RESUMEN
The microcephaly-capillary malformation (MIC-CAP) syndrome is a life-threatening disease caused by biallelic mutations of the STAMBP gene, which encodes an endosomal deubiquitinating enzyme. To establish a suitable preclinical animal model for clinical therapeutic practice, we generated a central nervous system (CNS)-specific Stambp knockout mouse model (Stambp Sox1-cKO) that phenocopies Stambp null mice including progressive microcephaly, postnatal growth retardation and complete penetrance of preweaning death. In this MIC-CAP syndrome mouse model, early-onset neuronal death occurs specifically in the hippocampus and cortex, accompanied by aggregation of ubiquitinated proteins, and massive neuroinflammation. Importantly, neonatal AAV9-mediated gene supplementation of Stambp in the brain could significantly improve neurological defects, sustain growth, and prolong the lifespan of StambpSox1-cKO mice. Together, our findings reveal a central role of brain defects in the pathogenesis of STAMBP deficiency and provide preclinical evidence that postnatal gene replacement is an effective approach to cure the disease.
RESUMEN
Mutations in STAMBP have been well-established to cause congenital human microcephaly-capillary malformation (MIC-CAP) syndrome, a rare genetic disorder characterized by global developmental delay, severe microcephaly, capillary malformations, etc. Previous biochemical investigations and loss-of-function studies in mice have provided insights into the mechanism of STAMBP, however, it remains controversial how STAMBP deficiency leads to malformation of those affected tissues in patients. In this study, we investigated the function and underlying mechanism of STAMBP during neural differentiation of human embryonic stem cells (hESCs). We found that STAMBP is dispensable for the pluripotency maintenance or neural differentiation of hESCs. However, neural progenitor cells (NPCs) derived from STAMBP-deficient hESCs fail to be long-term maintained/expanded in vitro. We identified the anti-apoptotic protein CFLAR is down-regulated in those affected NPCs and ectopic expression of CFLAR rescues NPC defects induced by STAMBP-deficiency. Our study not only provides novel insight into the mechanism of neural defects in STAMBP mutant patients, it also indicates that the death receptor mediated apoptosis is an obstacle for long-term maintenance/expansion of NPCs in vitro thus counteracting this cell death pathway could be beneficial to the generation of NPCs in vitro.
RESUMEN
Microcephaly-Capillary Malformation syndrome (MIC-CAP) is a rare genetic disorder reported in 18 individuals to date. The clinical features typically include microcephaly, multiple cutaneous capillary malformations, seizures, neurologic impairment, and global developmental delay. Currently, there is little published information about the natural history and long-term outcomes for individuals with MIC-CAP. In this report, we provide follow up on two previously published patients and describe four new patients. The included patients highlight increased variability in the clinical spectrum and provide novel information regarding medical complications and recurrent variants.
Asunto(s)
Microcefalia , Malformaciones del Sistema Nervioso , Malformaciones Vasculares , Capilares/anomalías , Humanos , Microcefalia/diagnóstico , Microcefalia/genética , Malformaciones Vasculares/diagnóstico , Malformaciones Vasculares/genéticaRESUMEN
We describe two brothers from a consanguineous family of Egyptian ancestry, presenting with microcephaly, apparent global developmental delay, seizures, spasticity, congenital blindness, and multiple cutaneous capillary malformations. Through exome sequencing, we uncovered a homozygous missense variant in STAMBP (p.K303R) in the two siblings, inherited from heterozygous carrier parents. Mutations in STAMBP are known to cause microcephaly-capillary malformation syndrome (MIC-CAP) and the phenotype in this family is consistent with this diagnosis. We compared the findings in the present brothers with those of earlier reported patients. © 2016 Wiley Periodicals, Inc.
Asunto(s)
Capilares/anomalías , Complejos de Clasificación Endosomal Requeridos para el Transporte/genética , Homocigoto , Microcefalia/diagnóstico , Microcefalia/genética , Ubiquitina Tiolesterasa/genética , Malformaciones Vasculares/diagnóstico , Malformaciones Vasculares/genética , Encéfalo/patología , Consanguinidad , Variaciones en el Número de Copia de ADN , Análisis Mutacional de ADN , Exoma , Facies , Estudios de Asociación Genética , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Imagen por Resonancia Magnética , Masculino , Mutación , Linaje , Fenotipo , Hermanos , SíndromeRESUMEN
Microcephaly-capillary malformation syndrome (MIC-CAP syndrome) is a newly recognized autosomal recessive congenital neurocutaneous central nervous system disorder characterized by severe microcephaly, early-onset seizures, profound psychomotor disability, and multiple cutaneous capillary lesions. In addition, affected patients have variable dysmorphic facial features and hypoplastic distal phalanges. It is distinctively caused by mutations in a newly characterized gene, STAMBP, encoding the deubiquitinating (DUB) isopeptidase that has a key role in cell surface receptor-mediated endocytosis and sorting. Herein, we describe an Arab family of two siblings with classic features of MIC-CAP syndrome that harbor a novel predicted splice mutation in STAMBP, which additionally display previously unreported findings of congenital hypothyroidism and alopecia areata.