RESUMO
BACKGROUND: Primary hereditary microcephaly (MCPH) comprises a large group of autosomal recessive disorders mainly affecting cortical development and resulting in a congenital impairment of brain growth. Despite the identification of >25 causal genes so far, it remains a challenge to distinguish between different MCPH forms at the clinical level. METHODS: 7 patients with newly identified mutations in CDK5RAP2 (MCPH3) were investigated by performing prospective, extensive and systematic clinical, MRI, psychomotor, neurosensory and cognitive examinations under similar conditions. RESULTS: All patients displayed neurosensory defects in addition to microcephaly. Small cochlea with incomplete partition type II was found in all cases and was associated with progressive deafness in 4 of them. Furthermore, the CDK5RAP2 protein was specifically identified in the developing cochlea from human fetal tissues. Microphthalmia was also present in all patients along with retinal pigmentation changes and lipofuscin deposits. Finally, hypothalamic anomalies consisting of interhypothalamic adhesions, a congenital midline defect usually associated with holoprosencephaly, was detected in 5 cases. CONCLUSION: This is the first report indicating that CDK5RAP2 not only governs brain size but also plays a role in ocular and cochlear development and is necessary for hypothalamic nuclear separation at the midline. Our data indicate that CDK5RAP2 should be considered as a potential gene associated with deafness and forme fruste of holoprosencephaly. These children should be given neurosensory follow-up to prevent additional comorbidities and allow them reaching their full educational potential. TRIAL REGISTRATION NUMBER: NCT01565005.
Assuntos
Proteínas de Ciclo Celular/genética , Doenças Cocleares/genética , Microcefalia/genética , Proteínas do Tecido Nervoso/genética , Criança , Pré-Escolar , Cóclea/diagnóstico por imagem , Cóclea/metabolismo , Cóclea/patologia , Doenças Cocleares/diagnóstico por imagem , Doenças Cocleares/patologia , Anemia de Fanconi/genética , Anemia de Fanconi/patologia , Feminino , Humanos , Hipotálamo/diagnóstico por imagem , Hipotálamo/patologia , Lactente , Imageamento por Ressonância Magnética , Masculino , Microcefalia/diagnóstico por imagem , Microcefalia/patologia , Mutação , Neurogênese/genética , Linhagem , Retina/diagnóstico por imagem , Retina/patologiaRESUMO
BACKGROUND: Usher syndrome type 1 needs to be diagnosed at early age in order to timely manage speech therapy, cochlear implantation, and genetic counseling. Few data are available regarding electroretinographic testing before the age of six years. AIM: To describe electroretinographic changes in young children with Usher syndrome type 1. METHODS: Retrospective study of fourteen patients. Age at first neurophysiologic testing was between 17 months and 5 years 4 months. Electroretinogram was performed using flash stimulation in mesopic conditions in the conscious child. Analysis was focused on the amplitudes and latencies of a- and b-waves. RESULTS: Whatever the age, an abnormal fundus was always confirmed with an absent electroretinogram. The youngest patient with absent electroretinogram was 17 month-old. When recorded on and after the 29th month of age, electroretinogram was absent in all cases, including 6 patients with normal fundus. In three patients a low-amplitude electroretinogram was present at first recording within the 26th and 27th months. CONCLUSION: Electroretinogram showed retinopathy in young children with Usher syndrome type 1, even in the absence of fundoscopic signs of retinal degeneration.
