| Nucleotide change | Protein consequence | Variant class | Zygosity | Review-reported rsID / allele-frequency field | Functional effect | Phenotype and nomenclature notes |
|---|---|---|---|---|---|---|
| `c.1049+27C>T` | `p.G350fsX351` | Intronic aberrant splice-donor creation; frameshift and truncation | Homozygous | rs2107055197; none reported | Preferential aberrant splicing produces a truncated receptor lacking transmembrane domains 5–7 and the cytoplasmic C-terminus; low-level normal transcript remains; severe loss of function | Type II BOCD, consistent with residual transcript. The 2007 legacy designation was “intron M4 +27C>T”; the 2025 review maps it as `c.1049+27C>T`, `p.G350fsX351` (pqac-00000004, pqac-00000021, pqac-00000031, pqac-00000034) |
| `c.1148G>A` | `p.L373_R383del` | Splice-acceptor alteration causing an in-frame deletion | Compound heterozygous | rs398122843; 0.7 | Severe receptor loss of function | Severe Blomstrand chondrodysplasia; the nucleotide change has also been reported in PTH1R-related primary failure of tooth eruption, indicating genotype–phenotype overlap (pqac-00000005, pqac-00000020, pqac-00000031) |
| `c.310C>T` | `p.R104X` | Nonsense; premature termination | Homozygous | rs121434604; 0.14 | Produces only the signal peptide and first 79 amino acids, eliminating functional extracellular, transmembrane, and intracellular domains; complete or severe loss of function | Classical severe type I BOCD. The 2007 legacy description gives `338C>T` with `R104X`; the 2025 review uses `c.310C>T`, `p.R104X` (pqac-00000016, pqac-00000031, pqac-00000032, pqac-00000034) |
| `c.395C>T` | `p.P132L` | Missense | Homozygous | rs121434599; 0.36 | Markedly impaired PTHrP binding and signaling with low residual activity; classified as severe loss of function | Recurrently associated with relatively milder type II BOCD, supporting a residual-activity–severity relationship (pqac-00000004, pqac-00000008, pqac-00000016, pqac-00000031, pqac-00000032) |
| `c.1093delG` | `p.V365CfsX141` | Single-nucleotide deletion; frameshift and premature termination | Homozygous | rs1304201852; 0.44 | Severe receptor loss of function | Severe lethal Blomstrand chondrodysplasia; type assignment was not specified in the extracted review table (pqac-00000001, pqac-00000003, pqac-00000031) |
| Interpretation note | — | — | — | Values above are transcribed from the 2025 review’s field labeled “allele frequency” | These values are review-reported and are not necessarily validated population allele frequencies or percentages | Verify against the underlying population database and version before reuse (pqac-00000031) |


*Table: Knowledge-base summary of five established severe PTH1R loss-of-function alleles associated with lethal Blomstrand chondrodysplasia. It records functional and phenotype evidence while flagging legacy nomenclature and uncertain review-reported frequency values.*