Symptoms may include short-limbed dwarfism due to skeletal dysplasia, variable level of immunodeficiency, and predisposition to cancer.

[2] An association between mutations near or within the ncRNA component of RNase MRP, RMRP, has been identified.

[3][4][5][6] The endoribonuclease RNase MRP is a complex of RNA molecule and several proteins and it participates in cleavage of mitochondrial primers responsible for DNA replication and in pre-rRNA processing in the nucleolus.

In the study of 108 Finnish patients with CHH, mild to moderate form of lymphopenia was detected along with decreased delayed type of hypersensitivity and impaired responses to phytohemagglutinin.

[10] This leads to susceptibility to and, in some more severe cases, mortality from infections early in childhood.