The GPR56 is grouped in the B family of GPCRs. This GPCR group have long N termini characterized by an extracellular “cysteine box” and hydrophilic, potentially mucin-rich. The cysteine box contains four conserved cysteines and two tryptophans arranged in a specific fashion (C-x2-W-x6-16-W-x4-C-x10-22-C-x-C) just before the first transmembrane domain and serves as a cleavage site in some members of this group of G protein–coupled receptors. Although, the molecular and cellular mechanisms of how GPR56 regulates brain development remain largely unknown. These types of receptors play an essential role in biological processes including embryonic development, central nervous system (CNS), immune system, and tumorigenesis. GPCR classification Mode of inheritance Parents of a proband :::::::::::*The parents of an affected individual are obligate heterozygotes and therefore carry one mutant allele. :::::::::::*Heterozygotes (carriers) are asymptomatic. Sibs of a proband :::::::::::*At conception, each sibling of an affected individual has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. :::::::::::*Once an at-risk sibling is known to be unaffected, the risk of his/her being a carrier is 2/3. :::::::::::*Heterozygotes (carriers) are asymptomatic. Offspring of a proband :::::::::::*Offspring of a proband are obligate heterozygotes and will therefore carry one mutant allele. :::::::::::*In populations with a high rate of consanguinity, the offspring of a person with GPR56-related BFPP and a reproductive partner who is a carrier of GPR56-related BFPP have a 50% chance of inheriting two GPR56 disease-causing alleles and having BFPP and a 50% chance of being carriers. Other family members of a proband. :::::::::::*Each sibling of the proband's parents is at a 50% risk of being a carrier
Bilateral frontoparietal polymicrogyria
Hippocampal sclerosis
Posterior cortical atrophy
Polymicrogyria
Periodic lateralized epileptiform discharges
Gray matter heterotopia
Agenesis of the corpus callosum
Olivopontocerebellar atrophy