Syndromes associated with mental deficiency follow below classifications:

1. Chromosomal aberrations

  • Autosomal (on other chromosomes than the sexual ones): Down syndrome
     severe and profound mental deficiency (but verbally and paraverbally communicative despite the low level of language, with positive affect and pronounced attachment)
     anatomical-morphological anomalies, present at birth and accentuated with age; their physiognomy makes them look alike: in children, the skull is small (microcephaly), round face, flat forehead, not embossed and wide, eyes at a greater distance between them, small eyeballs, thick and wide nose, teeth appear late, anarchic, uneven, the lips, especially the lower one, are thickened and often transversely cracked; Small, asymmetrical, unlobed ears, short and thick neck, short upper and lower limbs (stature hypertrophy).
     Lack of independence in work, low level of thinking, poor coordination of movements, but with great imitating abilities.
     Etiological initiatives refer to the advanced age of one of the parents (over 45 years at birth), damaged reproductive organs, or gestational factors such as: long-lasting and strong emotions, physical fatigue, mechanical trauma or some infectious diseases, can cause Down syndrome.
  • Gonosomal (on sexual chromosomes):
     Turner syndrome: abnormalities in secondary sex characteristics in boys through the appearance of secondary female characters; Mental disorders are important and constant (the more x chromosomes, the more affected the intellect). Clinical differences in childhood and puberty but with aspects such as: wide hips as in women, gynecomastia, poorly developed hair, much atrophied genital organs; reduced sexual potency; absent libido; the presence of some forms of abnormal erotic manifestations.
     Klinefelter syndrome: occurs in girls, manifested by ovarian anomalies and dwarfism and anomalies in secondary sex characteristics. Mental deficiency most often mild or moderate.
     Hermaphrodism: syndrome of intersexuality, the presence in the same individual of male and female gonads, more or less abnormal and non-functional. The proportion of mentally retarded hermaphrodites is unknown.

2. Metabolic (metabolic heredopathies):

  • Phenylpyruvic oligophrenia (phenylketonuria):
     the absence of an enzyme that transforms phenylalanine into thyroxine (thyroid hormone) and in the absence of which phenylalanine accumulates in the blood, having a toxic character.
     Phenylpyruvic acid is easily detected in the urine of children and the early application of a diet without phenylalanine prevents the appearance of mental deficiency. It can be discontinued after a certain age.
     morphological peculiarities: light blue eyes, fine and sensitive skin, blond hair; delay in psychomotor acquisitions; motor stereotypes; changes in muscle tone up to stiffness; it is generally accepted that phenylpyruvic oligophrenia is hereditary.
  • Hartnup syndrome
     Hyperamino acids and increase in tryptophan excretion.
     skin lesions (pelagroid rash), photosensitivity, neuropsychic disorders (cerebellar ataxia, intentional tremor nystagmus), psychiatric conditions and mental deficiency.
  • Hepatolenticular degeneration
     disorder of copper metabolism (cupric thesaurism)
    hepatic symptoms (jaundice, hepatosplenomegaly); neurological symptoms of extrapyramidal type (intentional tremor, akinesia, convulsions, dysarthria); mental disorders (of behavior, of attention, agraphia, alexia, intellectual deficit).
  • Galactosemia (galactosuria)
     the lack of an enzyme necessary in the metabolism of galactose.
     The child appears normal at birth, but as soon as it is fed with milk, vomiting, jaundice and symptoms of malnutrition appear.
     Somato-weight and psychomotor development is slowed down, and intellectual deficit appears in mental development.
     Diagnosis – finding the increased amount of galactose.
     The administration of an early and long-term diet, which consists in excluding milk from the diet, prevents later normal development.
     recessive hereditary transmission, as several cases occur within the same family.
  • Fructosuria
     fructose metabolism disorder.
     The child develops normally until fruit juice is introduced into the diet, after which drowsiness, convulsive states are observed, and if the fruit diet is not interrupted, the child does not develop normally.
  • Amaurotic idiocies (Tay-Sachs form and Spielmayer-Voght form)
     lipid metabolism disorder and in these cases mental deficiency is accompanied by the deposition of various lipids at the level of the central and peripheral nervous system and at the level of the blood vessels.
     the child appears normal at birth, but after 3-6 months he becomes extremely apathetic and motor skills do not develop (does not raise his head, does not turn from side to side, is not able to grasp objects). Physiological and mental disorders, paralysis and convulsions also occur. Particularly symptomatic is the child’s hypersensitivity to light and noise.
     In these cases, the mental deficiency gradually becomes more and more obvious.
     The basic manifestation, which allows the differential diagnosis, is the gradual degradation of vision up to blindness and pathological changes of the fundus.
     it is hereditary, as it occurs in several generations.
  • Niemann Pick disease
     Niemann Pick cells appear (20-90 micron reticulated cells, 2-3 nuclei, foamy cytoplasm due to lipid accumulation)
     in the first months of life, the general condition worsens, digestive disorders (anorexia, vomiting, diarrhea), increase in volume of the abdomen due to hepatosplenomegaly, pigmentation of the integuments and sometimes also of the mucous membranes.
     Neuropsychiatric disorders have a progressive character and consist of muscle hypotonia, decreased visual acuity up to blindness, decreased hearing up to deafness and mental deterioration that can reach the degree of profound mental deficiency.
     The laboratory examination reveals: normal acid phosphatases; moderately increased lipidemia due to cholesterol, phospholipids and triglycerides.
  • Gaucher disease (cerebrosidosis or lipidosis with cerebrosides)
     early disorders marked by stunted growth, splenomegaly, neurological disorders (somnolence, spasticity, serious respiratory disorders) and evolution towards death, and in the juvenile form it has a slow evolution in which the neurological signs appear progressively and consist mainly of seizures, EEG alterations , mental impairment.
  • Hurler disease
     important amounts of acid mucopolysaccharides
     grotesque, coarse features, with a bulging forehead, the root of the nose erased, wide nostrils, thick lips, rough and bushy hair, voluminous tongue and small teeth. The trunk is deformed, with increased antero-posterior diameter and dorso-lumbar kyphosis. The appearance of the limbs is characteristic: they are ‘stuffy’, limited joint movements, extension of the elbows and knees.
     The voice is hoarse and the breathing is noisy. They look dwarfish and are mentally retarded.

3. Dysostotic forms of mental deficiency:

  • Arachnodactyly:
     very long and thin fingers on the hands and feet, deep chest, narrow skull, frequent congenital abnormalities of the heart, lens, spine (scoliosis, kyphosis);
     early mental deficiency, but it is not always serious.
  • Gargoyleism:
     Elderly appearance, subnormal stature, with very short neck and limbs, reduced mobility of the joints, heavy gait, movements without flexibility.
     Enlarged skull, sax-shaped nose, large mouth, thick tongue and lips, opacities may appear on the cornea, different degrees of mental deficiency
     umbilical hernia and protuberant abdomen (very enlarged liver and spleen).
  • Microcephaly:
     exogenous (prenatal factors, brain injuries from birth)
     endogenous (exaggeratedly small skull, conical shape, beveled forehead)
     anomalies in the structure of the nervous system with serious mental deficiency
     great ability to imitate, very lively movements, developed affectivity
  • Hypertelorism: It is a rare form characterized by the fact that the distance between the eyes is excessively large. in some extreme cases the eyes are placed on the external parts of the face. The skull is brachycephalic and shows anomalies of the palatine vault.
  • Apert syndrome (acroencephalosyndactyly):
     specific cranio-facial appearance, tower-shaped skull, distant orbits and obliquely downwards, large and crooked nose (parrot)
     syndactyly, polydactyly, widening of the thumb and eye abnormalities (cataract, optic atrophy, nystagmus). in general, the mental deficiency is not serious.
  • Hydrocephalus (congenital or acquired)
     accumulation of cerebrospinal fluid in the skull and increased pressure in the cerebral ventricular system
     Occlusive hydrocephalus: blockage of the cerebrospinal fluid, due to obstructions at the level of the foramen Monro, the appendage of Sylvius or the foramen Magendie.
     Aresorptive hydrocephalus: prevention of cerebrospinal fluid resorption
     bulging forehead; wide fontanelles; the eyes are lowered and the iris is half covered by the lower eyelid
     variable motor disabilities; convulsive or epileptic seizures; walking and speaking appear late and remain defective, variable degree of deficiency

4. Xerodermic forms of mental deficiency: Van Bogaert (1936)

  • Rud syndrome:
     hereditary transmitted syndrome (frequent in cases of consanguinity), serious mental deficiency, additionally ichthyosis, epilepsy, infantilism evident after birth.
     The skin of these children is dry, yellow-gray in color and covered with scales that fall off easily (ichthyosis), and their hair grows very hard.
    o Sturge-Weber syndrome:
     different degrees of mental deficiency and reddish or purple spots on the skin (angiomatosis)
     condition accompanied by epileptic seizures, aphasia, hemiparesis, mono/hemiplegia.
    o Bourneville tuberous sclerosis:
     mental deficiency accompanied by epilepsy, reddish-yellow or black color.
     sclerotic nodules in the cortex and sebaceous adenomas on both sides of the nose (butterfly wings, Pringle’s butterfly);
     Mental deficiency is present at birth and progresses with age, going up to profound mental deficiency (vegetative idiot).

5. Endocrine:

  • Hypothyroidism:
     endemic cretinism: insufficient concentration of iodine in soil and water that affects the synthesis of thyroid hormones in the mother’s body (intrauterine)
     sporadic cretinism: underdevelopment/degeneration of the thyroid glands
     cretins have a below normal stature, large skull, yellowish and dry skin, coarse hair, are apathetic, have a reduced reactivity to environmental stimuli, movements and mimicry are reduced.
     the administration of thyroid preparations accompanied by vitamin B, lead to psychological and somatic improvements when they are detected early
  1. Mental deficiency associated with neurological disorders:
    o Marinescu-Stögren syndrome:
     spinocerebellar ataxia: involuntary movements, tremors, balance disorders, muscle hypotonia, ocular, skeletal, genital abnormalities
     Mild to profound mental deficiency, manifested late
    o Oligophrenias: underdevelopment of some regions of the brain, behavioral disorders
    o Cerebral palsy: pronounced disproportion between the level of development of different mental functions, mild deficiency

To address some of these syndromes, different therapies have great results, follow below article for more information: Play and recovery in mental deficiency

Donders J., Hunter S., (2018), Intellectual Disability Syndromes, Neuropsychological Conditions across the Lifespan, Cambridge University Press, pg 61-78

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