You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Disease"].

Please return the output as a JSON object of the format: {"Disease" : ["COVID-19", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Type II human complement C2 deficiency. Allele-specific amino acid substitutions (Ser189 --> Phe; Gly444 --> Arg) cause impaired C2 secretion. Type II complement protein C2 deficiency is characterized by a selective block in C2 secretion. The Type II C2 null allele (C2Q0) is linked to two major histocompatibility haplotypes (MHC) that differ from the MHC of the more common Type I C2 deficiency. To determine the molecular basis of Type II deficiency the two Type II C2Q0 genes were isolated and transfected separately into L-cells. Subsequent molecular biology, biosynthetic, and immunofluorescence studies demonstrated that C2 secretion is impaired in Type II C2 deficiency because of different missense mutations at highly conserved residues in each of the C2Q0 alleles. One is in exon 5 (nucleotide C566 -- > T; Ser189 -- > Phe) of the C2Q0 gene linked to the MHC haplotype A11, B35, DRw1, BFS, C4A0B1. The other is in exon 11 (G1930 -- > A; Gly444 -- > Arg) of the C2Q0 gene linked to the MHC haplotype A2, B5, DRw4, BFS, C4A3B1. Each mutant C2 gene product is retained early in the secretory pathway. These mutants provide models for elucidating the C2 secretory pathway..
{"Disease": ["Type II deficiency", "Type I C2 deficiency", "Type II C2 deficiency", "Type II complement protein C2 deficiency", "Type II human complement C2 deficiency"]}