Table 1.

Review of Select Specific NDDs^a Associated with Self-Injurious Behaviors^b

NDD	Etiology	Clinical Characteristics	Prevalence	Incidence of SIBsc	Specific SIBsc
Smith-Magenis Syndrome1,9	Usually caused by deletions in the 17p11.2 region; a mutation in the RAI1 gene is associated with SIBs	Brachycephaly, midface hypoplasia, hoarse voice, speech delay, psychomotor and growth delay, cutaneous feature, behavior problems, hypotonia	1:15,000-1:25,000 live births	Nearly 100% of patients will have SIB	– Biting – Hitting – Picking at fingernails and toenails – Insertion of foreign objects into orifices
Lesch-Nyhan Syndrome,10	Mutation in hypoxanthine-guanine phosphoribosyl-transferase 1 (HPRTd)	Hyperuricemia, choreoathetoid movement, intellectual disability, aggression towards others	1:380,000 live births	When <1.5% HPRT enzyme is present, nearly 100% of patients will have SIB	– Lip biting – Finger biting – Head banging – Banging of arms and legs
Cri du Chat Syndrome1	Deletion on chromosome 5p	Cat like cry, intellectual disability, limited language development, sleep disturbances, hypersensitivity to auditory stimuli, vomiting-rumination	1:15,000-1:50,000 live births	76.8%-92%	– Head hitting – Scratching – Self-biting
Prader-Willi Syndrome11-14	Deletion of paternal 15q11-q13 region of chromosome 15	Hypotonia, intellectual delay, hypogonadism, dysmorphic features, short stature, obesity, behavioral and psychiatric manifestations	1:15,000 live births	70%-90%	– Skin picking – Nail biting – Hair pulling
Pervasive Developmental Disorders (ASDe, Asperger’s Disorder, Disintegrative Disorder, Pervasive Developmental Disorder not otherwise specified)2,15-19	Exact etiology unknown; combination of genetic, environmental, and neurobiological factors	Poor communication, social deficits, restrictive and stereotyped behaviors, hyperactivity, behavioral problems, tantrums, irritability, aggression	1:5919 individuals (ASD)	33%-71%	– Hitting – Self-biting
Fragile X Syndrome20-22	A single gene mutation on the X chromosome disrupts production of the fragile × mental retardation protein, which regulates the production of proteins needed for maturation and elimination of synapses during brain development	Neurobehavioral phenotype with associated cognitive delay, aggression, impulsivity, anxiety	1:8000 females and 1: 4000 males	17%-70%	– Self-biting – Rubbing – Scratching
Rett Syndrome23-25	Loss-of function mutations in the X-linked MECP2 gene, which leads to abnormal brain development and function	Stunted head growth, loss of acquired verbal skills, repetitive hand movements, ataxia, intellectual disabilities, and autistic-like behaviors	Females only, 1:10,000 live births	50%	– Mouth hitting
Cornelia de Lange Syndrome26-28	De novo mutations in cohesion complex genes, such as the nipped-B-like-gene (NIPBL), which affect the protein network that regulates separation of chromatins during cell division	Multiple behavioral and developmental symptoms, abnormal limb development, growth delay, cardiac and genitourinary anomalies, myopia, hirsutism, sleep disturbance, and hearing loss	1:10,000 – 1:30,000 live births	40%	– Face hitting (most classic) – Self-biting – Skin picking
Down Syndrome25	Attainment of extra copy of chromosome 21	Dysmorphic features, congenital malformations, endocrine disorders, obesity, hearing loss	1 in 700 live births	15%	– Eye poking

^aThe disorders highlighted in this table were chosen for two primary reasons: (i1) these disorders may be encountered by clinicians caring for children and youth with special healthcare needs (CSHCN) and (ii) published data exist pertaining to SIBs in these specific NDDs.

^bNDDs are presented in order of descending incidence of SIBs.

^cSelf-injurious behaviors

^dHypoxanthine-guanine phosphoribosyl-transferase 1

^eAutism Spectrum Disorders,