Mutation in Rab3 GTPase-activating protein (RAB3GAP) noncatalytic subunit in a kindred with Martsolf syndrome.
We identified a homozygous missense mutation in the noncatalytic subunit (RAB3GAP2) of RAB3GAP that results in abnormal splicing in a family with congenital cataracts, hypogonadism, and mild mental retardation (Martsolf syndrome). Recently, mutations in the catalytic subunit of RAB3GAP (RAB3GAP1), a key regulator of calcium-mediated hormone and neurotransmitter exocytosis, were reported in Warburg micro syndrome, a severe neurodevelopmental condition with overlapping clinical features. RAB3GAP is a heterodimeric protein that consists of a catalytic subunit and a noncatalytic subunit encoded by RAB3GAP1 and RAB3GAP2, respectively. We performed messenger RNA-expression studies of RAB3GAP1 and RAB3GAP2 orthologues in Danio rerio embryos and demonstrated that, whereas developmental expression of rab3gap1 was generalized (similar to that reported elsewhere in mice), rab3gap2 expression was restricted to the central nervous system. These findings are consistent with RAB3GAP2 having a key role in neurodevelopment and may indicate that Warburg micro and Martsolf syndromes represent a spectrum of disorders. However, we did not detect RAB3GAP2 mutations in patients with Warburg micro syndrome. These findings suggest that RAB3GAP dysregulation may result in a spectrum of phenotypes that range from Warburg micro syndrome to Martsolf syndrome.
Section of Medical and Molecular Genetics, University of Birmingham, Birmingham, United Kingdom.
Irene A
IA
Aligianis
Neil V
NV
Morgan
Marina
M
Mione
Colin A
CA
Johnson
Elisabeth
E
Rosser
Raoul C
RC
Hennekam
Gill
G
Adams
Richard C
RC
Trembath
Daniela T
DT
Pilz
Neil
N
Stoodley
Anthony T
AT
Moore
Steve
S
Wilson
Eamonn R
ER
Maher
D000015:Abnormalities, Multiple / Q000235:genetics*; D020134:Catalytic Domain; D006801:Humans; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D012326:RNA Splicing; D013577:Syndrome; D020692:rab3 GTP-Binding Proteins / Q000235:genetics*
C580955:RAB3GAP1 protein, human; D020692:rab3 GTP-Binding Proteins