SECISBP2 deficiency is an autosomal recessive inborn error of selenoprotein synthesis caused by biallelic SECISBP2 variants. SECISBP2/SBP2 is part of the SECIS-recognition machinery that recodes UGA codons for selenocysteine insertion, so partial loss of function reduces synthesis of many human selenoproteins. The downstream pathograph includes impaired deiodinase-driven thyroid hormone metabolism, oxidative-stress vulnerability from antioxidant selenoprotein deficiency, growth failure with delayed bone maturation, and variable neurodevelopmental involvement.
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name: SECISBP2 Deficiency
creation_date: "2026-07-06T05:15:58Z"
category: Metabolic Disorder
parents:
- Selenoprotein Biosynthesis Disorder
- Trace Element Metabolism Disorder
description: >-
SECISBP2 deficiency is an autosomal recessive inborn error of selenoprotein
synthesis caused by biallelic SECISBP2 variants. SECISBP2/SBP2 is part of
the SECIS-recognition machinery that recodes UGA codons for selenocysteine
insertion, so partial loss of function reduces synthesis of many human
selenoproteins. The downstream pathograph includes impaired deiodinase-driven
thyroid hormone metabolism, oxidative-stress vulnerability from antioxidant
selenoprotein deficiency, growth failure with delayed bone maturation, and
variable neurodevelopmental involvement.
synonyms:
- selenocysteine insertion sequence-binding protein 2 deficiency
- SBP2 deficiency
- SECISBP2-related multisystem selenoprotein deficiency
notes: >-
WP-079 seed identifiers: OMIM:609698 and ORPHA:171706. No exact local MONDO
disease term was resolved, so disease_term is intentionally left unbound.
external_assertions:
- name: OMIM SECISBP2 deficiency record
source: OMIM
assertion_type: disease_record
external_id: OMIM:609698
url: https://omim.org/entry/609698
description: OMIM phenotype record corresponding to SECISBP2 deficiency.
- name: Orphanet SECISBP2 deficiency record
source: Orphanet
assertion_type: structured_disease_record
external_id: ORPHA:171706
url: http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=171706
description: Orphanet structured disease record corresponding to SECISBP2 deficiency.
classifications:
icimd_category:
- classification_value: trace_element_other
notes: >-
ICIMD category 22, "Disorders of trace elements and metals", other
trace-element metabolism. SECISBP2 deficiency disrupts the use of
selenium as selenocysteine in human selenoproteins.
evidence:
- reference: PMID:21084748
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Selenium, a trace element that is fundamental to human health, is
incorporated into some proteins as selenocysteine (Sec), generating a
family of selenoproteins.
explanation: >-
Supports classification under trace-element metabolism through impaired
selenium incorporation into selenoproteins.
inheritance:
- name: Autosomal Recessive
inheritance_term:
preferred_term: Autosomal recessive inheritance
term:
id: HP:0000007
label: Autosomal recessive inheritance
evidence:
- reference: PMID:16228000
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Systematic linkage analysis of genes involved in DIO2 synthesis and
degradation led to the identification of an inherited Sec incorporation
defect, caused by a homozygous missense mutation in SECISBP2 (also called
SBP2).
explanation: >-
The originally described family had a homozygous SECISBP2 variant causing
the Sec incorporation defect.
- reference: PMID:21084748
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Here, we describe subjects with compound heterozygous defects in the
SECISBP2 gene.
explanation: >-
Compound heterozygosity in affected subjects supports recessive
inheritance.
genetic:
- name: SECISBP2 pathogenic variants
gene_term:
preferred_term: SECISBP2
term:
id: hgnc:30972
label: SECISBP2
association: Loss-of-function
presence: Positive
notes: >-
Reported homozygous and compound heterozygous SECISBP2 variants impair the
SECIS-binding protein required for selenocysteine insertion. Residual
activity is consistent with survival and variable multisystem severity.
evidence:
- reference: PMID:16228000
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
An unrelated child with a similar phenotype was compound heterozygous
with respect to mutations in SECISBP2.
explanation: >-
Supports SECISBP2 as the causal disease gene in an independent affected
child.
- reference: PMID:22247018
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The patient showed typical symptoms of SBP2 deficiency, and novel compound
heterozygous mutations were identified in SBP2 (p.M515fsX563/p.Q79X).
explanation: >-
Supports additional pathogenic SECISBP2/SBP2 variant classes in affected
individuals.
pathophysiology:
- name: SECISBP2-dependent Sec incorporation defect
description: >-
SECISBP2/SBP2 loss impairs SECIS-mediated recoding of UGA as
selenocysteine, creating a proximal defect in selenocysteine incorporation
during translation.
genes:
- preferred_term: SECISBP2
term:
id: hgnc:30972
label: SECISBP2
biological_processes:
- preferred_term: selenocysteine incorporation
term:
id: GO:0001514
label: selenocysteine incorporation
modifier: DECREASED
chemical_entities:
- preferred_term: selenocysteine
term:
id: CHEBI:9093
label: selenocysteine
evidence:
- reference: PMID:16228000
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Systematic linkage analysis of genes involved in DIO2 synthesis and
degradation led to the identification of an inherited Sec incorporation
defect, caused by a homozygous missense mutation in SECISBP2 (also called
SBP2).
explanation: >-
Directly identifies the proximal disease mechanism as an inherited
SECISBP2-mediated selenocysteine incorporation defect.
downstream:
- target: Reduced selenoprotein synthesis
description: >-
Failed SECISBP2-dependent Sec incorporation reduces synthesis of multiple
human selenoproteins.
causal_link_type: DIRECT
evidence:
- reference: PMID:21084748
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
These individuals have reduced synthesis of most of the 25 known human
selenoproteins, resulting in a complex phenotype.
explanation: >-
Supports reduced selenoprotein synthesis downstream of SECISBP2 defects.
- name: Reduced selenoprotein synthesis
description: >-
Decreased Sec insertion reduces synthesis of multiple selenoproteins,
including deiodinases and antioxidant enzymes, creating a multisystem
selenoprotein deficiency state.
biological_processes:
- preferred_term: selenocysteine incorporation
term:
id: GO:0001514
label: selenocysteine incorporation
modifier: DECREASED
chemical_entities:
- preferred_term: selenocysteine
term:
id: CHEBI:9093
label: selenocysteine
evidence:
- reference: PMID:21084748
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
These individuals have reduced synthesis of most of the 25 known human
selenoproteins, resulting in a complex phenotype.
explanation: >-
Establishes the generalized selenoprotein synthesis defect.
downstream:
- target: Impaired thyroid hormone metabolism
description: >-
Reduced synthesis of deiodinase selenoproteins disrupts thyroid hormone
activation and inactivation.
causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
evidence:
- reference: PMID:39315526
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Defects in the gene encoding selenocysteine insertion sequence binding
protein 2, SECISBP2, result in global impaired selenoprotein synthesis
manifesting a complex syndrome with characteristic serum thyroid
function tests due to impaired thyroid hormone metabolism.
explanation: >-
Links impaired selenoprotein synthesis to thyroid hormone metabolism
abnormalities in SECISBP2 deficiency.
- target: Oxidative-stress vulnerability
description: >-
Deficiency of antioxidant selenoproteins increases cellular reactive
oxygen species and stress sensitivity.
causal_link_type: DIRECT
evidence:
- reference: PMID:21084748
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Cutaneous deficiencies of antioxidant selenoenzymes, increased cellular
ROS, and susceptibility to ultraviolet radiation-induced oxidative
damage may mediate the observed photosensitivity.
explanation: >-
Supports antioxidant selenoenzyme deficiency and increased ROS as a
downstream cellular dysfunction.
- name: Impaired thyroid hormone metabolism
description: >-
Deiodinases are selenoproteins required for thyroid hormone metabolism.
Their reduced activity produces the characteristic abnormal thyroid
function tests observed in SECISBP2 deficiency.
biological_processes:
- preferred_term: thyroid hormone metabolic process
term:
id: GO:0042403
label: thyroid hormone metabolic process
modifier: DECREASED
locations:
- preferred_term: endocrine system
term:
id: UBERON:0000949
label: endocrine system
evidence:
- reference: PMID:16228000
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Deiodinases (DIOs) are selenoproteins involved in thyroid hormone
metabolism.
explanation: >-
Supports the mechanistic bridge from reduced selenoprotein synthesis to
thyroid hormone metabolism abnormalities.
- name: Oxidative-stress vulnerability
description: >-
Loss of antioxidant selenoprotein capacity increases cellular reactive
oxygen species and vulnerability to oxidative injury.
biological_processes:
- preferred_term: response to oxidative stress
term:
id: GO:0006979
label: response to oxidative stress
modifier: INCREASED
cell_types:
- preferred_term: fibroblast
term:
id: CL:0000057
label: fibroblast
evidence:
- reference: PMID:21084748
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Cutaneous deficiencies of antioxidant selenoenzymes, increased cellular
ROS, and susceptibility to ultraviolet radiation-induced oxidative damage
may mediate the observed photosensitivity.
explanation: >-
Supports increased ROS and oxidative stress susceptibility in SECISBP2
deficiency.
phenotypes:
- name: Abnormal thyroid physiology
description: >-
SECISBP2 deficiency produces abnormal thyroid hormone metabolism and
characteristic thyroid function tests.
phenotype_term:
preferred_term: Abnormality of thyroid physiology
term:
id: HP:0002926
label: Abnormality of thyroid physiology
evidence:
- reference: PMID:16228000
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
We identified three of seven siblings with clinical evidence of abnormal
thyroid hormone metabolism.
explanation: >-
Supports abnormal thyroid hormone metabolism as a clinical phenotype.
- name: Short stature
description: >-
Growth failure is part of the multisystem presentation.
phenotype_term:
preferred_term: Short stature
term:
id: HP:0004322
label: Short stature
evidence:
- reference: PMID:39315526
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Genetic and laboratory investigations were performed in affected members
from 6 families presenting with short stature and failure to thrive.
explanation: >-
Supports short stature in affected SECISBP2 deficiency families.
- name: Failure to thrive
description: >-
Failure to thrive accompanies growth impairment in multiple reported
SECISBP2 deficiency families.
phenotype_term:
preferred_term: Failure to thrive
term:
id: HP:0001508
label: Failure to thrive
evidence:
- reference: PMID:39315526
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Genetic and laboratory investigations were performed in affected members
from 6 families presenting with short stature and failure to thrive.
explanation: >-
Supports failure to thrive in SECISBP2 deficiency.
- name: Delayed skeletal maturation
description: >-
Delayed bone maturation has been reported with SECISBP2/SBP2 deficiency,
consistent with impaired thyroid hormone action at the growth plate.
phenotype_term:
preferred_term: Delayed skeletal maturation
term:
id: HP:0002750
label: Delayed skeletal maturation
evidence:
- reference: PMID:22247018
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
A Japanese boy presented with unusual thyroid function tests (normal or
slightly elevated TSH, low-normal or slightly decreased free T(3) (FT(3)),
and elevated free thyroxine (FT(4))), short stature without GH deficiency,
and delayed bone maturation.
explanation: >-
Directly supports delayed bone maturation in an SBP2/SECISBP2 deficiency
patient.
- name: Neurodevelopmental involvement
description: >-
Some affected individuals have complex neurodevelopmental involvement,
including speech and intellectual impairment and seizures.
phenotype_term:
preferred_term: Intellectual disability
term:
id: HP:0001249
label: Intellectual disability
evidence:
- reference: PMID:39315526
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Thyroid hormone treatment improved motor development, whereas speech and
intellectual impairments persisted.
explanation: >-
Supports persistent intellectual and speech impairment as part of the
neurodevelopmental phenotype.
- name: Seizure
description: >-
Seizures are part of the reported neurodevelopmental presentation in some
SECISBP2 deficiency probands.
phenotype_term:
preferred_term: Seizure
term:
id: HP:0001250
label: Seizure
evidence:
- reference: PMID:39315526
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Four probands presented a complex neurodevelopmental profile, including
absent speech, autistic features, and seizures.
explanation: >-
Supports seizures in SECISBP2 deficiency.