| Disease Name | phenotype | Inheritance Mode | Chr Location | Mutation Type | Gene Name | mRNA Variant | Protein Variant | Effect | Reference |
| Nail Dysplasia Type 4 (anonychia/hyponychia) | Absence or severe hypoplasia of nails | Autosomal Recessive | 20p13 | Missense | RSPO4 | 3G>A | Met1Ile | Amino Acid Substitution | 2008/Ishii et al., 2008 |
| Nail Dysplasia Type 4 (anonychia/hyponychia) | Absence or severe hypoplasia of nails | Autosomal Recessive | 20p13 | Splice site | RSPO4 | IVS2-1G>A | Skipping exon 2 | Frame shift mutation & PTC | 2008/Ishii et al., 2008 |
| Nail Dysplasia Type 4 (anonychia/hyponychia) | Absence or severe hypoplasia of nails | Autosomal Recessive | 20p13 | Missense | RSPO4 | 353G>A | Cys118Tyr | Amino Acid Substitution | 2006/Blaydon et al., 2006 |
| Nail Dysplasia Type 4 (anonychia/hyponychia) | Absence or severe hypoplasia of nails | Autosomal Recessive | 20p13 | Missense | RSPO4 | 199G>C | Gly67Arg | Amino Acid Substitution | 2009/Chishti et al., 2009 |
| Nail Dysplasia Type 4 (anonychia/hyponychia) | Absence or severe hypoplasia of nails | Autosomal Recessive | 20p13 | Missense | RSPO4 | 178C>T | Arg60Trp | Amino Acid Substitution | 2012/Khan et al., 2012 |
| Nail Dysplasia Type 4 (anonychia/hyponychia) | Absence or severe hypoplasia of nails | Autosomal Recessive | 20p13 | Nonsense | RSPO4 | 18C>A | Cys6* | Premature Termination | 2013/Wasif & Ahmad, 2013 |
