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Health supervision for children with Down syndrome. American Academy of Pediatrics Committee on Genetics. Health supervision for children with fragile X syndrome. American Academy of Pediatrics Committeeon Genetics. Hayes A, Batshaw M. Down syndrome. Primary care of adults with mental retardation. J Fam Pract. Z Kinderchir. This content is owned by the AAFP. A person viewing it online may make one printout of the material and may use that printout only for his or her personal, non-commercial reference.
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Navigate this Article. Function at one half to two thirds of CA IQ: 50 to Function at one third to one half of CA IQ: 35 to Function at one fifth to one third of CA IQ: 20 to Noticeable delays, especially in speech. Marked and obvious delays; may walk late. Marked delays in all areas. May have no unusual physical signs. May have some unusual physical signs.
Congenital abnormalities often present. Can acquire practical skills. Can learn simple communication. May be taught daily routines and repetitive activities. Need close supervision. Useful reading and math skills up to grades 3 to 6 level. Can learn elementary health and safety habits. May be trained in simple self-care. Often need attendant care.
Can participate in simple activities and self-care. Need direction and supervision. May respond to regular physical activity and social stimulation. Can acquire vocational skills for self-maintenance. Can perform tasks in sheltered conditions. Not capable of self-care. Integrated into general society. Can travel alone to familiar places. Fetal alcohol syndrome. Alcohol consumption by mother during pregnancy.
May include retardation, behavior problems, ADHD, seizures, autism. Normal life expectancy; mild to profound MR. Behavioral phenotype may also aid diagnosis as course evolves. Cytogenetic studies; brain imaging; metabolic studies. Diagnostic techniques that may aid in diagnosis are constantly being refined. Magnetic resonance imaging of the brain. Cerebral palsy or motor asymmetry. Abnormal head size or shape.
Down's syndrome ; poor prenatal care; infections during pregnancy; abnormal delivery; illness during infancy; toxic substances e. Regardless of the cause, part of the definition of mental retardation is that it manifests itself during an individual's developmental period, usually deemed to be birth through age eighteen. Many psychiatrists argue that the age before which signs of retardation must become manifest should be raised from eighteen to twenty-two, to reflect the difficulties in obtaining accurate age records for many people with this disability and the differing rates at which people develop.
An ordinary adult cannot suddenly "become" mentally retarded. An adult may, for reasons related to accident or illness, suffer a catastrophic loss in intellectual functioning and adaptive skills, but this would not make him or her "mentally retarded," since by definition mental retardation starts during childhood.
One implication of this is that mental retardation is virtually impossible for an adult to fake: when evaluating whether an adult is mentally retarded, testers look not only at I. Early diagnosis can help the person with mental retardation obtain access to appropriate special education, training, clinical programs, and social services during important developmental years -- as well as through life. With help from family, social workers, teachers, and friends, many mentally retarded people succeed in simple jobs, maintain their own households, marry, and give birth to children of normal intelligence.
There is no "cure" for mental retardation. Characteristics and Significance of Mental Retardation. Although mental retardation of any degree has profound implications for a person's cognitive and social development, it is a condition which in many cases is not readily apparent. While some of the mentally retarded, such as those whose retardation is caused by Down's syndrome or fetal alcohol syndrome, have characteristically distinctive facial features, most cannot be identified by their physical appearance alone.
Unless their cognitive impairment is unusually severe e. Many capital offenders with mental retardation did not have their condition diagnosed until trial or during post-conviction proceedings.
A person with mental retardation, according to one expert, "is always the least smart person in any group. This leads to fear, dependence and an experience of terrible stigma and devaluation.
They may wrap themselves in a "cloak of competence," hiding their disability even from those who want to help them, including their lawyers. At times, even competent lawyers who are anxious to help their clients may fail to identify their clients' retardation or may be unable to access funds for a psychological evaluation.
Cruz nonetheless insisted to reporters that, although he was perhaps "slow in reading, slow in learning," he was not mentally retarded. He had gone through much of his schooling allowing his younger sister to complete his homework for him. When he was given papers to read in connection to his case, he would carefully stare at them. If he was asked a substantive question, he usually responded, "I don't recall.
He lied about finishing high school. He was actually in special education classes and did not finish the sixth grade. He was drafted into the army and discharged because of his mental retardation. He lied about his service record. He often made things up so that people would not suspect mental retardation. The fact that many people with mental retardation can and do live relatively "normal" lives with their families or in the community, coupled with the fact that most of them do not look different from people with average intellectual capabilities, can make it difficult for the public to appreciate the significance of their condition.
But, as the late U. A person with mental retardation will have limitations of a greater or lesser extent in every aspect of cognitive functioning. He or she will have limited abilities to learn including reading, writing, and arithmetic and to reason, plan, understand, judge, and discriminate. Mental retardation truncates the capacity to think about intended actions, to consider their possible consequences, and to exercise restraint. One expert has summarized the attributes of mental retardation as follows:.
Almost uniformly, individuals with mental retardation have grave difficulties in language and communication. They have problems with attention, memory, intellectual rigidity, and in moral development or moral understanding. They are susceptible to suggestion and readily acquiesce to other adults or authority figures People with mental retardation have limited knowledge because their impaired intelligence has prevented them from learning very much. They also have grave problems in logic, foresight, planning, strategic thinking, and understanding consequences.
Many of these limitations, of course, characterize children. But while children will outgrow these limitations as their brains develop and mature, people with mental retardation will not.
In limiting a person's cognitive development and ability to learn, mental retardation also limits the ability to understand abstract concepts, including moral concepts. While most defendants with mental retardation who have committed a crime know they have done something wrong, they often cannot explain why the act was wrong. The inability to comprehend abstract concepts may include the inability to fully understand the meaning of "death" or "murder".
Before his execution, Mason asked one of his legal advisors for advice on what to wear to his funeral. At his clemency hearing, the chair of the Louisiana pardons board asked Sawyer if he knew what murder was.
Sawyer responded, "That's when the breath leaves your body. Since they often face abuse, taunts, and rejection because of their low intelligence, people with mental retardation can be desperate for approval and friendship. Eager to be accepted and eager to please, people with mental retardation are characteristically highly suggestible. Washington was so suggestible and eager to please, according to a former employer, that "you could get [him] to confess that he walked on the moon.
L ow intelligence and limited adaptive skills also mean that people with mental retardation often miss social "cues" that other adults understand. Their inappropriate social responses can be misinterpreted by people who do not know they have mental retardation or who do not understand the nature of retardation.
They may act in ways that seem suspicious, even when they have done nothing wrong. When questioned by police or other authority figures, they often smile inappropriately, fail to remain still when ordered to do so, or act agitated and furtive when they should be calm and polite.
Others may fall asleep at the wrong moment. Welcome has mental retardation and, according to psychiatric testimony presented at his trial, has a mental age of eight. He smiled incessantly during his capital murder trial, an almost involuntary defense mechanism developed in response to a lifetime of taunts.
As his defense attorney noted, "Many people with retardation smile a lot They are anxious for approval, and have learned that smiling is one way to get [it]. But they don't have the judgment to know when to smile. He was sentenced to death and remains today on death row.
Trial counsel were not aware that they had mental retardation. But their tendency to sleep peacefully during their trials helped alert post-conviction lawyers to their mental disability. In the case of White, who snored loudly during the penalty phase of his trial, the prosecutor argued that his conduct indicated his lack of remorse for his crime and his lack of respect for the criminal justice system.
Both Fairchild and White were sentenced to death and executed. Table 1. Causes of mental retardation in regards to development stage. Chromosomal abnormalities Autosomal chromosom aneuploidies Aberrations in autosomal chromosome number in live born babies are restricted to aneuploidies: trisomy 13 Patau's syndrome , 18 Edward's syndrome and trisomy 21 Down syndrome , monosomy of any autosomal chromosome being lethal in the earliest stages of embryonic life.
Down syndrome DS Down syndrome is the most frequent genetic cause of mental retardation. Cri du Chat syndrome Cri du Chat syndrome CdCS is caused by a deletion of variable size occurring on the short arm of chromosome 5 5p-.
Sex chromosomal aneuploidies Turner syndrome 45X0 Typically, genetic diagnosis of Turner syndrome had been done in adolescence, when puberty had fails to install. The level of intellectual deficit increases with the number of X chromosome, mental retardation being identified to individuals with more than four X Other extra sex chromosome phenotypes Clinical and developmental impact of a supernumerary sex chromosome led to the studies focused on establishing and recognising the physical and cognitive profiles of these disorders.
Clinical phenotype IQs range Behavioral phenotype 48,XXYY tall, with long legs underdeveloped genitalia , hypergonadotropichypogonadism , gynecomastia 60 to 80 higher risk for internalizing and externalizing symptoms; anxiety and withdrawal aggressive and delinquent behaviors 48,XXXY average to tall stature, facial dysmorphism: hypertelorism, flat nasal bridge, underdeveloped genitalia , hypergonadotropichypogonadism , gynecomastia 40 and 60 immaturity, passivity, with occasional irritability, temper tantrums, and outbursts 49,XXXXY microcephaly coarse face, ocular hypertelorism, flat nasal bridge, and upslanting palpebral fissures underdeveloped genitalia , hypergonadotropichypogonadism , 20 to Table 2.
Clinical and behavioral phenotype in supernumerary sex chromosome disorders. Contigous gene syndromes associated with cognitive deficits In contiguous gene syndromes, the disorder is due to microdeletions or microduplications of chromosomal segments associated with clusters of single gene disorders.
Angelman Syndrome AS Is a neurological disorder with a heterogeneous genetic causality. Miller-Dieker syndrome Miller-Dieker syndrome is characterized by lissencephaly and facial dysmorphy.
Monogenic mental retardation Studies looking at single genes that may contribute to intellectual disability were started by reports of numerous families in which intellectual disabilities were common and transmitted in Mendelian pattern. Table 3. Table 4. Mental retardation in metabolic disorders The evolution of metabolic disorders may disrupt development of children with previous normal development.
Variability in part due to variable numbers of affected mitochondria, and to the affected tissue, the most damaged cells of the brain, heart, liver, skeletal muscles, kidney and the endocrine and respiratory systems. The injury affect the white matter of the nervous system and is progressive, tends to get worse as the child gets older. Mutation causes abnormal enzyme function. Children develop hypotonia, seisures, hypotermia, developmental and grow delay.
Table 5. Metabolic diseases associated with MR or DD. Multifactorial inheritance and mental retardation A clinical phenotype is frequently the result of a complexity of interaction between different pathways including many genes, proteins and environmental factors.
Personal clinical history length of pregnancy, premature onset of labour or rupture of the membranes, duration and course of labour, type of delivery and any complications, Apgar scores at one and especially five minutes should be reviewed, and birth weight length and head circumference measurements obtained and plotted on appropriate growth charts illnesses, feeding or sleeping difficulties in the newborn period and problems with sucking or swallowing, temperament atypical course in child development seizures Documented medical situations from prior evaluations may offer an objective perspective for the professionals.
Dysmorphologic examination unusualcranio-facial, skeletal, palmar crease patterns. Most minor abnormalities are readily recognized even on cursory examination. For the physician it will be important to ask specific questions about the child's current developmental abilities at each visit. Neurologic examination -hypotonia, spasticity, ataxia - seizures - cerebral palsy An EEG can be obtained when a child with global developmental delay has a history or examination features suggesting the presence of epilepsy or a specific epileptic syndrome: Lennox-Gastaut syndrome, myoclonic epilepsy, Rett syndrome.
If available, MRI should be obtained in the presence of physical findings e. Endocrinologic examination -growth delay -obesity -genital abnormalities - clinical signs for hypotiroidy 7.
Other clinical examination cardiologist, orthopedicsurgeon, gynecologist, ophthalmologist, audiologist. Vision assessment can include vision screening and a full ophthalmologic examination visual acuity, extra-oculo-movements, funduscopic. Audiometric assessment can include behavioural audiometry or brainstem auditory evoked response testing when feasible.
Transient evoked otoacoustic emissions are used as screening studies in newborns. Metabolic testing testing amino and organic acids thyroid function IGF. Table 6. Clinical genetics evaluation of the child with suspicion of MR. More Print chapter. How to cite and reference Link to this chapter Copy to clipboard.
Available from:. Over 21, IntechOpen readers like this topic Help us write another book on this subject and reach those readers Suggest a book topic Books open for submissions. More statistics for editors and authors Login to your personal dashboard for more detailed statistics on your publications. Access personal reporting. More About Us. Environmental factors. Chromosomal abnormalities cytogenetic techniques. Trisomy 21 Partial trisomies e.
Cryptic chromosomal abnormalities complex methods. Mutation of a single gene. Complications of pregnancy Diseases in mother such as heart and kidney disease and diabetes Placental dysfunction. During delivery. Septicemia, severe jaundice, hypoglycemia. Postnatal in infancy and childhood. Traumatic, accidental, infectious. Brain infections such as tuberculosis, encephalitis, and bacterial meningitis Head injury Chronic lead exposure Severe and prolonged malnutrition Gross under stimulation.
MR that develops after a period of normal development. Lysosomal storage diseases Peroxizomal disorders Exposure to heavy metals, pesticide, malnutrition. Multifactorial or complex inheritance MR. Clinical phenotype. IQs range. Behavioral phenotype.
Protein function. Rubinstein—Taybi syndrome. Transcriptional coactivator similar to CBP, with potent histone acetyl transferase: chromatin-remodelling factor. ICF syndrome: immune deficiency associated with centromeric instability, facial dysmorphy and MR.
DNA methyltransferase 3B, involved in chromatin remodelling. Williams syndrome. Transcription factors, potential regulator of c-Fos and immediate-early gene expression. Nonsyndromic AR mental retardation. ATP-dependent protease; regulation of mitochondrial energy metabolism. Unknown function, protein contains C2 and DM14 domains. Angelman syndrome. Lissencephaly with cerebellar hypoplasia. Extracellular matrix ECM molecule, reelin pathway. Low-density lipoprotein receptor, reelin pathway. Protein o -mannosyltransferase 1 glycosylation of alpha-dystroglycan.
Walker—Warburg syndrome. Protein o -mannosyltransferase 2 glycosylation of alpha-dystroglycan. Muscle—eye—brain disease MEB.
Protein o -mannose beta-1,2-n-acetylglucosaminyltransferase. Fukuyama congenital muscular dystrophy FCMD with type 2 lissencephaly.
Homology with glycoprotein-modifying enzymes no biochemical activity has been reported. Microcephaly vera. Cell cycle control and DNA repair. Mitotic spindle function in embryonic neuroblasts. Formation of mitotic spindle during mitosis and meiosis. Localization to the spindle poles of mitotic cells. Clinical features. Facial anomalies, macroorchidism. X-linked adrenoleukodistrophy. Cognitive regression, spasticity, seeing loss, dementia, Addison disease. Membrane transporter, peroxisome.
MAO-A-deficiency behaviour. Lowe syndrome. Short stature, cataracts, hypotonia, aminoaciduria, progressive renal disease. Signal transduction, lipid metabolism.
Glycerol kinase deficiency. Short stature, spasticity, osteoporosis. Nuclear translocation of the hyperglycerolaemia glucocorticoid-receptor complex. Microcephaly, hypotonic facies, facial, urogenital and skeletal anomaliesthalassaemia, HbH inclusions, microcephaly, short stature, spastic diplegia. DNA helicase; chromatin remodelling, DNA methylation and regulation expression; regulator of cortical size. Aarskog—Scott syndrome.
Facial, digital and genital anomalies, short stature. RhoGEF; possible role in stimulation of actin polymerization. Coffin—Lowry syndrome. Facial and skeletal anomalies. Serine-threonine protein kinase; CREB phosphorilation; long term memory. Cerebellar hypoplasia or dysplasia. Epilepsy, cerebellar anomalies. Negative control of rhoGTPases; and epilepsy stabilization of dendritic arbours. Regression, epilepsy, acquired microcephaly, hand stereotypies, autism Hypotonia, apnea, epilepsy.
Transcriptional silencer of neuronal genes. Creatine deficiency syndrome. Creatine transporter, maintenance of phospho creatine pool in brain. Periventricular heterotopia Otopalatodigital syndrome I and II. Epilepsy, brain anomalies, short stature, cleft palate, facial and skeletal anomalies. Actin-binding protein; neuriteoutgrowth;dendritic spine formation. West syndrome Partington syndrome X-linkedlissencephaly, ambiguousgenitalia Proud syndrome. Infantile spasms, regression, epilepsy, dystonia Lissencephaly, corpus callosum agenesis, epilepsy, ambiguous genitalia, Microcephaly, corpus callosum agenesis, urogenital anomalies.
Infantile spasms. Serine-threonine kinase; chromatin remodelling. Epilepsy, macrocephaly, aggression. Synaptic-vesicle associated protein. Snyder—Robinson syndrome. Macrocephaly, palatal anomalies,scoliosis. Microcephaly, short stature, slender habitus, long face, congenital heart defect, cleft palate.
Polyglutamine-binding; mRNA splicing. Hypogonadism, obesity, facial anomalies, epilepsy. PHD zinc-finger protein; putative role in transcription. Thyroid and neurological abnormalities. Hypotonia, spasticity, dystonia, abnormal thyroid tests. Monocarboxylate transporter; T3 transport into the cytoplasm. Lenz microphthalmia. Microphthalmia, skeletal and urogenital anomalies. Transcriptional co-repressor; possible rolein modulation of histone acetylation and chromatin remodelling.
Siderius—Hamel cleft lip or palate syndrome. Microcephaly, spasticity, epilepsy, short stature, facial anomalies.
Microcephaly, spasticity, epilepsy, facial anomalies short stature,. Transcription factor;chromatin remodelling. Short stature, skeletal and facial abnormalities, hearing loss. Metabolism, glycosaminoglycan metabolism. Pelizaeus-Merzbacher syndrome. Nystagmus, truncalhypotonia and progressive spastic paraplegia, ataxia, and dystonia associated with CNS dysmyelination. Membrane component, myelin component. Choreoathetosis, self-mutilation, hyperuricemia.
Metabolism, purine ribonucleoside salvage. Opitz syndrome. Macrocephaly, facial anomalies, dysgenesis of corpus callosum, cardiac defects, hypotonia. Ubiquitin cycle, microtubule-associated complex.
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