Pica — Comprehensive Research Report

1. Disease Information

Overview. Pica is a feeding and eating disorder defined by the persistent eating of nonnutritive, nonfood substances that is developmentally inappropriate, not part of a culturally sanctioned practice, and — when it co-occurs with another mental or medical condition — severe enough to independently warrant clinical attention. Commonly ingested substances include earth/clay (geophagia), ice (pagophagia), starch (amylophagia), paper (xylophagia), hair (trichophagia), feces (coprophagia), chalk, soap, ash, paint chips, and metal objects.

Key identifiers: - MONDO: MONDO:0001441 (per Mondo Disease Ontology; cross-referenced across OMIM, Orphanet, MeSH, NCIt) (Mondo Disease Ontology) - DSM-5-TR: Feeding and Eating Disorders chapter; criteria require persistent nonnutritive/nonfood ingestion for ≥1 month, developmentally inappropriate, not culturally sanctioned, and clinically significant if comorbid with another condition — some clinical sources suggest requiring a minimum duration of 2 years for definitive diagnosis in some settings (DSM-5-TR Update) - ICD-11: A single unified code (no longer split by age, unlike ICD-10) - ICD-10-CM: F98.3 (children/adolescents), F50.8 (previously) / effective Oct 1, 2024, F50.83 for adults (StatPearls) - MeSH: D010842 "Pica"

Synonyms/subtypes: geophagia/geophagy (clay/soil), pagophagia (ice), amylophagia (starch), xylophagia (wood/paper), trichophagia (hair), coprophagia (feces), lithophagia (stones), plumbophagia (paint/lead objects).

Evidence base: Information is derived from a mix of case reports/series, cross-sectional surveys (largely in pregnant women and children with developmental disabilities), a small number of population-based cohort studies, and disease/behavioral registries — there is comparatively little large-scale EHR-based epidemiology, and no dedicated national disease registry.

2. Etiology

Disease causal factors: Pica does not have a single unifying cause; it is best modeled as a convergent behavioral endpoint reached via several overlapping causal routes: 1. Nutritional deficiency-driven (iron, and to a lesser extent zinc) — the best-supported mechanistic route 2. Neurodevelopmental — high co-occurrence with autism spectrum disorder (ASD) and intellectual disability (ID), often as a form of self-stimulatory/automatically-reinforced behavior 3. Physiological/gravid state — pregnancy-associated pica, possibly linked to nausea and cultural practice 4. Psychiatric — reported in obsessive-compulsive spectrum conditions, schizophrenia, and in the context of severe psychosocial deprivation 5. Culturally sanctioned geophagia that becomes classified as pathological only when it causes harm or exceeds a normative threshold

Genetic risk factors: There is no known single causal gene or Mendelian etiology for pica as an isolated disorder. Pica is, however, a recognized behavioral feature of several genetic neurodevelopmental syndromes: - Smith-Magenis syndrome (RAI1 gene, 17p11.2 deletion/mutation) — food-related problem behaviors, including pica, are reported at levels comparable to or exceeding Prader-Willi syndrome ("For food preoccupation, Smith-Magenis syndrome adults scored higher (8.6 ± 3.4) compared to Prader-Willi syndrome adults (8.1 ± 2.0)") - Prader-Willi syndrome (15q11-q13 paternal deletion/UPD; MAGEL2) — pica reported, notably exacerbated during comorbid Kleine-Levin-type hypersomnia episodes: "During hypersomnia episodes... the patient exhibited exacerbated hyperphagia, pica, poor emotional control, stereotyped speech and agitated behavior upon awakening" (PMID:8650457) - Broader ASD/ID genetic etiologies (fragile X, Rett syndrome, etc.) confer elevated pica risk indirectly through the ID/ASD phenotype rather than a pica-specific mechanism

Environmental/demographic risk factors: - Iron deficiency anemia (strongest and most reversible risk factor) - Zinc deficiency - Pregnancy, particularly third trimester, and pregnancy-associated nausea (aOR 3.60 for third trimester; aOR 2.11 for nausea; PMID:34252052) - Lower socioeconomic status, food insecurity, malnutrition - Childhood age (peak prevalence in toddlers/preschoolers) - Female sex (some adolescent studies) and lower paternal education - End-stage chronic kidney disease / hemodialysis - Sickle cell disease - Psychosocial deprivation, institutionalization, limited parental supervision - Cultural transmission (geophagia is normative in parts of sub-Saharan Africa; prevalence estimates in pregnancy range "from 0.007% in Denmark to 92.5% in Nigeria")

Protective factors: - Adequate iron/zinc nutritional status - Iron repletion is both a protective and therapeutic intervention — a scoping review of 20 studies found "identification of pica symptoms allowed treatment for iron deficiency and led to resolution of all symptoms in all 20 articles" (PMID:37220446) - Structured behavioral supports in individuals with ASD/ID (differential reinforcement, environmental enrichment)

Gene-environment interaction: The clearest interaction model is genetic vulnerability to neurodevelopmental disability (ASD/ID) combined with an environmental/behavioral reinforcement pathway (automatic sensory reinforcement from oral exploration), compounded in some cases by superimposed micronutrient deficiency. No formal GWAS or CTD gene-environment interaction datasets specific to pica were identified.

3. Phenotypes

Suggested HPO terms and characteristics:

Onset: Typically emerges in early childhood (18 months–6 years is developmentally normal mouthing; pathological pica is diagnosed only beyond the developmentally appropriate window, generally after age 2). Also arises de novo in pregnancy (often 2nd–3rd trimester) and can appear at any age in the context of ID/ASD, psychiatric illness, or acquired nutritional deficiency (e.g., post-bariatric surgery, dialysis).

Severity/progression: Highly variable — from mild, self-limited toddler pica that resolves spontaneously, to severe, chronic, treatment-refractory pica in individuals with profound ID/ASD requiring lifelong behavioral management. Course can be episodic (pregnancy-limited) or persistent/progressive (in ASD/ID populations, where recurrence across developmental waves is common — "19.55% reported pica at least at two waves" in the ALSPAC cohort).

Frequency in general population: General-population prevalence estimates range from about 3.5%–5% in children (DSM-5 cites ~5% in school-age children), with a peak around 36 months (~2.29% in one large birth cohort) declining thereafter.

Quality of life impact: Direct QoL instruments specific to pica are lacking; impact is inferred from complication burden (GI obstruction, lead neurotoxicity, parasitic disease, social stigma, caregiver burden in ASD/ID populations, and interference with renal replacement therapy adherence in CKD).

4. Genetic/Molecular Information

Pica as an isolated entity is not a monogenic disease — there are no OMIM-cataloged "Pica" causal genes, no ClinVar pathogenic-variant entries specific to pica, and no dedicated GWAS Catalog hits. Genetic contribution is indirect, mediated through: - Syndromic ID/ASD genes (e.g., RAI1 [HGNC:9857] in Smith-Magenis syndrome; MAGEL2 [HGNC:6814] and the 15q11-q13 imprinted locus in Prader-Willi syndrome) - Possible heritable contribution to iron-handling/anemia susceptibility (e.g., variants affecting iron absorption), though no pica-specific variant has been established

Epigenetics: No pica-specific epigenetic studies identified; Prader-Willi syndrome's imprinting mechanism is relevant only insofar as it explains the syndromic food-related behavior phenotype, not pica specifically.

Chromosomal abnormalities: None specific to pica; relevant only via the syndromic ID conditions above (15q11-q13 deletion/UPD for PWS; 17p11.2 deletion for Smith-Magenis).

5. Environmental Information

• Toxin exposure: Lead-based paint and contaminated soil are the dominant environmental hazards — "Children eating paint chips from pre-1978 homes can accumulate lead levels that damage the developing nervous system, impair cognition, and cause behavioral problems that persist for years."
• Geophagic clay contamination: Toxic metals (arsenic, cadmium, lead) have been documented in clay consumed as pica by pregnant women in Ghana (PMC7071753), raising heavy-metal exposure risk.
• Infectious agents: Geophagia is a recognized route for soil-transmitted helminth infection (Ascaris, Trichuris, hookworm) and exposure to bacteria/fungi/parasite ova in ingested soil.
• Lifestyle factors: Low socioeconomic status, food insecurity, and limited maternal education correlate with higher pica prevalence in several African antenatal cohorts.

6. Mechanism / Pathophysiology

Pathophysiology is incompletely understood and represents parallel, only partially overlapping causal chains rather than one pathway. The best-characterized causal chain:

Iron-deficiency route: Chronic iron deficiency (dietary insufficiency, GI blood loss, pregnancy-related iron demand, malabsorption) → reduced CNS iron availability (iron is a cofactor for tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis) → disrupted central dopaminergic neurotransmission → aberrant craving/reward-seeking behavior directed at nonnutritive substances → pica. Supporting review language: "The strong association of pica with iron deficiency anemia (IDA) lends credence to the hypothesis that dopamine transmission may be disrupted in this disorder... a common central pathway such as mediation by decreased CNS dopamine neurotransmission has been reported to be a specific result of iron deficiency" (PMID:35674869, The Neurology and Psychopathology of Pica).

A secondary, self-reinforcing loop exists for clay/kaolin-type pica: ingested clay binds free iron in the gut lumen ("adsorption of Fe2+ and Fe3+ to the negatively charged and large active surface area of kaolinite may lead to a reduction of available iron in the duodenum"), worsening the underlying deficiency — i.e., the coping behavior paradoxically deepens the causal deficiency.

Zinc-dopamine route: Zinc is a cofactor/modulator of the dopamine transporter (DAT), acting as "a potent non-competitive blocker of substrate translocation," and zinc deficiency is separately implicated in monoaminergic dysregulation (parallel literature in depression, PMC5337390), offering a second nutrient-neurotransmitter mechanistic arm converging on the same dopaminergic endpoint.

Neurodevelopmental/behavioral route (ASD/ID): In this population, pica is generally conceptualized not as a deficiency-driven craving but as a behavior maintained by automatic (sensory) reinforcement — oral/tactile sensory-seeking, similar to other stereotyped/self-stimulatory behavior, occurring independent of nutritional status. This is the dominant model in the applied-behavior-analysis literature: "Pica is a life-threatening form of challenging behavior displayed by individuals with intellectual and developmental disabilities and is typically maintained by automatic reinforcement."

Emesis/nausea-adaptive route (model-organism-derived hypothesis, translational to pregnancy-pica): In rats (a species incapable of vomiting), toxin/chemotherapy exposure induces kaolin consumption as a compensatory, adaptive behavior substituting for emesis: cisplatin/copper sulfate → activation of dopamine D2 receptors in the chemoreceptor trigger zone and 5-HT3 receptors on gastric vagal afferents → induction of pica/kaolin intake, blocked by ondansetron (5-HT3 antagonist) and other standard antiemetics. This has been proposed as informing the human pregnancy-nausea association (pica correlating with nausea, aOR 2.11), though direct human confirmation of this specific mechanism is lacking (a HUMAN_MODEL_MISMATCH-type gap).

Cell types/processes involved: Nigrostriatal and mesolimbic dopaminergic neurons (GO:0007212 dopamine receptor signaling pathway), area postrema/chemoreceptor trigger zone chemosensory neurons, vagal visceral afferents, enterocytes (iron/zinc absorption, duodenal mucosa).

GO term suggestions: GO:0007212 (dopamine receptor signaling pathway), GO:0006826 (iron ion transport), GO:0006829 (zinc ion transport), GO:0042493 (response to drug — antiemetic pharmacology context).

Tissue damage / biochemical abnormalities: Iron-deficiency erythropoiesis; possible lead-induced neurotoxicity from paint/soil pica; mucosal/GI mechanical injury from bezoar formation.

7. Anatomical Structures Affected

• Primary "organ" involved (behavioral origin): CNS — basal ganglia/striatal dopaminergic circuits, area postrema (UBERON:0002298 basal ganglia; UBERON:0002162 area postrema)
• Secondary/complication organs:
• GI tract (UBERON:0005409 stomach; UBERON:0002108 small intestine): bezoar formation (trichobezoar, lithobezoar/phytobezoar), obstruction, perforation, intussusception (Rapunzel syndrome)
• Hematologic system: iron-deficiency anemia
• Renal system: implicated bidirectionally in CKD/dialysis patients
• Dentition: abrasive wear/injury from hard substances
• Nervous system: lead neurotoxicity from paint/soil ingestion
• Cell types (Cell Ontology): enterocyte (CL:0000584), erythroid precursor cells, dopaminergic neuron (CL:0000700)
• Subcellular: mitochondrial/cytosolic tyrosine hydroxylase-dependent dopamine synthesis machinery; DAT (dopamine transporter) at presynaptic plasma membrane
• Laterality: Not applicable (systemic/behavioral).

8. Temporal Development

• Onset: Most commonly childhood (peak toddler/preschool, ~2–4 years), also common in the 2nd–3rd trimester of pregnancy, and can present at any age secondary to ID/ASD, psychiatric illness, or acquired systemic disease (CKD/dialysis, post-bariatric surgery).
• Progression: Variable — in typically developing children, largely self-limited and resolves with development; in ASD/ID and syndromic populations, tends to be chronic/persistent and can recur across developmental stages (ALSPAC cohort: recurrence at multiple assessment waves in ~20% of affected children).
• Course pattern: Episodic in pregnancy-associated cases (resolves post-partum in most); can be chronic/relapsing-remitting in ASD/ID and CKD-associated cases.
• Remission: Frequently spontaneous with age/development in young children; treatment-induced remission is well documented for iron-deficiency-associated pica (rapid resolution with iron repletion).
• Critical periods: Toddlerhood is a period where pica must be distinguished from normative developmental mouthing (hence DSM-5's developmental-inappropriateness criterion); third trimester of pregnancy is a recognized vulnerability window.

9. Inheritance and Population

• Prevalence: General pediatric population ~3.5%–5%; pregnancy/postpartum populations show an aggregated meta-analytic prevalence of 27.8% with substantial heterogeneity (0.007%–92.5% across countries) (Fawcett et al., Int J Gynaecol Obstet 2016;133(3):277-83, PMID:26892693); ASD populations 23.2% overall (28.1% with comorbid ID, 14.0% without ID) versus 8.4% in general developmental-delay populations and 3.5% in typically developing controls (Fields et al., Pediatrics 2021;147(2):e20200462, PMID:33408069).
• Inheritance pattern: Not a Mendelian trait; multifactorial/behavioral. Syndromic pica (Smith-Magenis, Prader-Willi) follows the inheritance pattern of the underlying syndrome (imprinting disorder / autosomal, typically de novo deletion).
• Sex ratio: Some adolescent-population studies show female predominance; pregnancy-associated pica is obviously female-specific by definition.
• Geographic distribution: Marked geographic variation, with geophagia most normalized/prevalent in sub-Saharan Africa (Nigeria up to 92.5% in some antenatal cohorts; Uganda 57% in one Kampala antenatal cohort, PMID:34252052) versus <1% in some Western cohorts (Denmark ~0.007%).
• Age distribution: Bimodal-ish clustering — early childhood peak and reproductive-age (pregnancy) peak, plus elevated rates in institutionalized/ID populations across the lifespan.

10. Diagnostics

• Laboratory tests: CBC, serum ferritin, serum iron/TIBC/transferrin saturation, zinc level, lead level (especially with paint/soil pica), stool ova and parasites (with geophagia), electrolytes (particularly relevant in CKD-associated pica).
• Biomarkers: Serum ferritin is the most sensitive/specific marker of iron deficiency in the absence of inflammation; must be interpreted alongside CRP given ferritin's acute-phase reactant behavior.
• Imaging: Abdominal X-ray/CT for suspected bezoar or radiopaque foreign material (especially with lithophagia/soil ingestion); used in complication workup rather than primary diagnosis.
• Endoscopy: For suspected gastric bezoar (trichobezoar, phytobezoar).
• Clinical criteria: DSM-5-TR (above); ICD-11 single code; differential diagnosis includes ARFID (Avoidant/Restrictive Food Intake Disorder — distinguished by lack of interest in food vs. specific craving for nonfood items), OCD, and culturally normative geophagia (excluded from diagnosis unless clinically harmful/excessive).
• Structured assessment instrument: PARDI (Pica, ARFID, and Rumination Disorder Interview) — a semi-structured, multi-informant clinical interview developed by Bryant-Waugh, Micali, Cooke, Lawson, Eddy, and Thomas (2018) to diagnose Pica, ARFID, and Rumination Disorder per DSM-5 criteria, with separate child and adult/young-person versions.
• Screening in special populations: No dedicated newborn/genetic screening exists; screening is opportunistic — iron studies in patients presenting with pica, and behavioral screening for pica in ASD/ID clinical intake protocols (e.g., Food-Related Problem Questionnaire, originally developed for Prader-Willi syndrome, also applied to Smith-Magenis syndrome).

11. Outcome/Prognosis

• Mortality: Direct mortality from pica itself is rare but can occur via severe complications (bowel perforation/peritonitis from bezoar, lead encephalopathy, severe parasitic disease, choking/airway obstruction from foreign objects).
• Morbidity: Primary morbidity burden comes from complications — iron-deficiency anemia, GI obstruction/bezoar (including Rapunzel syndrome causing "multiple sites of simultaneous intussusception"), dental injury, lead neurotoxicity with lasting cognitive/behavioral effects in children, and helminthic/parasitic infection from geophagia.
• Recovery potential: Excellent when driven by a reversible nutritional deficiency (iron/zinc repletion resolves symptoms in the large majority of reported cases) or when pregnancy-limited (typically resolves postpartum). Prognosis is more guarded/chronic in ASD/ID-associated and CKD-associated pica, where the underlying driver (neurodevelopmental disability, chronic renal failure) is not reversible.
• Prognostic factors: Presence/absence of reversible nutrient deficiency; presence of comorbid ASD/ID (associated with chronicity); severity/type of ingested material (hard/sharp/toxic objects carry higher complication risk); access to behavioral intervention.

12. Treatment

Pharmacotherapy / nutritional: - Iron supplementation — first-line when iron deficiency is identified; strongly supported ("treatment for iron deficiency... led to resolution of all symptoms in all 20 articles," PMID:37220446) - Zinc supplementation when zinc deficiency is documented - N-acetylcysteine (NAC) — a glutamatergic modulator with evidence in body-focused repetitive behaviors (trichotillomania, excoriation, onychophagia); mechanistically plausible but not directly evidence-based for pica/trichophagia specifically — an extrapolation from the related BFRB literature (PMID:35681955), representing a knowledge gap - Treatment of underlying psychiatric or renal disease as applicable

Behavioral interventions (primary treatment modality in ASD/ID populations): - Differential reinforcement of alternative behavior (DRA) - Response interruption and redirection (RIRD) - Response blocking / noncontingent reinforcement with competing stimuli - Preliminary evidence supports combined RIRD + DRA as effective; systematic reviews note the evidence base, while promising, remains limited in rigor and sample size (Moline et al., Clin Psychol Psychother 2021, PMID unlisted in search; McAdam et al. 2004)

Surgical/procedural: Endoscopic or surgical removal of bezoars; management of intestinal obstruction/perforation/intussusception (Rapunzel syndrome cases).

Supportive care: Environmental modification (removing access to hazardous nonfood items, especially lead paint remediation), nutritional counseling, caregiver education and supervision strategies.

Suggested MAXO terms: - MAXO:0000088 (dietary intervention) — for iron/zinc repletion - MAXO:0000011 (physical therapy) — not typically applicable - MAXO:0000079 (genetic counseling) — for syndromic cases (Smith-Magenis, Prader-Willi) - MAXO:0000950 (supportive care) - A specific "applied behavior analysis" / DRA MAXO term should be verified via OAK search (uv run runoak -i sqlite:obo:maxo search "behavioral intervention") — not confirmed in this research pass

Experimental treatments: No dedicated registered clinical trials targeting pica as a primary endpoint were identified in this search; most trial-registry data intersects only tangentially (e.g., iron-deficiency treatment trials that report pica as a secondary outcome).

13. Prevention

• Primary prevention: Adequate maternal/childhood iron and zinc nutrition; lead-paint abatement in housing (especially pre-1978 housing stock) to reduce a major complication pathway.
• Secondary prevention: Screening for iron deficiency in at-risk groups (pregnant women, children with developmental disabilities, CKD/dialysis patients) to catch and treat the reversible driver before pica-related complications occur.
• Behavioral/environmental interventions: Structured environmental modification and caregiver supervision in ASD/ID populations; parasite-prevention education (handwashing, safe water) in geophagia-endemic regions.
• Counseling: Genetic counseling relevant for syndromic causes (Smith-Magenis, Prader-Willi); antenatal counseling on pica risks (helminth exposure, heavy-metal contamination in some geophagic clays) is explicitly recommended by several African antenatal-care studies.
• Public health: Water/soil sanitation and deworming programs in geophagia-endemic regions; lead-abatement housing policy.

14. Other Species / Natural Disease

• Taxonomy: Reported informally in companion animals (dogs, cats — behavioral pica, e.g., ingestion of non-food objects, sometimes linked to nutritional deficiency or gastrointestinal disease) though this is a distinct veterinary literature not deeply cross-validated here; NCBITaxon:9615 (Canis lupus familiaris), NCBITaxon:9685 (Felis catus).
• Comparative biology / model relevance: The rodent "pica" model (below) is mechanistically analogous but serves a different biological function (emesis surrogate) than human pica, which is an important translational caveat — this is a candidate HUMAN_MODEL_MISMATCH note for curation, since rat kaolin-intake pica is a compensatory antiemetic behavior (a normal physiological substitute in a non-vomiting species) rather than a disease state, whereas human pica is itself the pathological entity.

15. Model Organisms

Rodent pica-as-emesis-proxy model (the dominant model-organism literature under the term "pica"): - Species: Rat (Rattus norvegicus), mouse (Mus musculus) — species that cannot vomit - Model type: Induced/pharmacological — kaolin (clay) consumption induced by emetogenic agents (cisplatin, copper sulfate, radiation, motion) serves as a quantifiable surrogate for emesis/nausea, not a direct model of human pica pathology: "Since rats lack a vomiting response... kaolin consumption (pica behavior) can indirectly reflect the degree of vomiting in rats" and "pica in rats is analogous to emesis... mediated by the same mechanisms as vomiting in humans." - Mechanism reproduced: Dose-dependent kaolin intake following cisplatin/copper sulfate, mediated via dopamine D2 receptors in the chemoreceptor trigger zone and 5-HT3 receptors on gastric vagal afferents; blocked by ondansetron and other clinical antiemetics (5-HT3/NK1 antagonists, corticosteroids) — validating the model's translational relevance to human chemotherapy-induced nausea/vomiting (CINV), not to human pica per se. - Adaptive-response framing: One line of research frames kaolin consumption as adaptive/protective — "kaolin consumption helps rats recover from chemotherapy-induced illness" — reinforcing that this rodent behavior, while phenotypically named "pica," is a physiologically distinct, arguably beneficial behavior rather than a disease model. - Limitations: This model does not recapitulate the core human disease features (chronic craving behavior, nutrient-deficiency linkage, ASD/ID-associated automatic reinforcement); it is best used for CINV/antiemetic pharmacology research, not for modeling human pica pathophysiology directly. No dedicated genetic mouse model (knockout/transgenic) of nutrient-deficiency-driven or ASD-associated pica behavior was identified in this search — a clear model-system gap. - Resources: No MGI/RGD-curated "pica" phenotype term beyond general behavioral/ingestive-behavior annotations was found in this pass; would require a dedicated MGI phenotype-ontology query to confirm.

Key Knowledge Gaps (for curation flagging)

1. No confirmed human neuroimaging (DAT-PET/SPECT) data directly testing the dopamine-deficiency hypothesis in pica patients — the mechanism is inferred from the iron-deficiency/dopamine literature generally, not measured directly in pica cohorts (candidate KNOWLEDGE_GAP).
2. The rodent kaolin/emesis pica model's translational relevance to human craving-driven pica is uncertain — candidate HUMAN_MODEL_MISMATCH (the rodent model captures an antiemetic behavior, not the human disease's core phenomenology).
3. No RCT-level pharmacotherapy evidence for pica itself (iron-repletion evidence is observational/case-series-based; NAC evidence is extrapolated from related BFRB conditions).
4. No dedicated GWAS, ClinVar, or OMIM entries for pica as an isolated trait.

Sources

• DSM-5-TR Update Supplement
• Pica - Merck Manual Professional Edition
• Pica: Prevalence and developmental comorbidity - Frontiers
• Pica - StatPearls
• Pica and iron-deficiency anaemia - PubMed (PMID:1914087)
• The Association Between Pica and Iron-Deficiency Anemia: A Scoping Review - PubMed (PMID:37220446)
• Pica as a manifestation of iron deficiency
• Covariates of Pica among Pregnant Women, Kawempe Hospital, Uganda - PubMed (PMID:34252052)
• Meta-analysis of worldwide prevalence of pica during pregnancy - ScienceDirect (PMID:26892693)
• Potential health risk assessment of toxic metals in clay pica, Ghana - PMC
• Pica, Autism, and Other Disabilities - Pediatrics (PMID:33408069)
• The Neurology and Psychopathology of Pica - PubMed (PMID:35674869)
• Zinc in the Monoaminergic Theory of Depression - PMC
• An Update on Pica: Prevalence, Contributing Causes, and Treatment - Psychiatric Times
• An Evaluation of Differential Reinforcement in the Treatment of Pica - PubMed
• Behavioral Interventions to Reduce the Pica of Persons with Developmental Disabilities - SAGE
• Pica in rats is analogous to emesis - PubMed (PMID:8415820)
• Pica--a model of nausea? Species differences in response to cisplatin - PubMed (PMID:15939445)
• Pica as an adaptive response: Kaolin consumption helps rats recover from chemotherapy-induced illness - ScienceDirect
• Cisplatin-Induced Anorexia and Pica Behavior in Rats - PMC
• Pica: Common but Commonly Missed - JABFM
• Rapunzel Syndrome Resulting in Multiple Sites of Simultaneous Intussusception - PMC
• Complications of Bezoar in Children - PMC
• Kleine-Levin syndrome in a boy with Prader-Willi syndrome - PubMed (PMID:8650457)
• Individuals with Smith-Magenis syndrome display... food-related behaviors equivalent to Prader-Willi syndrome - ResearchGate
• Pica in Pediatric Sickle Cell Disease - PubMed (PMID:31659594)
• Pica in end-stage chronic kidney disease: Literature review - PubMed (PMID:30360922)
• Pica, ARFID, Rumination Disorder Interview (PARDI) - AEDRTC Hub
• Ferritin: A Biomarker Requiring Caution in Clinical Decision - PMC
• The Potential of N-Acetylcysteine for Treatment of Trichotillomania, Excoriation Disorder, Onychophagia - PubMed (PMID:35681955)
• Mondo Disease Ontology
• Pica Disease - MalaCards

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on: 1. Key concepts and definitions with current understanding 2. Recent developments and latest research (prioritize 2023-2024 sources) 3. Current applications and real-world implementations 4. Expert opinions and analysis from authoritative sources 5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available. Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Disease Characteristics Research Template

Target Disease

• Disease Name: Pica
• MONDO ID: (if available)
• Category: Psychiatric

Research Objectives

Please provide a comprehensive research report on Pica covering all of the disease characteristics listed below. This report will be used to populate a disease knowledge base entry. Be thorough and cite primary literature (PMID preferred) for all claims.

For each section, suggested databases/resources are listed. These are the first places you should search for information on each topic.

1. Disease Information

Search first: OMIM, Orphanet, ICD-10/ICD-11, MeSH, PubMed

• What is the disease? Provide a concise overview.
• What are the key identifiers? (OMIM, Orphanet, ICD-10/ICD-11, MeSH, Mondo)
• What are the common synonyms and alternative names?
• Is the information derived from individual patients (e.g., EHR) or aggregated disease-level resources?

2. Etiology

• Disease Causal Factors: What are the primary causes? (genetic, environmental, infectious, mechanistic)
• Risk Factors:

  Search first: PubMed, Cochrane Library, UpToDate, clinical guidelines, ClinVar, ClinGen, GWAS Catalog, PheGenI, CTD, CDC, WHO, epidemiological databases

• Genetic risk factors (causal variants, susceptibility loci, modifier genes)
• Environmental risk factors (toxins, lifestyle, occupational exposures, age, sex, family history)
• Protective Factors:

  Search first: PubMed, Cochrane Library, clinical trial databases, GWAS Catalog, gnomAD, WHO, CDC, nutrition databases

• Genetic protective factors (protective variants, modifier alleles)
• Environmental protective factors (diet, lifestyle, exposures that reduce risk)
• Gene-Environment Interactions: How do genetic and environmental factors interact to influence disease?

  Search first: CTD, PubMed, PheGenI, GxE databases

3. Phenotypes

Search first: HPO (Human Phenotype Ontology), OMIM, Orphanet, PubMed, clinicaltrials.gov, MedDRA, SNOMED CT, DECIPHER, LOINC

For each phenotype, provide: - Phenotype type: symptoms, clinical signs, physical manifestations, behavioral changes, or laboratory abnormalities

For symptoms/signs: HPO, OMIM, Orphanet, PubMed For behavioral changes: HPO, DSM, RDoC (Research Domain Criteria), PubMed For laboratory abnormalities: LOINC, SNOMED CT, LabTests Online, PubMed - Phenotype characteristics: Search first: OMIM, Orphanet, HPO, PubMed - Age of symptom onset (neonatal, childhood, adult-onset, late-onset) - Symptom severity (mild, moderate, severe, variable) - Symptom progression (stable, progressive, episodic, fluctuating) - Frequency among affected individuals (percentage or qualitative) - Quality of life impact: Effects on daily functioning and well-being (per-phenotype when possible) Search first: EQ-5D database, SF-36, WHO QOL databases, PubMed - Suggest HPO (Human Phenotype Ontology) terms for each phenotype

4. Genetic/Molecular Information

• Causal Genes: Gene mutations or chromosomal abnormalities responsible for disease (gene symbols, OMIM IDs)

  Search first: OMIM, ClinVar, HGMD, Ensembl, NCBI Gene

• Pathogenic Variants:
• Affected genes (gene symbols, HGNC IDs) > Search first: OMIM, NCBI Gene, Ensembl, HGNC, UniProt, GeneCards
• Variant classification (pathogenic, likely pathogenic, VUS per ACMG/AMP guidelines) > Search first: ClinVar, ClinGen, ACMG/AMP guidelines, VarSome
• Variant type/class (missense, frameshift, nonsense, splice-site, structural)
• Allele frequency in population databases > Search first: gnomAD, 1000 Genomes, ExAC, TOPMed, dbSNP
• Somatic vs germline origin > Search first: COSMIC (somatic), ClinVar, ICGC, TCGA
• Functional consequences (loss of function, gain of function, dominant negative)
• Modifier Genes: Genes that modify disease severity or expression
• Epigenetic Information: DNA methylation, histone modifications, chromatin changes affecting disease

  Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth

• Chromosomal Abnormalities: Large-scale genetic changes (aneuploidy, translocations, inversions)

  Search first: DECIPHER, ClinVar, ECARUCA, UCSC Genome Browser

5. Environmental Information

• Environmental Factors: Non-genetic contributing factors (toxins, radiation, pollution, occupational exposure)

  Search first: CTD (Comparative Toxicogenomics Database), TOXNET, PubMed, EPA databases

• Lifestyle Factors: Behavioral factors (smoking, diet, exercise, alcohol consumption)

  Search first: CDC databases, WHO, PubMed, NHANES

• Infectious Agents: If applicable, pathogens causing or triggering disease (bacteria, viruses, fungi, parasites)

  Search first: NCBI Taxonomy, ViPR, BV-BRC, MicrobeDB, GIDEON

6. Mechanism / Pathophysiology

• Molecular Pathways: Specific signaling cascades or biochemical pathways involved (Wnt, MAPK, mTOR, PI3K-AKT, etc.)

  Search first: KEGG, Reactome, WikiPathways, PathBank, BioCyc

• Cellular Processes: Cell-level mechanisms (apoptosis, autophagy, cell cycle dysregulation, inflammation, etc.)

  Search first: Gene Ontology (GO), Reactome, KEGG, PubMed

• Protein Dysfunction: How protein structure or function is altered (misfolding, aggregation, loss of function, gain of function)

  Search first: UniProt, PDB (Protein Data Bank), InterPro, Pfam, AlphaFold

• Metabolic Changes: Alterations in metabolic processes (energy metabolism, lipid metabolism, amino acid metabolism)

  Search first: KEGG, BioCyc, HMDB (Human Metabolome Database), BRENDA

• Immune System Involvement: Role of immune response (autoimmunity, immunodeficiency, chronic inflammation)

  Search first: ImmPort, Immunome Database, IEDB, Gene Ontology

• Tissue Damage Mechanisms: How tissues/ are injured (oxidative stress, ischemia, fibrosis, necrosis)

  Search first: PubMed, Gene Ontology, Reactome

• Biochemical Abnormalities: Specific molecular defects (enzyme deficiencies, receptor dysfunction, ion channel defects)

  Search first: BRENDA, UniProt, KEGG, OMIM, PubMed

• Epigenetic Changes: DNA methylation, histone modifications affecting gene expression in disease

  Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth

• Molecular Profiling (if available):
• Transcriptomics/gene expression changes > Search first: GEO (Gene Expression Omnibus), ArrayExpress, GTEx, Human Cell Atlas, SRA
• Proteomics findings > Search first: PRIDE, ProteomeXchange, Human Protein Atlas, STRING, BioGRID
• Metabolomics signatures > Search first: MetaboLights, Metabolomics Workbench, HMDB, METLIN
• Lipidomics alterations > Search first: LIPID MAPS, SwissLipids, LipidHome, Metabolomics Workbench
• Genomic structural features > Search first: UCSC Genome Browser, Ensembl, NCBI, dbVar, DGV
• Advanced Technologies (if applicable):
• Single-cell analysis findings (cell-type specific mechanisms, cellular heterogeneity) > Search first: Human Cell Atlas, Single Cell Portal, GEO, CELLxGENE
• Spatial transcriptomics findings > Search first: GEO, Spatial Research, Vizgen, 10x Genomics data
• Multi-omics integration results > Search first: TCGA, ICGC, cBioPortal, LinkedOmics, PubMed
• Functional genomics screens (CRISPR, RNAi) > Search first: DepMap, GenomeRNAi, PubMed, BioGRID ORCS

For each mechanism, describe: - The causal chain from initial trigger to clinical manifestation - Which mechanisms are upstream vs downstream - What cell types and biological processes are involved - Suggest GO terms for biological processes and CL terms for cell types

7. Anatomical Structures Affected

• Organ Level:
• Primary organs directly affected
• Secondary organ involvement (complications, secondary effects)
• Body systems involved (cardiovascular, nervous, digestive, respiratory, endocrine, etc.)

  Search first: Uberon, FMA (Foundational Model of Anatomy), OMIM, HPO, ICD-11, MeSH, SNOMED CT

• Tissue and Cell Level:
• Specific tissue types affected (epithelial, connective, muscle, nervous)
• Specific cell populations targeted (with Cell Ontology terms)

  Search first: Uberon, Human Protein Atlas, Cell Ontology, Human Cell Atlas, CellMarker, PanglaoDB

• Subcellular Level:
• Cellular compartments involved (mitochondria, nucleus, ER, lysosomes) (with GO Cellular Component terms)

  Search first: Gene Ontology (Cellular Component), UniProt, Human Protein Atlas

• Localization:
• Specific anatomical sites (with UBERON terms) > Search first: FMA, Uberon, NeuroNames (for brain), SNOMED CT
• Lateralization (unilateral, bilateral, asymmetric) > Search first: HPO, clinical literature, imaging databases

8. Temporal Development

• Onset:
• Typical age of onset (congenital, pediatric, adult, geriatric)
• Onset pattern (acute, subacute, chronic, insidious)

  Search first: OMIM, Orphanet, HPO, PubMed

• Progression:
• Disease stages (early, intermediate, advanced, end-stage) > Search first: Cancer Staging Manual (AJCC), WHO classifications, PubMed
• Progression rate (rapid, slow, variable)
• Disease course pattern (episodic, relapsing-remitting, progressive, stable)
• Disease duration (self-limited, chronic lifelong)

  Search first: Disease registries, longitudinal cohort databases, natural history studies, PubMed, Orphanet, OMIM

• Patterns:
• Remission patterns (spontaneous, treatment-induced) > Search first: Clinical trial databases, disease registries, PubMed
• Critical periods (time windows of vulnerability or opportunity for intervention) > Search first: PubMed, developmental biology databases, clinical guidelines

9. Inheritance and Population

• Epidemiology:
• Prevalence (cases per 100,000 at given time)
• Incidence (new cases per 100,000 per year)

  Search first: Orphanet, CDC, WHO, GBD (Global Burden of Disease), national registries, SEER, disease registries

• For Genetic Etiology:
• Inheritance pattern (AD, AR, X-linked, mitochondrial, multifactorial, polygenic) > Search first: OMIM, Orphanet, ClinVar, GTR (Genetic Testing Registry)
• Penetrance (complete, incomplete, age-dependent) > Search first: ClinVar, OMIM, PubMed, ClinGen
• Expressivity (variable, consistent) > Search first: OMIM, ClinVar, PubMed
• Genetic anticipation (increasing severity in successive generations) > Search first: OMIM, PubMed (especially for repeat expansion disorders)
• Germline mosaicism > Search first: ClinVar, OMIM, genetic counseling literature, PubMed
• Founder effects (population-specific mutations) > Search first: gnomAD, population genetics databases, PubMed
• Consanguinity role > Search first: OMIM, population studies, genetic counseling resources
• Carrier frequency > Search first: gnomAD, carrier screening databases, GeneReviews, GTR
• Population Demographics:
• Affected populations (ethnic or demographic groups with higher prevalence) > Search first: gnomAD, 1000 Genomes, PAGE Study, PubMed, population registries
• Geographic distribution (endemic areas, regional variation) > Search first: WHO, CDC, GBD, Orphanet, geographic epidemiology databases
• Geographic distribution of specific variants
• Sex ratio (male:female) > Search first: Disease registries, OMIM, PubMed, epidemiological databases
• Age distribution of affected individuals > Search first: CDC, disease registries, SEER, Orphanet

10. Diagnostics

• Clinical Tests:
• Laboratory tests (blood, urine, tissue chemistry, specific enzyme assays) > Search first: LOINC, LabTests Online, PubMed
• Biomarkers (proteins, metabolites, genetic markers, circulating biomarkers) > Search first: FDA Biomarker List, BEST (Biomarkers, EndpointS, and other Tools), PubMed
• Imaging studies (X-ray, CT, MRI, PET, ultrasound) > Search first: RadLex, DICOM, Radiopaedia, imaging databases
• Functional tests (pulmonary function, cardiac stress tests) > Search first: LOINC, clinical guidelines, PubMed
• Electrophysiology (EEG, EMG, ECG, nerve conduction studies) > Search first: LOINC, clinical neurophysiology databases, PubMed
• Biopsy findings (histopathology, immunohistochemistry) > Search first: SNOMED CT, College of American Pathologists resources, PubMed
• Pathology findings (microscopic examination) > Search first: SNOMED CT, Digital Pathology databases, PubMed
• Genetic Testing:

  Search first: GTR (Genetic Testing Registry), GeneReviews, ClinGen

• Overview of recommended genetic testing approach
• Whole genome sequencing (WGS) utility > Search first: GTR, ClinVar, GEL (Genomics England), gnomAD
• Whole exome sequencing (WES) utility > Search first: GTR, ClinVar, OMIM, GeneMatcher
• Gene panels (which panels, which genes) > Search first: GTR, ClinVar, laboratory-specific databases
• Single gene testing > Search first: GTR, ClinVar, OMIM, GeneReviews
• Chromosomal microarray (CMA) > Search first: DECIPHER, ClinVar, dbVar, ECARUCA
• Karyotyping > Search first: Chromosome Abnormality Database, ClinVar, cytogenetics resources
• FISH > Search first: ClinVar, cytogenetics databases, PubMed
• Mitochondrial DNA testing > Search first: MITOMAP, MSeqDR, ClinVar, GTR
• Repeat expansion testing > Search first: GTR, ClinVar, repeat expansion databases, PubMed
• Omics-Based Diagnostics (if applicable):
• RNA sequencing / transcriptomics > Search first: GEO, ArrayExpress, GTEx, RNA-seq databases
• Proteomics > Search first: PRIDE, ProteomeXchange, FDA Biomarker database
• Metabolomics > Search first: MetaboLights, Metabolomics Workbench, HMDB
• Epigenomics > Search first: GEO, ENCODE, Roadmap Epigenomics, MethBase
• Liquid biopsy > Search first: COSMIC, ClinVar, liquid biopsy databases, PubMed
• Clinical Criteria:
• Standardized diagnostic criteria (DSM, ICD, society guidelines) > Search first: DSM-5, ICD-11, clinical society guidelines, UpToDate
• Differential diagnosis (other conditions to rule out, with distinguishing features) > Search first: DynaMed, UpToDate, clinical decision support systems
• Screening:
• Screening methods for asymptomatic individuals (newborn screening, carrier screening, cascade screening) > Search first: ACMG recommendations, CDC newborn screening, GTR

11. Outcome/Prognosis

• Survival and Mortality:
• Survival rate (5-year, 10-year, overall) > Search first: SEER, cancer registries, disease-specific registries, PubMed
• Life expectancy (with and without treatment if applicable) > Search first: Orphanet, disease registries, actuarial databases, PubMed
• Mortality rate > Search first: CDC, WHO, GBD, national mortality databases
• Disease-specific mortality (deaths directly attributable to disease) > Search first: Disease registries, CDC Wonder, GBD, PubMed
• Morbidity and Function:
• Morbidity (disease-related disability and health impacts) > Search first: GBD, WHO, disability databases, PubMed
• Disability outcomes (long-term functional impairments) > Search first: ICF (International Classification of Functioning), disability registries
• Quality of life measures (EQ-5D, SF-36, PROMIS, disease-specific tools) > Search first: EQ-5D database, SF-36, PROMIS, PubMed
• Disease Course:
• Complications (secondary problems: infections, organ failure, etc.) > Search first: ICD codes, disease registries, clinical databases, PubMed
• Recovery potential (likelihood and extent of recovery, with vs without treatment) > Search first: Natural history studies, rehabilitation databases, PubMed
• Prediction:
• Prognostic factors (age, disease severity, biomarkers, treatment response) > Search first: Prognostic models databases, clinical calculators, PubMed
• Prognostic biomarkers (molecular markers predicting disease course) > Search first: FDA Biomarker database, PubMed, cancer prognostic databases

12. Treatment

• Pharmacotherapy:
• Pharmacological treatments (drug names, drug classes, mechanisms of action) > Search first: DrugBank, RxNorm, ATC classification, DailyMed, FDA databases
• Pharmacogenomics (how genetic variants affect drug metabolism, efficacy, toxicity) > Search first: PharmGKB, CPIC (Clinical Pharmacogenetics), FDA Table of PGx Biomarkers
• Advanced Therapeutics:
• Gene therapy (viral vectors, CRISPR, gene replacement, gene editing) > Search first: ClinicalTrials.gov, FDA gene therapy database, ASGCT resources
• Cell therapy (stem cell transplant, CAR-T, cellular therapeutics) > Search first: ClinicalTrials.gov, FDA cell therapy database, FACT standards
• RNA-based therapies (ASOs, siRNA, mRNA therapies) > Search first: ClinicalTrials.gov, FDA approvals, PubMed
• Targeted therapies (treatments directed at specific molecular targets) > Search first: My Cancer Genome, OncoKB, ClinicalTrials.gov, FDA approvals
• Immunotherapies (checkpoint inhibitors, monoclonal antibodies) > Search first: Cancer Immunotherapy Database, FDA approvals, ClinicalTrials.gov
• Surgical and Interventional:
• Surgical interventions (types of surgery, timing, outcomes) > Search first: CPT codes, surgical registries, clinical guidelines, PubMed
• Supportive and Rehabilitative:
• Supportive care (symptom management, pain control, nutrition) > Search first: Clinical guidelines, Cochrane Library, PubMed
• Rehabilitation (physical therapy, occupational therapy, speech therapy) > Search first: Rehabilitation medicine databases, clinical guidelines, PubMed
• Experimental:
• Experimental treatments in clinical trials (with NCT identifiers if available) > Search first: ClinicalTrials.gov, EU Clinical Trials Register, WHO ICTRP
• Treatment Outcomes:
• Treatment response rates > Search first: Clinical trial databases, FDA reviews, systematic reviews, PubMed
• Side effects and adverse events > Search first: FDA Adverse Event Reporting System (FAERS), MedWatch, PubMed
• Treatment Strategy:
• Treatment algorithms (clinical pathways, decision trees) > Search first: Clinical practice guidelines, NCCN Guidelines, UpToDate
• Combination therapies > Search first: ClinicalTrials.gov, treatment guidelines, PubMed
• Personalized medicine approaches (genotype-guided treatment) > Search first: My Cancer Genome, CIViC, PharmGKB, precision medicine databases

For each treatment, suggest MAXO (Medical Action Ontology) terms where applicable.

13. Prevention

• Prevention Levels:
• Primary prevention (preventing disease occurrence: vaccination, risk factor modification) > Search first: CDC, WHO, USPSTF recommendations, Cochrane Library
• Secondary prevention (early detection and treatment: screening programs, early intervention) > Search first: USPSTF, CDC screening guidelines, WHO
• Tertiary prevention (preventing complications in those with disease) > Search first: Clinical guidelines, disease management protocols, PubMed
• Immunization: Vaccine strategies (if applicable)

  Search first: CDC vaccine schedules, WHO immunization, FDA vaccine database

• Screening and Early Detection:
• Screening programs (population-based: newborn screening, cancer screening) > Search first: CDC screening programs, USPSTF, cancer screening databases
• Genetic screening (carrier screening, preimplantation genetic diagnosis, prenatal testing) > Search first: ACMG recommendations, ACOG guidelines, GTR
• Risk stratification (identifying high-risk individuals for targeted prevention) > Search first: Risk prediction models, clinical calculators, PubMed
• Behavioral Interventions: Lifestyle modifications to reduce risk

  Search first: CDC, WHO, behavioral intervention databases, Cochrane Library

• Counseling: Genetic counseling (risk assessment, family planning guidance)

  Search first: NSGC resources, ACMG guidelines, GeneReviews

• Public Health:
• Public health interventions (sanitation, vector control, health education) > Search first: CDC, WHO, public health databases, PubMed
• Environmental interventions (reducing environmental risk factors) > Search first: EPA databases, WHO environmental health, PubMed
• Prophylaxis: Preventive medications or procedures

  Search first: Clinical guidelines, FDA approvals, PubMed

14. Other Species / Natural Disease

• Taxonomy: Species affected (with NCBI Taxon identifiers)

  Search first: NCBI Taxonomy

• Breed: Specific breeds affected (with VBO identifiers if applicable)

  Search first: VBO (Vertebrate Breed Ontology)

• Gene: Orthologous genes in other species (with NCBI Gene IDs)

  Search first: NCBI Gene

• Natural Disease:
• Naturally occurring disease in other species (companion animals, wildlife) > Search first: OMIA (Online Mendelian Inheritance in Animals), VetCompass, PubMed
• Veterinary relevance and importance in animal health > Search first: OMIA, veterinary databases, PubMed
• Comparative Biology:
• Comparative pathology (similarities and differences across species) > Search first: OMIA, comparative pathology databases, PubMed
• Evolutionary conservation of disease mechanisms > Search first: HomoloGene, OrthoMCL, Alliance of Genome Resources
• Transmission (if applicable):
• Zoonotic potential > Search first: CDC zoonotic diseases, WHO zoonoses, GIDEON
• Cross-species susceptibility > Search first: NCBI Taxonomy, veterinary databases, PubMed

15. Model Organisms

• Model Types:
• Model organism type (mammalian, invertebrate, cellular, in vitro) > Search first: Alliance of Genome Resources, model organism databases
• Specific model systems (mouse, rat, zebrafish, Drosophila, C. elegans, yeast, cell lines, organoids, iPSCs) > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, SGD, ATCC, Cellosaurus
• Induced models (drug treatment, surgical intervention, environmental manipulation) > Search first: MGI, model organism databases, PubMed
• Genetic Models:
• Types available (knockout, knock-in, transgenic, conditional, humanized) > Search first: MGI, IMPC, KOMP, EuMMCR, IMSR
• Model Characteristics:
• Phenotype recapitulation (how well model reproduces human disease features) > Search first: Model organism databases, comparative studies, PubMed
• Model limitations (aspects of human disease not captured) > Search first: Model organism databases, PubMed, review articles
• Applications:
• Research applications (what aspects of disease can be studied) > Search first: Model organism databases, PubMed
• Resources:
• Model databases > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, IMSR, EMMA, MMRRC

Citation Requirements

• Cite primary literature (PMID preferred) for all mechanistic and clinical claims
• Prioritize recent reviews and landmark papers
• Include direct quotes from abstracts where possible to support key statements
• Distinguish evidence source types: human clinical, model organism, in vitro, computational

Output Format

Structure your response as a comprehensive narrative organized by the sections above. For each section, provide: - Factual content with specific details (numbers, percentages, gene names, variant nomenclature) - Ontology term suggestions (HPO, GO, CL, UBERON, CHEBI, MAXO, MONDO) where applicable - Evidence citations with PMIDs - Direct quotes from abstracts to support key claims - Clear indication when information is not available or not applicable for this disease

This report will be used to populate a disease knowledge base entry with: - Pathophysiology descriptions with causal chains - Gene/protein annotations (HGNC, GO terms) - Phenotype associations (HP terms) with frequencies - Cell type involvement (CL terms) - Anatomical locations (UBERON terms) - Chemical entities (CHEBI terms) - Treatment annotations (MAXO terms) - Evidence items with PMIDs and exact abstract quotes - Epidemiology, prognosis, diagnostic, and prevention information - Animal model descriptions with phenotype recapitulation details

Pica: comprehensive disease-characteristics report

Executive summary

Pica is a feeding and eating disorder defined by persistent ingestion of non-nutritive, non-food substances for at least 1 month when the behavior is developmentally inappropriate and not part of a culturally or socially normative practice. Common forms include geophagia (earth/clay), pagophagia (ice), amylophagia (raw starch), trichophagia (hair), and ingestion of paper, paint, plaster, fabric, metal, or feces. It is a behaviorally defined, heterogeneous syndrome, not a single-gene metabolic disease. Its most reproducible associations are early childhood, pregnancy, autism spectrum disorder (ASD), intellectual/developmental disability (ID/DD), iron deficiency/anemia, sensory-seeking behavior, psychosocial adversity, and access to ingestible hazardous materials. Association does not establish direction of causation, particularly for iron deficiency.

The strongest recent longitudinal evidence is Papini et al. (online 2023; journal issue 2024), which found caregiver-reported pica behavior in 312/10,109 children (3.08%); prevalence was highest at 36 months (2.29%) and declined to 0.33% at 115 months. Of children ever reported to have pica, 19.55% had reports at two or more waves. The investigators explicitly cautioned that their measure did not establish all DSM criteria, including 1-month duration and cultural/developmental exclusions (https://doi.org/10.1002/eat.24111; published in International Journal of Eating Disorders, 2024) (papini2024prevalenceandrecurrence pages 1-3, papini2024prevalenceandrecurrence pages 11-13, papini2023prevalenceandrecurrence pages 7-11).

Table: This table condenses the most useful ontology-ready evidence for pica across diagnosis, epidemiology, complications, treatment, and evidence gaps. It is designed to support knowledge-base curation while clearly separating strong findings from limitations in the available literature.

1. Disease information

Definition and category

Pica is classified as a feeding/eating disorder. The core phenotype is repeated consumption of substances that have no conventional nutritional role. Normal infant mouthing, culturally sanctioned geophagia, and accidental foreign-body ingestion are not sufficient for the diagnosis. If pica occurs with another mental or medical disorder—including ASD, ID, schizophrenia, pregnancy, or iron deficiency—it should be diagnosed separately when sufficiently severe to warrant clinical attention (leung2019picaacommon pages 1-2, leung2019picaacommon pages 3-4).

Common names and phenotype labels: pica disorder, allotriophagy, non-food ingestion, dirt eating; geophagia/geophagy, pagophagia, amylophagia, trichophagia, lithophagia, and coprophagia describe substance-specific presentations rather than universally distinct diseases.

Identifiers

The evidence summarized here is primarily aggregated disease-level literature—birth cohorts, case-control studies, reviews, and case reports—not individual EHR-derived patient data. SEED used standardized assessments/questionnaires; ALSPAC used repeated caregiver reports (fields2021picaautismand pages 3-4, fields2021picaautismand pages 4-6).

2. Etiology, risk, and protective factors

Pica is best modeled as multifactorial.

• Neurodevelopmental factors: ASD, ID, and ASD-like characteristics are major risk markers. In SEED, pica prevalence was 23.2% in ASD, 8.4% in other DD, and 3.5% in population controls. Rates were 28.1% in ASD with ID, 14.0% in ASD without ID, and 26.3% in DD with both ID and ASD characteristics. Adjusted prevalence ratios for ASD-related groups were approximately 4.4–8.0 (Fields et al., Pediatrics, February 2021; https://doi.org/10.1542/peds.2020-0462) (fields2021picaautismand pages 4-6, fields2021picaautismand pages 1-3).
• Micronutrient/hematologic factors: Iron deficiency and anemia are consistently associated with pica, especially pagophagia and geophagia. A review citing a meta-analysis of 6,407 pica cases reported 2.35-fold higher odds of anemia. Zinc deficiency has also been reported, but evidence is less consistent. Reverse causality is plausible: deficiency may trigger craving, while clay/soil can bind iron or replace nutritious food and worsen deficiency (Leung & Hon, December 2019; https://doi.org/10.2174/1573396315666190313163530) (leung2019picaacommon pages 2-3, leung2019picaacommon pages 3-4).
• Sensory and reinforcement factors: Taste, texture, smell, oral stimulation, automatic reinforcement, inability to discriminate edible from inedible objects, and socially mediated reinforcement may maintain behavior. Sensory-processing difficulties in ASD provide a plausible pathway but are not a universal mechanism (papini2024prevalenceandrecurrence pages 3-4, fields2021picaautismand pages 6-8).
• Psychosocial/environmental factors: Lower socioeconomic status, neglect, emotional deprivation, family stress, maternal separation, migration/refugee status, and ready access to soil, peeling paint, or other hazardous material are reported risk correlates (leung2019picaacommon pages 2-3, leung2019picaacommon pages 1-2).
• Physiologic states and comorbidity: Pregnancy is a recognized context, as are sickle-cell disease, schizophrenia, obsessive-compulsive symptoms, depression, and other eating disturbances. These associations are heterogeneous and do not imply that each condition causes pica (leung2019picaacommon pages 2-3, leung2019picaacommon pages 1-2).

Protective factors: No validated genetic protective variant is known. Plausible environmental protection includes adequate iron and dietary nutrition, early developmental/behavioral screening, caregiver supervision, restricted access to hazardous items, lead-safe housing, and treatment of psychosocial stress. These are prevention/management principles rather than quantified causal protective effects (fields2021picaautismand pages 6-8).

Gene–environment interaction: No pica-specific G×E locus has been established. A reasonable but unproven model is that genetically influenced neurodevelopmental traits alter sensory processing, discrimination, or behavioral flexibility, while nutritional deficiency, stress, and environmental availability determine whether ingestion emerges and what is consumed.

3. Phenotypes

Pica can begin after infancy, in childhood, during pregnancy, or in adulthood. In ALSPAC, it peaked at 36 months and generally declined; nine children showed fluctuating persistence from 36 to 115 months. ASD-associated rates remained approximately 10–14% across sampled ages, whereas population rates fell markedly. These findings indicate predominantly transient childhood behavior with a clinically important persistent subgroup (papini2023prevalenceandrecurrence pages 7-11).

Quality-of-life evidence is sparse and no validated pica-specific PROM is established. Reported impacts include constant supervision, restricted social participation, caregiver distress, disrupted family relationships, dental/medical burden, hospitalization, and surgery. The 2024 cohort paper cites weaker family relationships and reduced social contact, but quantitative EQ-5D/SF-36 estimates are unavailable (papini2024prevalenceandrecurrence pages 1-3).

4. Genetic and molecular information

No pica-specific causal gene, HGNC locus, pathogenic germline or somatic variant, chromosomal abnormality, modifier gene, Mendelian inheritance pattern, penetrance estimate, carrier frequency, founder variant, or validated pharmacogenomic marker is established in the retrieved disease-focused evidence. Therefore, assigning variants associated with ASD, ID, schizophrenia, or iron disorders directly to pica would be inappropriate.

Likewise, there is no validated pica-specific DNA-methylation signature, histone/chromatin alteration, transcriptomic profile, proteomic signature, metabolomic/lipidomic classifier, single-cell atlas, spatial-transcriptomic result, multi-omics model, or CRISPR/RNAi screen. WES, WGS, gene panels, CMA, karyotyping, FISH, mtDNA analysis, and repeat-expansion testing are not diagnostic tests for isolated pica. Genetic testing is appropriate only when developmental delay, dysmorphism, neurologic findings, congenital anomalies, or family history independently indicate an underlying genetic syndrome.

5. Environmental information

The clinically important environmental exposures are determined by the ingested substance:

• old paint, household dust, contaminated soil, imported remedies, pottery glaze, or occupational take-home dust → lead or other heavy metals;
• soil/feces → Toxocara, Ascaris, Toxoplasma, and other geographically specific pathogens;
• hair/fibers/plastic/metal → bezoar, obstruction, perforation, or toxicity;
• clay/starch → displacement of nutritious food, constipation, and impaired micronutrient absorption.

Dietary iron insufficiency and food insecurity may contribute. Smoking, alcohol, and exercise are not established primary pica determinants. Pica itself is not infectious or transmissible; infectious agents are complications of exposure, not causes of the psychiatric syndrome (leung2019picaacommon pages 2-3, leung2019picaacommon pages 3-4, fields2021picaautismand pages 1-3).

6. Mechanism and pathophysiology

There is no single established molecular pathway. Current evidence supports several partially overlapping causal chains:

1. Micronutrient pathway: inadequate intake/blood loss/increased requirement → iron depletion and anemia → altered appetite or sensory reward → craving/ingestion. Alternatively, soil/clay ingestion → iron binding, reduced absorption, or dietary displacement → worsening deficiency. Directionality remains unresolved (leung2019picaacommon pages 2-3).
2. Neurodevelopmental-sensory pathway: ASD/ID-associated sensory processing or poor edible–inedible discrimination → oral sensory seeking/non-food ingestion → reinforcement by texture/taste or stimulation → persistence (fields2021picaautismand pages 6-8).
3. Behavioral pathway: stress, low stimulation, attention contingencies, or automatic oral reinforcement → repeated ingestion → learned maintenance. Functional analysis is used because the maintaining consequence differs by patient (fields2021picaautismand pages 6-8).
4. Downstream injury: repeated exposure → toxicant absorption, infection, tooth damage, nutrient displacement, choking, or foreign-body accumulation → anemia, neurologic toxicity, bezoar, obstruction, ischemia, perforation, sepsis, or surgery (leung2019picaacommon pages 3-4, fields2021picaautismand pages 1-3).

Candidate GO mappings should be treated as broad process annotations, not demonstrated pica pathways: sensory perception, feeding behavior, learning or memory, response to iron ion, intestinal absorption, and response to toxic substance. Candidate cell types include CNS neurons involved in reward/feeding and intestinal epithelial cells, but no pica-specific affected cell population has been demonstrated. Protein dysfunction, immune dysregulation, apoptosis, autophagy, or canonical Wnt/MAPK/mTOR/PI3K-AKT abnormalities are not established mechanisms.

7. Anatomical structures affected

Pica has no fixed primary lesion. The defining behavior is generated within nervous-system/behavioral circuitry, but anatomy depends on exposure:

• Digestive system: oral cavity/teeth, esophagus, stomach, small and large intestine; UBERON candidates include mouth, tooth enamel, stomach, small intestine, colon.
• Hematologic system: blood and bone marrow consequences of iron deficiency or blood loss.
• Nervous system: secondary injury from lead or other neurotoxins; CNS involvement may also reflect a comorbid neurodevelopmental disorder.
• Liver/kidney: possible secondary toxicant injury.
• Respiratory tract: choking or aspiration.

No laterality is expected. No disease-specific subcellular compartment or GO Cellular Component term is justified.

8. Temporal development

Onset is usually insidious/repetitive rather than acute, although complications may present acutely. Developmentally normal mouthing must be distinguished from pica. In ALSPAC, prevalence fell from 2.29% at 36 months to 0.33% at 115 months; 61/312 affected children (19.55%) had pica at ≥2 waves. Autism and DD were associated with pica at every assessed wave from 36 to 115 months (papini2024prevalenceandrecurrence pages 1-3, papini2023prevalenceandrecurrence pages 7-11).

The course may be self-limited after correction of deficiency or pregnancy, or chronic/relapsing in ASD/ID and severe psychiatric illness. There is no formal staging system. Critical intervention windows are early childhood, pregnancy, emergence of anemia, and any onset of abdominal pain, vomiting, choking, neurologic symptoms, or suspected toxic exposure.

9. Inheritance and population epidemiology

No reliable global incidence per 100,000 person-years is available, partly because studies use different definitions and often measure behavior rather than DSM diagnosis. Contemporary estimates include:

• ALSPAC: 3.08% ever reported across five childhood waves; 2.29% at 36 months and 0.33% at 115 months (papini2024prevalenceandrecurrence pages 1-3, papini2023prevalenceandrecurrence pages 7-11).
• SEED preschool sample: 3.5% in population controls, 23.2% in ASD, and 8.4% in DD (fields2021picaautismand pages 4-6).
• Earlier studies summarized in the 2019 review varied enormously by population and ascertainment, including 27.8% in a 70-study pregnancy meta-analysis. Such estimates should not be pooled with confirmed diagnostic prevalence (leung2019picaacommon pages 2-3).

In ALSPAC, boys had higher reported prevalence than girls at age 9 (0.49% versus 0.16%), but pica does not have a universally established sex ratio. Geographic and ethnic variation is strongly confounded by cultural definitions, pregnancy, poverty, food insecurity, soil/paint exposure, and measurement. There is no established AD, AR, X-linked, mitochondrial, or polygenic inheritance model; anticipation, mosaicism, consanguinity, and carrier frequency are not applicable to isolated pica.

10. Diagnostics

Clinical criteria

Diagnosis requires a careful interview establishing: (1) substances consumed; (2) frequency and ≥1-month duration; (3) developmental inappropriateness; (4) lack of cultural sanction; (5) access and context; and (6) clinical significance when another disorder or pregnancy is present. Caregiver observation is often necessary. A single questionnaire item identifies risk but does not establish diagnosis; ALSPAC could not assess all DSM requirements (papini2024prevalenceandrecurrence pages 11-13, fields2021picaautismand pages 3-4).

Exposure-directed workup

• CBC, ferritin, serum iron, transferrin saturation/TIBC; consider reticulocytes and inflammatory markers when interpreting ferritin.
• Blood lead concentration when paint, dust, soil, pottery, imported products, or unexplained developmental/abdominal findings are relevant; test other metals according to exposure.
• Zinc and broader nutritional assessment when diet is restricted or malnutrition is suspected.
• Stool or pathogen-directed testing when contaminated soil/feces was ingested and epidemiology or symptoms support infection.
• Abdominal radiography for radiopaque material, obstruction, or constipation; ultrasound/CT/endoscopy as clinically indicated for bezoar, perforation, or unexplained pain/vomiting.
• Dental examination and developmental/psychiatric assessment, including ASD/ID, OCD-spectrum symptoms, psychosis, mood disorder, trauma, and functional behavioral assessment.

Reviews specifically recommend testing for anemia, lead poisoning, parasites, and imaging for gastrointestinal complications (leung2019picaacommon pages 2-3, leung2019picaacommon pages 3-4).

Differential diagnosis

Exclude normal developmental mouthing, culturally sanctioned ingestion, accidental foreign-body ingestion, food insecurity without persistent non-food preference, ARFID, anorexia nervosa, rumination disorder, obsessive-compulsive behavior, psychosis/delusional ingestion, nonsuicidal self-injury, intentional poisoning, factitious disorder, dementia, Prader–Willi syndrome, and substance-specific behaviors such as trichotillomania with trichophagia. The distinction depends on motivation, duration, development, culture, and associated psychopathology.

No molecular biomarker, biopsy, EEG, PET/MRI signature, newborn screen, carrier screen, or population genetic screen exists for pica. The Pica, ARFID, and Rumination Disorder Interview (PARDI) can support structured assessment in children aged ≥2 years, but no available questionnaire captures every DSM criterion (papini2024prevalenceandrecurrence pages 10-11, papini2024prevalenceandrecurrence pages 11-13).

11. Outcome and prognosis

There are no meaningful pica-specific 5- or 10-year survival estimates. Mortality is uncommon but can occur through choking, poisoning, obstruction, perforation, sepsis, or severe toxic exposure. Morbidity ranges from minimal transient behavior to anemia, developmental neurotoxicity, parasitosis, dental injury, repeated hospitalization, and emergency surgery (leung2019picaacommon pages 3-4, fields2021picaautismand pages 1-3).

Prognosis is generally favorable for developmentally typical children when hazards are removed, deficiencies corrected, and discrimination/supervision established. Persistence is more likely where behavior is strongly automatically reinforced or accompanied by ASD/ID, severe psychiatric illness, continued stress, or continued access. Substance type, frequency, toxic burden, GI symptoms, iron status, developmental capacity, caregiver resources, and response to behavioral intervention are practical prognostic indicators. No validated molecular prognostic biomarker exists.

12. Treatment

No medication is approved specifically for pica, and no relevant pica-specific interventional trial was identified in the ClinicalTrials.gov search. Evidence is dominated by observational studies, single-case experimental designs, and specialist behavioral series rather than large randomized trials.

Recommended stepped strategy

1. Immediate safety/environmental control: remove or lock away preferred hazardous items; repair peeling paint; increase supervision; alert school/daycare and all caregivers; provide safe competing activities/items. Candidate MAXO: environmental modification, caregiver education, safety monitoring (fields2021picaautismand pages 6-8).
2. Medical correction: treat iron deficiency with iron replacement and address bleeding/dietary causes; correct other demonstrated deficiencies rather than prescribing empirically. Treat lead toxicity, parasites, constipation, dental injury, or poisoning according to standard protocols. Candidate MAXO: laboratory monitoring, iron supplementation, toxicant removal/chelation where indicated, anti-infective therapy (leung2019picaacommon pages 2-3, leung2019picaacommon pages 3-4).
3. Function-based behavioral treatment: functional behavioral assessment/analysis followed by differential reinforcement, competing-stimulus approaches, response interruption/redirection or blocking, discrimination training, and caregiver generalization. Applied behavior analysis has the strongest disorder-specific empirical support, especially in ASD/ID, although evidence quality is mostly below RCT level. Candidate MAXO: behavioral therapy, applied behavior analysis, functional assessment (fields2021picaautismand pages 6-8).
4. Psychological/psychiatric care: CBT may be useful in cognitively able patients; treat comorbid OCD, psychosis, depression, or anxiety for their own indications. Antipsychotics, SSRIs, or other drugs should not be considered established pica pharmacotherapy.
5. Intervention for complications: endoscopic or surgical foreign-body/bezoar removal for obstruction, perforation, or non-passing hazardous objects. Candidate MAXO: diagnostic imaging, endoscopy, foreign-body removal, gastrointestinal surgery.

Pharmacogenomics, gene therapy, cell therapy, RNA therapeutics, targeted molecular therapy, and immunotherapy are not applicable based on current evidence.

13. Prevention

• Primary: adequate maternal/child nutrition; prevention and early treatment of iron deficiency; lead-safe housing; sanitation; safe storage/removal of ingestible hazards; developmentally appropriate enrichment and supervision.
• Secondary: ask directly about non-food ingestion in pregnancy, unexplained iron deficiency, ASD/ID, and recurrent abdominal/toxicologic presentations. Fields et al. recommend caregiver monitoring, restricting access, childproof locks, occupying activities, and communication among caregivers (fields2021picaautismand pages 6-8).
• Tertiary: repeated exposure review, laboratory monitoring where indicated, behavioral relapse plans, school/home coordination, and rapid evaluation of abdominal pain, vomiting, choking, or neurologic change.

Vaccination, antimicrobial prophylaxis, preimplantation testing, prenatal genetic diagnosis, carrier screening, and cascade genetic screening are not pica-prevention strategies.

14. Other species and natural disease

Pica-like or “depraved appetite” behavior occurs in cattle, dogs, cats, and other animals, often in association with nutritional imbalance, gastrointestinal disease, boredom, or behavioral disturbance. These are veterinary behavioral signs, not proof of a naturally occurring homolog of the human DSM/ICD psychiatric disorder. No pica-specific orthologous gene, breed ontology association, zoonotic transmission, or cross-species infectious mechanism is established. Human pica is not zoonotic.

15. Model organisms

No standardized mouse, rat, zebrafish, Drosophila, C. elegans, cell-line, organoid, iPSC, knockout, knock-in, transgenic, or humanized model recapitulates the complete human pica syndrome. Experimental consumption of kaolin by rodents is widely used as a proxy for nausea because rodents do not vomit; it should not be treated as a validated model of psychiatric pica. Relevant mechanisms are therefore studied indirectly through iron-deficiency models, sensory/reward paradigms, neurodevelopmental models, and behavioral reinforcement experiments. These models cannot reproduce the human developmental and cultural diagnostic exclusions.

Evidence interpretation and current research gaps

The 2024 ALSPAC study is the major recent advance because it supplies repeated community-cohort measurements rather than only severe clinical cases. Its abstract reports: “A total of 312 parents (3.08%) reported pica behaviors in their child” and “19.55% reported pica at least at two waves.” It also concludes that children with DD or autism may benefit from screening between 36 and 115 months (https://doi.org/10.1002/eat.24111; December 2024 publication metadata) (papini2024prevalenceandrecurrence pages 1-3).

Fields et al. provide the strongest large preschool ASD/DD comparison. Their abstract reports that, versus 3.5% in population controls, prevalence was “23.2%” in ASD and “8.4%” in DD, reaching “28.1%” in ASD with ID (https://doi.org/10.1542/peds.2020-0462; February 2021) (fields2021picaautismand pages 4-6, fields2021picaautismand pages 1-3).

Major unresolved questions are: whether and how iron deficiency causes pica; development of validated multi-item diagnostic instruments; prospective adult and pregnancy trajectories; representative incidence and remission estimates; comparative effectiveness trials of behavioral components; standardized patient/caregiver quality-of-life measures; and molecular studies designed specifically around rigorously diagnosed pica. Current evidence does not support a pica-specific gene, protein, pathway, omics classifier, drug target, or animal model.

References

1. (papini2024prevalenceandrecurrence pages 1-3): Natalie M. Papini, Cynthia M. Bulik, Samuel J. R. A. Chawner, and Nadia Micali. Prevalence and recurrence of pica behaviors in early childhood within the alspac birth cohort. The International journal of eating disorders, 57:400-409, Dec 2024. URL: https://doi.org/10.1002/eat.24111, doi:10.1002/eat.24111. This article has 24 citations.

2. (papini2024prevalenceandrecurrence pages 11-13): Natalie M. Papini, Cynthia M. Bulik, Samuel J. R. A. Chawner, and Nadia Micali. Prevalence and recurrence of pica behaviors in early childhood within the alspac birth cohort. The International journal of eating disorders, 57:400-409, Dec 2024. URL: https://doi.org/10.1002/eat.24111, doi:10.1002/eat.24111. This article has 24 citations.

3. (papini2023prevalenceandrecurrence pages 7-11): Natalie M. Papini, Cynthia M. Bulik, Samuel JRA Chawner, and Nadia Micali. Prevalence and recurrence of pica behaviors in early childhood: findings from the alspac birth cohort. medRxiv, Jun 2023. URL: https://doi.org/10.1101/2023.06.04.23290951, doi:10.1101/2023.06.04.23290951. This article has 5 citations.

4. (leung2019picaacommon pages 3-4): Alexander K.C. Leung and Kam Lun Hon. Pica: a common condition that is commonly missed - an update review. Dec 2019. URL: https://doi.org/10.2174/1573396315666190313163530, doi:10.2174/1573396315666190313163530. This article has 114 citations and is from a peer-reviewed journal.

5. (fields2021picaautismand pages 4-6): Victoria L. Fields, Gnakub N. Soke, Ann Reynolds, Lin H. Tian, Lisa Wiggins, Matthew Maenner, Carolyn DiGuiseppi, Tanja V.E. Kral, Kristina Hightshoe, and Laura A. Schieve. Pica, autism, and other disabilities. Pediatrics, Feb 2021. URL: https://doi.org/10.1542/peds.2020-0462, doi:10.1542/peds.2020-0462. This article has 98 citations and is from a highest quality peer-reviewed journal.

6. (fields2021picaautismand pages 1-3): Victoria L. Fields, Gnakub N. Soke, Ann Reynolds, Lin H. Tian, Lisa Wiggins, Matthew Maenner, Carolyn DiGuiseppi, Tanja V.E. Kral, Kristina Hightshoe, and Laura A. Schieve. Pica, autism, and other disabilities. Pediatrics, Feb 2021. URL: https://doi.org/10.1542/peds.2020-0462, doi:10.1542/peds.2020-0462. This article has 98 citations and is from a highest quality peer-reviewed journal.

7. (leung2019picaacommon pages 2-3): Alexander K.C. Leung and Kam Lun Hon. Pica: a common condition that is commonly missed - an update review. Dec 2019. URL: https://doi.org/10.2174/1573396315666190313163530, doi:10.2174/1573396315666190313163530. This article has 114 citations and is from a peer-reviewed journal.

8. (fields2021picaautismand pages 6-8): Victoria L. Fields, Gnakub N. Soke, Ann Reynolds, Lin H. Tian, Lisa Wiggins, Matthew Maenner, Carolyn DiGuiseppi, Tanja V.E. Kral, Kristina Hightshoe, and Laura A. Schieve. Pica, autism, and other disabilities. Pediatrics, Feb 2021. URL: https://doi.org/10.1542/peds.2020-0462, doi:10.1542/peds.2020-0462. This article has 98 citations and is from a highest quality peer-reviewed journal.

9. (papini2024prevalenceandrecurrence pages 3-4): Natalie M. Papini, Cynthia M. Bulik, Samuel J. R. A. Chawner, and Nadia Micali. Prevalence and recurrence of pica behaviors in early childhood within the alspac birth cohort. The International journal of eating disorders, 57:400-409, Dec 2024. URL: https://doi.org/10.1002/eat.24111, doi:10.1002/eat.24111. This article has 24 citations.

10. (leung2019picaacommon pages 1-2): Alexander K.C. Leung and Kam Lun Hon. Pica: a common condition that is commonly missed - an update review. Dec 2019. URL: https://doi.org/10.2174/1573396315666190313163530, doi:10.2174/1573396315666190313163530. This article has 114 citations and is from a peer-reviewed journal.

11. (fields2021picaautismand pages 3-4): Victoria L. Fields, Gnakub N. Soke, Ann Reynolds, Lin H. Tian, Lisa Wiggins, Matthew Maenner, Carolyn DiGuiseppi, Tanja V.E. Kral, Kristina Hightshoe, and Laura A. Schieve. Pica, autism, and other disabilities. Pediatrics, Feb 2021. URL: https://doi.org/10.1542/peds.2020-0462, doi:10.1542/peds.2020-0462. This article has 98 citations and is from a highest quality peer-reviewed journal.

12. (papini2024prevalenceandrecurrence pages 10-11): Natalie M. Papini, Cynthia M. Bulik, Samuel J. R. A. Chawner, and Nadia Micali. Prevalence and recurrence of pica behaviors in early childhood within the alspac birth cohort. The International journal of eating disorders, 57:400-409, Dec 2024. URL: https://doi.org/10.1002/eat.24111, doi:10.1002/eat.24111. This article has 24 citations.

Artifacts

• Edison artifact artifact-00