;15)(q26.3;q11.2) [red ovale]; E) Ideogram showing chromosomes 10, 15 and the balanced reciprocal translocation in the proband’s mother (II-2).](profile/Adriana-Ruiz-Herrera/publication/275240183/figure/fig5/AS:267892444889160@1440881944939/Cytogenetics-results-A-Partial-G-banding-karyotype-of-proband-III-1.png)
Cytogenetics results. A) Partial G-banding karyotype of proband (III-1): 45,XX,der(10)t(10;15)(q26.3;q11.2),-15 [red ovale]; B) Ideogram showing normal chromosomes 10 and 15, as well as derivative chromosome 10 of proband (III-1); C) FISH analysis of proband (III-1): ish del(15)(q11.2q11.2)(SNRPN-, PMLx2) [SNRP/red, PML/green]; D) Partial G-banding karyotype of the proband’s mother (II-2): 46,XX,t(10;15)(q26.3;q11.2) [red ovale]; E) Ideogram showing chromosomes 10, 15 and the balanced reciprocal translocation in the proband’s mother (II-2).
Source publication
The 15q11q13 region is subject to imprinting and is involved in various structural rearrangements. Less than 1% of Angelman Syndrome patients are due to translocations involving 15q11q13. These translocations can arise de novo or result from the segregation of chromosomes involved in a familial balanced translocation.
A 5-year-old Mexican girl pres...
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Angelman syndrome (AS) is a neurodevelopmental disorder caused by deletion of the maternally inherited 15q11q13 region, paternal uniparental disomy 15 [upd(15)pat], an imprinting defect of the maternal chromosome region 15q11q13, or a pathogenic mutation of the maternal UBE3A allele. Predisposing factors for upd(15)pat, such as nonhomologous robert...
Angelman syndrome (AS) is a distinct condition that presents with severe developmental delay. This condition also presents with speech impairment, ataxia/tremor, and inappropriate laughter. Some other features in most patients include microcephaly, seizures, tongue protrusion, wide mouth, and hypopigmentation. This case aims to emphasize the value...
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Background
Small supernumerary marker chromosomes (sSMCs) are common structurally abnormal chromosomes that occur in 0.288% of cases of mental retardation. Isodicentric 15 (idic(15)) is common in sSMCs and usually leads to a rare chromosome disorder with distinctive clinical phenotypes, including early central hypotonia, developmental delay, epilep...
Citations
... However, clinical genetic testing is often done before testing patients using the FISH method due to cost and ease. (Bailus and Segal, 2014;Halder et al.,2015;Yokoyama et al., 2015). ...
... Currently, AS symptoms are managed by drug therapy to treat gastrointestinal disorders, seizures, and hyperactivity; concomitantly, the patient undergoes occupational, physical, and speech therapy for developmental delay, ataxia, and improving nonverbal communication modalities (Williams et al., 2010). The reasoning behind nonverbal communication is that most patients have a minimal number of words they are able to use to communicate (Yokoyama et al., 2015). Furthermore, some researchers have primarily characterized AS by the characteristic lack of speech seen in patients (Germain, 2014). ...
Neurodevelopmental disorders limit the mental, physical, and social lives of affected individuals and their families. These disorders are often related to genetic abnormalities having a distinct chromosomal location. The abnormalities can cause incorrect proteins to be formed or biochemical pathways to be blocked, predominately affecting brain development, but also having pleiotropic effects. Research into defining and correcting these genetic abnormalities is important to help distinguish between unique neurodevelopmental disorders so that proper clinical interventions are available for affected individuals. In the following review, Angelman syndrome, which results from UBE3A gene function being lost at maternal chromosome 15q11.2-q13, will be discussed. Angelman patients suffer from the defining characteristics of speech impairment, uncontrolled laughing and smiling, motor development issues, muscle tension, and possible ataxia. The genetic mechanisms of the disorder as well as possible therapies will be discussed, with future areas of research into genetic therapies to treat Angelman syndrome also put forth. Research into Angelman syndrome can provide an avenue for a clearer understanding of other neurodevelopmental disorders.
Angelman syndrome (AS; OMIM 105830) is a congenital neurodevelopmental disorder typically caused by maternal chromosome 15q11.2-q13 deletion, Ubiquitin-protein ligase E3A (UBE3A) gene mutations, paternal uniparental disomy (UPD), or imprinting center mutations. The rate of sporadic Angelman syndrome carrying UPD is known to be 2-3%. Paternal UPD has been detected in approximately 2-3% of AS patients. Many reports have suggested that patients with UPD-associated AS cases are heterodisomic. We reported a case of a 4-year-old patient diagnosed with AS. She presented with dysmorphic features, including a wide mouth with protruding tongue, flexion of both fingers, drooling with mental retardation, absence of speech, disrupted sleep, without self-injuring behavior. Although electroencephalogram (EEG) findings are important to diagnosing AS, specific EEG and also magnetic resonance imaging (MRI) findings were not detected in our case. In the diagnostic process, which began with conventional cytogenetics, genetic analysis was completed using the next-generation sequencing method. A Robertsonian-type translocation of two long arms in derivative chromosome 15 was detected, defining the patient's karyotype as 45,XX,der(15;15)(q10;q10)dn. Haplotype analysis confirmed the presence of paternal uniparental disomy, indicating that the case carried a de novo rob(15q;15q) translocation. The literature, suggests that AS cases with UPD may exhibit milder clinical features compared to those with microdeletion. Consequently, AS cases involving UPD of chromosome 15 can sometimes be overlooked. Therefore, the case presented here serves as an example highlighting the need to evaluate individuals with translocations involving der(15;15) identified through conventional cytogenetics for potential UPD.
Less than 1% of the cases with Angelman syndrome (AS) are caused by chromosomal rearrangements. This category of AS is not well defined and may manifest atypical phenotypes. Here, we report a girl with AS due to der(13)t(13;15)(q14.1;q12)mat. SNP array detected the precise deletion/duplication points and the parental origin of the 15q deletion. Multicolor FISH confirmed a balanced translocation t(13;15)(q14.1;q12) in her mother. Her facial appearance showed some features of dup(13)(pter→q14). Also, she lacked the most characteristic and unique behavioral symptoms of AS, i.e., frequent laughter, happy demeanor, and easy excitability. A review of the literature indicated that AS cases caused by chromosomal rearrangements can be classified into 2 major categories and 4 groups. The first category is paternal uniparental disomy 15, which is subdivided into isodisomy by de novo rob(15;15) and heterodisomy caused by paternal translocation. The second category is the deletion of the AS locus due to maternal reciprocal translocation, which is subdivided into 2 groups associated with partial monosomy by 3:1 segregation and partial trisomy by adjacent-2 segregation. Classification into these categories facilitates the understanding of the mechanisms of chromosomal rearrangements and helps in accurate diagnosis and genetic counseling of these rare forms of AS.
