Complex lethal osteochondrodysplasia

Summary

Complex lethal osteochondrodysplasia (MONDO:0014821) is a disease caused by TAPT1 (GenCC Strong), with 1 cohort gene.

At a glance

• Prevalence: <1 / 1 000 000 (Worldwide) [Orphanet-validated]
• Causal gene: TAPT1 (GenCC Strong)
• Cohort genes: 1
• ClinVar variants: 10

Clinical features

Epidemiology

Prevalence records

2 prevalence record(s), Orphanet:

Type	Class	Value	Geography	Validation
Cases/families		6	Worldwide	Validated
Point prevalence	<1 / 1 000 000		Worldwide	Validated

Identifiers

Disease identifiers

Field	Value
Canonical name	complex lethal osteochondrodysplasia
Mondo ID	MONDO:0014821
OMIM	616897
Orphanet	457378
UMLS	C4225162
MedGen	900688
GARD	0017807
Is cancer (heuristic)	no

Also known as: Complex lethal osteochondrodysplasia, Symoens-Barnes-Gistelinck type · OCLSBG

Data availability: 10 ClinVar variants · 4 GenCC gene-disease records.

Disease family

Classification path: disease › human disease › disease by etiologic mechanism › disease of genetic or genomic mechanism › hereditary disease › skeletal dysplasia › complex lethal osteochondrodysplasia

Related subtypes (118): osteochondrodysplasia, diaphyseal medullary stenosis-bone malignancy syndrome, fibular aplasia-ectrodactyly syndrome, cerebrocostomandibular syndrome, cleidorhizomelic syndrome, dyschondrosteosis-nephritis syndrome, dysplasia epiphysealis hemimelica, carpotarsal osteochondromatosis, Camurati-Engelmann disease, genochondromatosis, autosomal dominant osteosclerosis, Worth type, coxopodopatellar syndrome, Lenz-Majewski hyperostotic dwarfism, delayed membranous cranial ossification, metaphyseal dysplasia-maxillary hypoplasia-brachydacty syndrome, oculodentodigital dysplasia, Ollier disease, osteoglophonic dysplasia, parietal foramina with cleidocranial dysplasia, chondromalacia patellae, Currarino triad, Proteus syndrome, brachydactyly-elbow wrist dysplasia syndrome, tricho-dento-osseous syndrome, bird headed-dwarfism, Montreal type, Yunis-Varon syndrome, split hand-foot malformation 1 with sensorineural hearing loss, ghosal hematodiaphyseal dysplasia, hyperostosis corticalis generalisata, Larsen-like syndrome, B3GAT3 type, mesomelic dwarfism-cleft palate-camptodactyly syndrome, metaphyseal acroscyphodysplasia, metaphyseal dysostosis-intellectual disability-conductive deafness syndrome, familial osteodysplasia, Anderson type, pseudodiastrophic dysplasia, rhizomelic syndrome, Urbach type, Richieri Costa-Pereira syndrome, craniometadiaphyseal dysplasia, wormian bone type, Weaver syndrome, SHOX-related short stature, craniofrontonasal syndrome, Eiken syndrome, 2q37 microdeletion syndrome, skeletal dysplasia-epilepsy-short stature syndrome, rhizomelic dysplasia, Patterson-Lowry type, pelvic dysplasia-arthrogryposis of lower limbs syndrome, Marshall-Smith syndrome, baby rattle pelvis dysplasia, metaphyseal dysplasia, Braun-Tinschert type, genitopatellar syndrome, osteofibrous dysplasia, Larsen-like osseous dysplasia-short stature syndrome, pancreatic insufficiency-anemia-hyperostosis syndrome, microcephalic primordial dwarfism due to ZNF335 deficiency, Hartsfield-Bixler-Demyer syndrome, colobomatous microphthalmia-rhizomelic dysplasia syndrome, Tatton-Brown-Rahman overgrowth syndrome, tall stature-scoliosis-macrodactyly of the great toes syndrome, Catel-Manzke syndrome, cognitive impairment - coarse facies - heart defects - obesity - pulmonary involvement - short stature - skeletal dysplasia syndrome, skeletal overgrowth-craniofacial dysmorphism-hyperelastic skin-white matter lesions syndrome, amniotic band syndrome, metaphyseal anadysplasia, syndromic craniosynostosis, thin ribs-tubular bones-dysmorphism syndrome, dysplasia of head of femur, Meyer type, epimetaphyseal skeletal dysplasia, melorheostosis with osteopoikilosis, Cole-Carpenter syndrome, spondylometaphyseal dysplasia, omodysplasia, Bruck syndrome, osteopetrosis, congenital absence of upper arm and forearm with hand present, congenital absence of thigh and lower leg with foot present, congenital absence of both forearm and hand, congenital absence of both lower leg and foot, acheiria, apodia, chondroectodermal dysplasia with night blindness, TRPV4-related bone disorder, adactyly of foot, short stature-advanced bone age-early-onset osteoarthritis syndrome, McCune-Albright syndrome, parietal foramina, Sotos syndrome, dysspondyloenchondromatosis, autosomal recessive cutis laxa type 2, FGFR3-related chondrodysplasia, filamin-related bone disorder, short rib dysplasia, spondylodysplastic dysplasia, acromelic dysplasia, bent bone dysplasia, chondrodysplasia punctata, primary osteolysis, non-syndromic limb reduction defect, Robinow syndrome, synpolydactyly, acrocoxomesomelic dysplasia, bone dysplasia Moore type, bone dysplasia corpus callosum agenesis, type 2 collagenopathy, LRP5-related primary osteoporosis, SLC26A2-related skeletal dysplasia, COMP-related skeletal dysplasia, primordial dwarfism and slender bone disorder, polydactyly-syndactyly-triphalangism, lysosomal storage disease with skeletal involvement, abnormal mineralization disorder, calvarial doughnut lesions with bone fragility and spondylometaphyseal dysplasia, de la Chapelle dysplasia, mesomelic dysplasia-digital anomalies-intellectual disability syndrome, proximal femoral focal deficiency, rhizomelic dysplasia, Ain-Naz type, craniotubular dysplasia, Ikegawa type, TRIP11-related skeletal dysplasia, FAM111A-related skeletal dysplasia

Genetics & variants

GWAS landscape

No GWAS associations recorded — common-variant (GWAS) studies don’t cover this disease (typical for Mendelian / rare diseases). See the curated gene cohort and Mendelian overlap below.

Variant details and genetic-evidence tiers

ClinVar germline variants

10 retrieved; paginated sample, class counts are floors:

4 uncertain significance, 3 pathogenic, 1 benign/likely benign, 1 likely pathogenic, 1 benign

ClinVar	Variant (HGVS)	Gene	Classification	Review
224906	NM_153365.3(TAPT1):c.1108-1G>C	TAPT1	Pathogenic	no assertion criteria provided
224907	NM_153365.3(TAPT1):c.1058A>T (p.Asp353Val)	TAPT1	Pathogenic	no assertion criteria provided
3362631	NM_153365.3(TAPT1):c.846+2T>A	TAPT1	Pathogenic	criteria provided, single submitter
1252088	NM_153365.3(TAPT1):c.1156C>T (p.Arg386Ter)	TAPT1	Likely pathogenic	criteria provided, single submitter
1991752	NM_153365.3(TAPT1):c.70G>A (p.Asp24Asn)	LOC129992296	Uncertain significance	criteria provided, multiple submitters, no conflicts
1522735	NM_153365.3(TAPT1):c.1499C>T (p.Ser500Phe)	TAPT1	Uncertain significance	criteria provided, multiple submitters, no conflicts
3068159	NM_153365.3(TAPT1):c.1673G>A (p.Arg558Lys)	TAPT1	Uncertain significance	criteria provided, single submitter
690289	NM_153365.3(TAPT1):c.1032G>T (p.Met344Ile)	TAPT1	Uncertain significance	criteria provided, multiple submitters, no conflicts
1212785	NM_153365.3(TAPT1):c.137T>G (p.Leu46Arg)	TAPT1	Benign/Likely benign	criteria provided, multiple submitters, no conflicts
1261045	NM_153365.3(TAPT1):c.200-16A>C	TAPT1	Benign	criteria provided, multiple submitters, no conflicts

Genes & proteins

Mendelian disease overlap and somatic drivers

GenCC: 5 · Orphanet: 1 · OMIM-shared: 0 · Dual-evidence (GWAS+Mendelian): 0

GenCC gene–disease validity (cohort genes)

the Disease column is the GenCC-asserted condition — a cohort gene’s strongest validity may be for a related predisposition syndrome.

Gene	Classification	Inheritance	Disease	Records
TAPT1	Strong	Autosomal recessive	complex lethal osteochondrodysplasia	5

Orphanet rare-disease linkage (cohort genes)

Gene	Orphanet ID	Rare disease
TAPT1	Orphanet:457378	Complex lethal osteochondrodysplasia

Cohort genes → proteins

1 cohort genes, 1 distinct canonical proteins.

Evidence partition

Subset	Genes
multi_evidence	1

Cohort genes (full)

Symbol	HGNC	Ensembl	UniProt	Name	Evidence
TAPT1	HGNC:26887	ENSG00000169762	Q6NXT6	Transmembrane anterior posterior transformation protein 1 homolog	gencc,clinvar

Cohort function summary

Lead sentence per gene, UniProt-curated.

Symbol	Protein name	Function (lead sentence)
TAPT1	Transmembrane anterior posterior transformation protein 1 homolog	Plays a role in primary cilia formation.

Protein-family classification

Druggable: 0 · Difficult: 0 · Unknown: 1 · Druggable fraction: 0.0

Family distribution

Cohort families vs a genome-wide background (hypergeometric, BH-FDR; fold = observed/expected). Counts kept; sorted by enrichment, so the catch-all Other/Unknown bucket no longer leads.

Family	Genes	Fold	FDR
Other/Unknown	1	1.8×	0.558

Per-gene assignment

Symbol	Family	Druggable?	EC	InterPro (top 3)
TAPT1	Other/Unknown	no		Tatp1

Expression context

Cohort genes with no expression data: 0.

1 cohort gene are a single-cell marker in ≥1 SCXA experiment.

Breadth distribution (Bgee present_calls)

Bucket	Genes
narrow (1-5 tissues)	0
moderate (6-20)	0
broad (>20)	1
unknown	0

Top tissues across cohort

Tissue	Cohort genes
endothelial cell	1
oocyte	1
secondary oocyte	1

Per-gene tissue summary (top 30)

Symbol	Bgee breadth	FANTOM5 breadth	SCXA	Top tissues
TAPT1	266	ubiquitous	marker	secondary oocyte, endothelial cell, oocyte

Protein interactions among cohort

Intra-cohort edges: 0.

Hub genes (top 10 by interactor count)

Symbol	Interactor count
TAPT1	884

Structural data

PDB: 0 · AlphaFold-only: 1 · No structure: 0

AlphaFold-only cohort genes (top 30 by pLDDT)

Symbol	UniProt	pLDDT
TAPT1	Q6NXT6	71.98

Function

Pathway analysis

Distinct Reactome pathways touched by cohort: 0. Enrichment computed across 1 evidence-associated genes (0 with Reactome annotation).

GO biological processes by enrichment

Over-representation of cohort genes vs the genome-wide background (hypergeometric test, Benjamini-Hochberg FDR; fold = observed/expected over 1 annotated cohort genes). Counts and members are kept as ground-truth; sorted by enrichment.

GO term	Cohort genes	Fold	FDR	Sample cohort genes
positive regulation of bone development	1	5617.3×	0.001	TAPT1
positive regulation of cartilage development	1	936.2×	0.003	TAPT1
neural crest cell development	1	802.5×	0.003	TAPT1
positive regulation of cilium assembly	1	766.0×	0.003	TAPT1
embryonic skeletal system development	1	391.9×	0.004	TAPT1
cell projection organization	1	374.5×	0.004	TAPT1
cartilage development	1	251.5×	0.004	TAPT1
ossification	1	227.7×	0.004	TAPT1

Therapeutics

Drug target analysis

Approved (phase 4): 0 · Phase ≥3: 0 · Phased (≥1): 0 · Undrugged: 1

Druggability breadth: 0 of 1 evidence-associated genes (0%) have a ChEMBL target (buckets above are over the deeply-mined display cohort).

Top cohort targets by molecule count

Symbol	Molecules	Max phase
TAPT1	0	0

Bioactivity and enzyme data

Enzyme cohort genes (≥1 EC): 0.

Pharmacogenomics

Cohort genes with a PharmGKB record: 1; with CPIC/DPWG dosing guidelines: 0.

No cohort gene has a CPIC/DPWG genotype-guided dosing guideline (PharmGKB).

Chemical tractability of cohort targets

0 approved/phased compounds have measured bioactivity against a cohort gene (and aren’t yet in disease-level trials). This is a research / tractability signal, NOT a therapeutic recommendation — a bioactivity row often reflects off-target or screening binding (e.g. promiscuous kinase inhibitors against a cohort kinase), implying no disease mechanism.

Druggability pyramid

Cohort genes binned by druggability tier (high → low):

Tier	Definition	Genes	Symbols
A	Approved (phase 4 drug)	0
B	Phased (≥1) drug, not yet approved	0
C	Druggable family + PDB, no drug	0
D	Druggable family + AlphaFold only, no drug	0
E	Difficult family or no structure, no drug	1	TAPT1

Undrugged target profiles

1 cohort genes are undrugged. Ranked by ‘starting-point quality’ (assay depth + drugged-partner adjacency).

Symbol	ChEMBL assays	Drugged partners (top 3)
TAPT1	0	—

Clinical trials & evidence

Clinical trials

Clinical trials: 0.