<i>CDK5RAP2</i> primary microcephaly is associated with hypothalamic, retinal and cochlear developmental defects
Hala Nasser, Liza Vera, Monique Elmaleh, Katharina Steindl, Pascaline Létard, N. Teissier, Anais Ernault, Fabien Guimiot, Alexandra Afenjar, Marie Laure Moutard, Delphine Héron, Yves Alembik, M. Momtchilova, Paolo Milani, Nathalie Kubis, Nathalie Pouvreau, Marcella Zollino, Sophie Guilmin‐Crépon, Florentia Kaguelidou, Pierre Gressèns, Alain Verloès, Anita Rauch, Vincent El Ghouzzi, Séverine Drunat, Sandrine Passemard
Abstract
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: (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: 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.