[Low stature in males with normal phenotype and 45,X/46,XY mosaicism]. / Talla baja en varones con fenotipo normal y mosaicismo 45,X/46,XY.

There is wide variation in the clinical expression of 45,X/46,XY mosaicism. Ninety percent of prenatally diagnosed boys have normal male phenotype at birth, while those diagnosed postnatally show a wide spectrum of phenotypes, ranging from Turner syndrome, mixed gonadal dysgenesis, and male pseudohermaphroditism to apparent normality. We report the clinical, cytogenetic, endocrinologic and histologic findings in three boys with an apparently normal male phenotype and 45,X/46,XY mosaicism who were diagnosed postnatally because of their short stature. With the exception of one patient with Turner stigmata, no other abnormal features were found. No correlation between the proportion of 45,X/46,XY cell lines in blood, gonads and phenotype was found. Both prenatally and postnatally diagnosed boys with normal male phenotype must be followed-up because they can develop late-onset abnormalities, such as dysgenetic testes leading to infertility or neoplastic transformation, and short stature, which could be improved with growth hormone therapy.

Talla baja en varones con fenotipo normal y mosaicismo 45, X/46, XY / Low stature in males with normal phenotype and 45, X/46, XY mosaicism

El mosaicismo 45,X/46,XY tiene una amplia expresividad clínica. El 90 % de los casos de diagnóstico prenatal son varones fenotípicamente normales, mientras que los casos de diagnóstico posnatal engloban un amplio espectro clínico que incluye síndrome de Turner, disgenesia gonadal mixta, seudohermafroditismo masculino y varones aparentemente normales. Se indican los hallazgos clínicos, endocrinológicos, citogenéticos e histológicos de 3 pacientes con fenotipo masculino normal y mosaicismo 45,X/46,XY de diagnóstico posnatal durante su estudio por talla baja. Sólo uno de los pacientes presentaba rasgos turnerianos. No se ha encontrado correlación entre la proporción de líneas celulares 45,X y 46,XY en sangre, gónadas y fenotipo. La posibilidad de desarrollar complicaciones como disgenesia del tejido gonadal con riesgo de malignización e infertilidad y talla baja susceptible de beneficiarse del tratamiento con hormona de crecimiento implica la necesidad de un seguimiento estrecho sobre todo en aquellos pacientes de diagnóstico prenatal y posnatal con fenotipo normal (AU)

There is wide variation in the clinical expression of 45,X/46,XY mosaicism. Ninety percent of prenatally diagnosed boys have normal male phenotype at birth, while those diagnosed postnatally show a wide spectrum of phenotypes, ranging from Turner syndrome, mixed gonadal dysgenesis, and male pseudohermaphroditism to apparent normality. We report the clinical, cytogenetic, endocrinologic and histologic findings in three boys with an apparently normal male phenotype and 45,X/46,XY mosaicism who were diagnosed postnatally because of their short stature. With the exception of one patient with Turner stigmata, no other abnormal features were found. No correlation between the proportion of 45,X/46,XY cell lines in blood, gonads and phenotype was found. Both prenatally and postnatally diagnosed boys with normal male phenotype must be followed-up because they can develop late-onset abnormalities, such as dysgenetic testes leading to infertility or neoplastic transformation, and short stature, which could be improved with growth hormone therapy (AU)