ABSTRACT
Abstract The cri-du-chat syndrome is caused by a deletion on the short arm of chromosome number 5. The size of genetic material loss varies from the 5p15.2 region only to the whole arm. Prevalence rates range between 1:15000 and 1:50000 live births. Diagnosis is suspected on infants with a high-pitched (cat-like) cry, facial dysmorfism, hypotonia and delayed psychomotor development. In adults, phenotypic findings are less specific. It is confirmed through high-resolution G-banding karyotype, fluorescent in situ hybridization or microarray-based comparative genomic hybridization (a-CGH). The following is the case report of a 21-year-old female patient with severe mental retardation and trichotillomania, who does not control sphincters and does not bathe or eat by herself. Her communication is based only on sounds and dysmorphic facies. The G-band karyotype reported is 46, XX. a-CGH shows 18.583Mb interstitial microdeletion in 5p15.33p14.3, including the cri-du-chat critical region. In children or adults with unexplained mental retardation and normal karyotype results (like this case), an a-CGH should be performed to make an etiological diagnosis, establish the prognosis, order additional medical tests and specific treatments, and offer appropriate genetic counseling.
Resumen El síndrome de cri du chat o del maullido de gato es causado por una deleción en el brazo corto del cromosoma 5; el tamaño de la pérdida de material genético varía desde solo la región 5p15.2 hasta el brazo entero. La prevalencia va desde 1 por 15 000 habitantes hasta 1 por 50 000 habitantes. Su diagnóstico se puede confirmar con cariotipo con bandas G de alta resolución, hibridación fluorescente in situ o hibridación genómica comparativa por microarreglos (HGCm); este se sospecha en infantes con un llanto similar al maullido de un gato, fascies dismórficas, hipotonía y retardo del desarrollo psicomotor; sin embargo, en los adultos afectados los hallazgos fenotípicos son menos específicos. Se presenta el caso de una mujer de 21 años con retardo mental severo y tricotilomanía, que no controla esfínteres y no se baña ni come sola; solo emite ruidos y tiene facies dismórficas. El cariotipo de bandas G es reportado 46, XX y la HGCm muestra microdeleción de 18.583Mb en 5p15.33p14.3, incluyendo región crítica de cri du chat. En pacientes de este tipo se debe realizar HGCm para hacer un diagnóstico etiológico, establecer un pronóstico, ordenar pruebas médicas adicionales y tratamientos específicos y realizar la adecuada asesoría genética.
ABSTRACT
5p deletion syndrome, also known as Cri-du-Chat syndrome, is a chromosomal abnormality caused by a deletion in the short arm of chromosome 5. Clinical features of 5p deletion syndrome are difficult to identify prenatally by ultrasound examination, thus most cases of 5p deletion syndrome have been diagnosed postnatally. Here, we report eight cases of 5p deletion syndrome diagnosed prenatally, but were unable to find common prenatal ultrasound findings among these cases. However, we found that several cases of 5p deletion syndrome were confirmed prenatally when karyotyping was performed on the basis of abnormal findings in a prenatal ultrasound scan. Hence, it is necessary to carefully perform prenatal ultrasonography for detection of rarer chromosomal abnormalities as well as common aneuploidy.