Expression analysis of six paralogous human hyaluronidase genes clustered on chromosomes 3p21 and 7q31

Two new members of a family of putative hyaluronidase genes involved in glycosaminoglycan catabolism have been identified and mapped by FISH and YAC library screening to chromosome 7q31.3. One of these (HYALP1) is an expressed pseudogene with mutations in the genomic DNA and cDNA. The six members of the hyaluronidase family are grouped into two tightly linked triplets on human chromosomes 3p21.3 (HYAL1, HYAL2, and HYAL3) and 7q31.3 (HYAL4, SPAM1 (PH-20), and HYALP1). This arrangement could arise by an ancient cluster formation, followed by a more recent cluster block-duplication. All of the hyaluronidase genes have unique tissue-specific expression patterns as determined by Northern blot analysis of 23 human tissues. HYAL1, HYAL2, and HYALP1 are widely expressed, but HYAL3 is differentially expressed in bone marrow and testis, while HYAL4 is differentially expressed in placenta and skeletal muscle. SPAM1 (PH-20) was detectable only in testis by Northern blot as previously reported, but was detectable in fetal and placental cDNA libraries by PCR, suggesting a possible role for this gene during embryonic development.