Novel microcephalic primordial dwarfism disorder associated with variants in the centrosomal protein ninein.

J Clin Endocrinol Metab
Authors
Keywords
Abstract

CONTEXT: Microcephalic primordial dwarfism (MPD) is a rare, severe form of human growth failure in which growth restriction is evident in utero and continues into postnatal life. Single causative gene defects have been identified in a number of patients with MPD, and all involve genes fundamental to cellular processes including centrosome functions.

OBJECTIVE: The objective of the study was to find the genetic etiology of a novel presentation of MPD.

DESIGN: The design of the study was whole-exome sequencing performed on two affected sisters in a single family. Molecular and functional studies of a candidate gene were performed using patient-derived primary fibroblasts and a zebrafish morpholino oligonucleotides knockdown model.

PATIENTS: Two sisters presented with a novel subtype of MPD, including severe intellectual disabilities.

MAIN OUTCOME MEASURES: NIN, encoding Ninein, a centrosomal protein critically involved in asymmetric cell division, was identified as a candidate gene, and functional impacts in fibroblasts and zebrafish were studied.

RESULTS: From 34,606 genomic variants, two very rare missense variants in NIN were identified. Both probands were compound heterozygotes. In the zebrafish, ninein knockdown led to specific and novel defects in the specification and morphogenesis of the anterior neuroectoderm, resulting in a deformity of the developing cranium with a small, squared skull highly reminiscent of the human phenotype.

CONCLUSION: We identified a novel clinical subtype of MPD in two sisters who have rare variants in NIN. We show, for the first time, that reduction of ninein function in the developing zebrafish leads to specific deficiencies of brain and skull development, offering a developmental basis for the myriad phenotypes in our patients.

Year of Publication
2012
Journal
J Clin Endocrinol Metab
Volume
97
Issue
11
Pages
E2140-51
Date Published
2012 Nov
ISSN
1945-7197
URL
DOI
10.1210/jc.2012-2150
PubMed ID
22933543
PubMed Central ID
PMC3485598
Links
Grant list
K12 HD052896 / HD / NICHD NIH HHS / United States
K23 HD073351 / HD / NICHD NIH HHS / United States
5K12HD052896 / HD / NICHD NIH HHS / United States