Genetic analysis and model of the AP3 complex. (A) Electropherograms of the section of exon 32 harboring the homozygous deletion in the patient. The deletion leads to a frameshift at codon 1189 and a termination codon after 7 residues. The encoded wild-type peptide sequence is shown at the top, and the codons of the mutant sequence are shown below the DNA sequences. The parents are heterozygous for the deletion as expected. For technical reasons, the reverse strand was sequenced in the DNA sample of the father but the complementary sequence is depicted here (ie, it is shown in the same direction as the other samples). (B) Model of the AP3 protein complex in the ubiquitous and the neuronal form (adapted from Odorizzi et al31 ). AP3δ is an essential part of both complexes, whereas AP3β3A, mutated in HPS2, is substituted by AP3β3B in neuronal cells.
