Asesoramiento genético: 18q Síndrome de deleción

· 18q Deletion Syndrome Contents 1 Genetic Etiology 2 Incidence and Carrier Frequency 3 Clinical Features 4 Age of onset, natural history, life span 5 Testing 6 Surveillance, management, and treatment options 7 Psychosocial issues 8 Referencias 9 Notes Genetic Etiology Caused by the deletion of the long arm of chromosome 18 (o, más a menudo, a section of it) Incidence and Carrier Frequency This disorder has been documented in less than 100 Casos 80% of cases occur due to de novo mutations; 10% of cases are due to a parental translocation; the remaining 10% are mosaic, resulting in a less severe phenotype Clinical Features This syndrome is variable in its severity. The symptoms usually correlate with the size of the deletion. Key features: Short stature (80% of patients are below the fifth percentile) Mental impairment/retardation (100% of patients, most with IQs from 40-85) Hypotonia Hearing impairment (61%) Ear anomalies Narrow or atretic auditory canals (50%) Prominent antihelix or antitragus (84%) Low-set ears Foot deformities Club foot (21%) Abnormal implantation of the second toe (84%) Endocrine problems IgA deficiency (30%) Growth hormone deficiency Facial dysmorphism Microcephaly (68%) "Carp-like" boca (87%) Midface hypoplasia (85%) Deeply-set eyes Slanted palpebral fissures Hypertelorism Epicanthic folds (42%) Strabismus (34%) Nystagmus (80%) Pale optic discs (84%) Broad nasal bridge (81%) Cleft lip (9%) Cleft palate (29%) Abnormal genitalia Females: hypoplastic labia minora (47%) Males: cryptorchidism (52%), hipospadias, micropenis, inguinal hernia (13%) Poor myelination of central white matter tracts with relatively normal myelination of corpus callosum Hand anomalies Tapered fingers (90%) Proximal thumb with short first metacarpal Transverse palmar creases (92%) High whorl patterns on fingertips and high total finger ridge count Dimples on the knuckles Age of onset, natural history, life span Symptoms are apparent from birth in most cases Natural history: Most patients have IQs between 40 y 85. Short stature is common, as are various hearing and vision problems. Behavioral problems can often occur, causing patients to exhibit autistic-like behaviors or obnoxiousness. These symptoms are variable, so a patient with a smaller deletion will have a milder phenotype than will a patient missing all of 18q. Life span is variable, but decreased from the general population Testing Diagnosis is confirmed by chromosome studies Surveillance, management, and treatment options Patients should be monitored by audiology, opthamology, genética, neurology, orthopedics, immunology, physical therapy, occupational therapy, speech therapy, and Early Intervention. Psychosocial issues Guilt, miedo, ansiedad, enojo, sadness, and disbelief are common emotions associated with this diagnosis. Parents may feel overwhelmed because of all of the care these patients require. Financial concerns, issues affecting family dynamics, and who will provide care for this patient are all things that should be addressed with parents. References OMIM, Smith's, Chromosomal Syndromes: Common and/or Well-Known Syndromes Notes The information in this outline was last updated in 2002. Material obtained under GFDL Licence from http://en.wikibooks.org/wiki/Handbook_of_Genetic_Counseling Permission is granted to copy, distribuir y/o modificar este documento bajo los términos de la Licencia de Documentación Libre GNU, Versión 1.2 o cualquier versión posterior publicada por la Free Software Foundation; sin secciones invariantes, sin textos de portada, y sin textos de contraportada. Se incluye una copia de la licencia en la sección titulada "Licencia de documentación libre GNU."

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