Expert-consensus nosology of the genetic skeletal disorders, following the Nosology of Genetic Skeletal Disorders maintained by the Nosology Committee of the International Skeletal Dysplasia Society (ISDS). This enum encodes the **2023 revision** — the eleventh edition — which contains 771 entries associated with 552 genes, classified into 41 groups (Unger S, Ferreira CR, Mortier GR, et al., Am J Med Genet A 2023;191(5):1164-1209; PMID:36779427, DOI:10.1002/ajmg.a.63132). It supersedes the 2019 revision (10th edition; 461 disorders, 437 genes, 42 groups; Mortier GR et al., PMID:31633310), which dismech encoded first and which is still recorded here as provenance — see "Revision handling" below. The ISDS groups are a flat, non-hierarchical partition: each disorder is deliberately listed exactly once, to avoid redundancy in the Nosology. Group membership is therefore mutually exclusive within the nosology itself, even though the underlying biology frequently spans groups (the table carries explicit "see also" cross-references for those cases). Groups mix organizing principles by design — some molecular (a shared causal gene or gene family), some radiographic (which segment of the growing bone is affected), some anatomical or pathogenetic (craniosynostosis, brachydactyly, osteolysis). Dyadic naming. The headline change in the 2023 revision is the adoption of **dyadic naming**: a phenotypic entity is systematically paired with the gene it arises from ("Geleophysic dysplasia, ADAMTSL2-related"), replacing list numberings and eponyms, which the committee considers "more informative and less prone to errors". That is a claim about disease-entity naming and identity, not about this classification axis, and it is deliberately NOT imported into dismech entry naming here; it is noted so curators reading the 2023 table are not surprised by the disorder names. Curation guidance for dismech: - Assign a group only to entries the ISDS Nosology itself lists, or to entries that are an unambiguous subtype/synonym of a listed disorder. This is a transcription of an expert nosology, not an inference engine; do not extend it to skeletal-phenotype disorders the committee chose not to list. - The slot is multivalued only to accommodate an entry that lumps several distinct nosology disorders. A single listed disorder should carry exactly one group. - Record the provenance in the assignment's ``notes`` — which revision, which group, and the listed disorder name where it differs from the dismech entry name. Neither paper's PubMed record carries per-disorder group placements in its abstract, so a group assignment is not quotable as an evidence snippet; prefer ``notes`` over a snippet the abstract does not actually support. - Do NOT use a deprecated value for new curation. Four values are retained only so existing assignments stay resolvable. Revision handling. Permissible-value **keys are stable identifiers and are not renamed or renumbered when a revision renames or renumbers a group** — the key identifies the group across editions, while the revision's own number and name live in the ``description``. Superseded names are retained as ``structured_aliases`` with ``predicate: EXACT_SYNONYM`` and ``source`` pointing at the revision that used them, so a search for the old name still resolves. Group numbers are emphatically NOT stable across revisions (the brachydactyly groups went from 37/38 to 18/19), which is why they are not part of any key. Where a revision *dissolves* a group rather than renaming it, the old value is kept with ``deprecated:`` plus ``deprecated_element_has_possible_replacement`` pointing at its successor — "possible" rather than "exact" because a merge makes the successor broader than the value it replaces. Four 2019 groups are deprecated on that basis: the Perlecan and Aggrecan groups (merged into Proteoglycan core proteins disorders) and the Neonatal osteosclerotic dysplasias and Other sclerosing bone disorders groups (fused into Osteosclerotic disorders). Known gap: the exemplar disorders named in each description below were transcribed from Table 1 of the **2019** revision and have been renumbered and corrected only where the 2023 paper explicitly says a disorder moved (e.g. trichorhinophalangeal dysplasia out of the acromelic group). They are illustrative, not the full membership of a group, and a full re-transcription against the 2023 table (774 rows, extracted and available) is outstanding. The same caveat applies to the per-entry assignments: the bulk of them were derived from the 2019 table and carry 2019 provenance in their ``notes``. That re-verification is tracked in monarch-initiative/dismech#7867, which also records the groups with no dismech coverage at all - including the new 2023 group 28 (parathyroid hormone signaling cascade), whose six disorders (Jansen and Csukasi-Krakow metaphyseal dysplasia, Blomstrand dysplasia, Eiken dysplasia, PTHLH brachydactyly and osteolysis) are simply not yet curated. MONDO mapping policy. No group carries a ``meaning:`` — that would assert the value *is* an ontology class, which is never quite true for a curated nosology group. Where a MONDO class denotes the same disease family it is recorded as ``close_mappings:`` instead, under a deliberately high bar: a candidate is rejected if the MONDO class contains any entity the Nosology itself lists in a *different* group, since such a mapping would silently contradict the committee's own placement. Three of the groups qualify, all gene-defined series that nest cleanly inside one group: - FGFR3 chondrodysplasias → MONDO:0019685 FGFR3-related chondrodysplasia. Contains exactly the group's members and, importantly, excludes the FGFR3 craniosynostoses (Muenke, Crouzon with acanthosis nigricans), which the nosology places in the craniosynostosis group. - TRPV4 disorders → MONDO:0018240 TRPV4-related bone disorder. - Acromesomelic dysplasias → MONDO:0019696 acromesomelic dysplasia. Rejected candidates, recorded so they are not re-proposed: MONDO:0022800 type 2 collagenopathy (contains spondylometaphyseal dysplasia 'corner fracture' type, listed in the SMD group); MONDO:0019695 acromelic dysplasia (contains the trichorhinophalangeal syndromes and Langer-Giedion, which the 2023 revision moved to group 19, plus terminal osseous dysplasia in group 6 and short-rib thoracic dysplasia 9 in the ciliopathy group — note the earlier rationale citing pseudohypoparathyroidism type 1A no longer applies, since the 2023 revision renamed that entity Albright hereditary osteodystrophy and placed it inside group 17; the class still straddles on the other three); MONDO:0017198 osteopetrosis (contains melorheostosis and osteopathia striata with cranial sclerosis, which belong to the osteosclerotic group); MONDO:0015338 syndromic craniosynostosis (contains cranioectodermal dysplasia, a skeletal ciliopathy). Several groups have no usable class at all — either the nearest MONDO term is obsolete (chondrodysplasia punctata) or it is *narrower* than the group, which mixes in entities falling outside it. In every mapped case MONDO remains broader than the group, since the nosology lists only entities meeting its inclusion criteria; that is why the relation is ``close_mappings`` and not ``exact_mappings``.