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Basal Cell Nevus Syndrome
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Priyanka Chhadva, Pete Setabutr
The PTCH1 gene shows broad allelic heterogeneity, with 51 germline mutations identified through the analysis of patients with BCNS [9]. Of the known pathogenic variants, 65% contain premature termination codon (predicting a protein truncation), 16% are missense mutations, 13% have splice site, 6% are (multi)exon or large-scale deletions or rearrangements [12–16]. A condition associated with large chromosomal deletions in the PTCH1 gene is referred to as 9q22.3 microdeletion syndrome, in which developmental delay and/or intellectual disability, metopic craniosynostosis, obstructive hydrocephalus, pre- and postnatal macrosomia, and seizures, in addition to the features of BCNS, are observed.
Immunology
Published in Rachel U Sidwell, Mike A Thomson, Concise Paediatrics, 2020
Rachel U Sidwell, Mike A Thomson
The autosomal dominant 22q11 microdeletion syndrome (DiGeorge anomaly) is caused by microdeletions of chromosome 22q, and includes the velocardiofacial (Shprintzen) syndrome.
Approach to women with a previous child with a genetic disorder
Published in Minakshi Rohilla, Recurrent Pregnancy Loss and Adverse Natal Outcomes, 2020
A chromosome sample is denatured on a glass slide so that the DNA is single stranded and then mixed with a fluorescent DNA probe. This is a sequence of DNA that is complementary to the sequence of interest. The sequence-specific hybridization is formed by the overnight incubation. If a chromosomal preparation shows only one signal, then there is a deletion of the second copy of DNA sequence; if there are more than two signals, then duplication is present. Fluorescence in situ hybridization (FISH) can identify only a known microdeletion syndrome and therefore it is only used to confirm a specific diagnosis suspected from clinical features.
Prenatal sonographic findings in a cohort of foetuses with a confirmed 22q11.2 microdeletion at a single Chinese Tertiary Centre
Published in Journal of Obstetrics and Gynaecology, 2022
Xiang-Yi Jing, Yong-Ling Zhang, Li Zhen, Yan-Lin Li, Dong-Zhi Li
22q11.2 deletion (del22q11.2) is now the most common microdeletion syndrome encountered by obstetricians and paediatricians, with a reported prevalence of 1/2,000–1/6,000 live births (Bassett et al. 2011). Patients present with highly variable clinical phenotypes, even within families with the same deletion, ranging from mild to severe neurodevelopmental and psychiatric symptoms. Congenital heart defects (CHDs), especially conotruncal malformations, are the most frequent structural anomalies observed in del22q11.2 patients, accounting for 60–80%% of total cases (Goldmuntz 2020). Other manifestations include facial dysmorphia, hypocalcaemia, palate and speech disorders, gastrointestinal disorders, immunodeficiency, and mental health disorders. Therefore, prenatal diagnosis is important for parental counselling, including early decision making for termination or preparation for long-term management of associated medical, surgical and psychiatric conditions.
A reappraisal of atypical absence seizures in children and adults: therapeutic implications
Published in Expert Opinion on Pharmacotherapy, 2019
Francesco Brigo, Pasquale Striano, Vicenzo Belcastro
15q13.3 microdeletion syndrome features intellectual disability, autism spectrum disorders, and epilepsy. The 15q13.3 microdeletion is a specific risk factor for epilepsy, being detected in about 1% of the patients with genetic-generalized epilepsies/idiopathic-generalized epilepsies (GGEs/IGEs) with or without other neurologic manifestations [23]. Atypical absences with eyelid myoclonia seem to be the common denominator of the epileptic phenotype in these patients. Absence status epilepticus and myoclonic absences are also commonly encountered in these patients [24]. Interictal EEG shows brief spike and waves or polyspike and wave discharge that could resemble what is observed in IGE/GGE. The clinical course is not always benign, with seizures persisting in the elderly, response to treatment is partial, and seizure control is overall difficult.
Novel applications of array comparative genomic hybridization in molecular diagnostics
Published in Expert Review of Molecular Diagnostics, 2018
With the advent of noninvasive prenatal screening (NIPS) integrated into clinical practice in 2011, this technique now utilizes massively parallel sequencing analysis of cell-free fetal DNA (cffDNA) in maternal plasma and has achieved highly accurate detection of trisomy 21 (sensitivity 99%), trisomy 18 (sensitivity 96.8%), and trisomy 13 (sensitivity 92.1%). Nonetheless, discordant results between NIPS and traditional karyotyping have been obtained due to inherent biological factors and because cffDNA is derived from both maternal and placental tissues [68]. American College of Obstetrics and Gynecology (ACOG) recommends that NIPS be one of the screening test options for fetal aneuploidy [69]. The NIPS later is expanded to screening for a relatively common microdeletion syndrome. After testing of 712 clinical samples by CMA in our laboratory to confirm results of a cffDNA screening, positive predictive value ranged from 0% for detection of Cri-du Chat syndrome and Prader-Willi/Angelman syndrome to 14% for 1p36 deletion syndrome and 21% for 22q11.2 deletion syndrome [65]. CMA is one of the methods suitable for confirming aneuploidy or a microdeletion syndrome.