True: Learning disability is marginally more common in males (Fraser & Kerr 2003, p. 27).

True: Although sociocultural influences are important, biological factors have been underplayed in the past. Up to 45% of those with mild LD may have definite organic factors including subtle chromosomal abnormalities and perinatal insults from toxins such as alcohol. However, physical causes are found in 55–75% of cases of severe LD (Gelder et al 2006, p. 713; Johnstone et al 2004, p. 530).

True: About 70% of cases of Angelman syndrome are due to a microdeletion on the long arm of the maternally derived chromosome 15 (15q11-13).

About 70% of Prader–Willi syndrome cases are due to a microdeletion at exactly the same point of the paternally derived chromosome 15.

The other mechanisms include Uni Parental Disomy (maternal UPD for Prader–Willi and paternal UPD for Angelman) and imprinting centre errors (Gelder et al 2000, p. 1958; Johnstone et al 2004, pp. 557, 805).

False: Both DSM-IV and ICD-10 require normal cognitive function for the diagnosis of Asperger syndrome.

True: There are a number of similarities between the two syndromes including speech deficits, repetitive and stereotyped behaviour, preference for rigid routines and rigid thinking. The degree of these autistic traits depends on the degree of cognitive disability.

Children with Cornelia De Lange syndrome show characteristic features of hypertricosis, e.g. hirsutism, synophrys and long eyelashes. The facial abnormalities include depressed nasal bridge, ocular abnormalities, prominent philtrum, thin lips, anteverted nostrils, down-turned angle of mouth, bluish tinge around the eyes, widely spaced teeth, high arched palate, low set ears, micrognathia and short neck (Gelder et al 2000, p. 1957).

False: 75–85% of chromosomal disjunctions are of maternal origin. The extra chromosome in trisomy 21 is maternal in over 90% of cases (Johnstone et al 2004, p. 539).

False: In general, the Down’s syndrome population has an IQ range of 20–55, i.e. severe to moderate LD. Those with a translocation and Trisomy 21 tend to have moderate to severe intellectual deficits. 1–3% show Mosaicism and may have normal intelligence and achievement (Gelder et al 2006, p. 717).

True: Prevalence of Alzheimer’s increases with age:

Females have an earlier age of onset than males. The duration of dementia is approximately 6 years (Fraser & Kerr 2003, p. 274).

False: Down’s syndrome is characterized by hypotonia and hyperextensibility of joints (Gelder et al 2006, p. 717).

True: Fragile X syndrome affects approximately 1 in 4425 to 6045 males and causes LD in 1 in 8000 females. While Fragile X syndrome is the most common inherited cause of LD, Down’s syndrome is the most common cause of LD overall (Gelder et al 2000, p. 1953).

False: The abnormalities of speech include perseveration of words and phrases, echolalia, palilalia, ‘cluttering’, narrative speech, comprehension difficulties with high association compounds, productive semantic errors and speech sound substitution difficulties. Syntactic competency and semantic concepts remain intact in Fragile X males (Gelder et al 2000, p. 1954).

False: Galactosaemia is an autosomal recessive condition caused by the absence of galactose-1-phosphate uridyl transferase. This results in intracellular accumulation of galactose-1-phosphate which is highly toxic. The incidence is 1/60 000 in the UK. Affected infants are normal at birth. On exposure to dietary galactose they develop jaundice, vomiting, diarrhoea, failure to thrive, psychomotor retardation, hepatosplenomegaly, renal disease, cataracts, increased susceptibility to infection, hypoglycaemia, galactosaemia, galactosuria and aminoaciduria (Fanconi syndrome) (www.Gpnotebook.co.uk).

False: Hunter’s syndrome is an X-linked mucopolysaccharide disorder. There is no generally accepted effective treatment for mucopolysaccharidoses. Bone marrow transplant has been suggested but remains mostly experimental (Gelder et al 2000, p. 1959; Harris 2000, p. 358).

True: Mitral valve prolapse occurs in 55% of patients. Varicose veins occur in 20–40%. The prevalence of venous ulcers is 10–20 times higher than the general population. The risk of deep vein thrombosis and pulmonary embolism is increased (Craft et al 1985, p. 126).

True: Lesch–Nyhan syndrome is a sex-linked recessive disorder. It is extremely rare in females. The usual mode of inheritance is from a carrier mother to her son who is affected (Gelder et al 2000, p. 1956; Sadock & Sadock 2005, p. 2053).

True: Neurofibromatosis is an autosomal dominant disorder characterized by café-au-lait spots and tumours arising from neural crest tissue. Neurofibromatosis 1, the commoner form, is characterized by neurofibromas, gliomas and hamartomas of the eye and optic pathways, bone dysplasisa, LD in about 50%, hyperactivity and other behaviour disorders. The gene has been located to chromosome 17.

Neurofibromatosis 2 is characterized by bilateral vestibular schwannomas, other tumours such as meningiomas and ependymomas, and cataracts. The gene has been located to chromosome 22 (Craft et al 1985, p. 114; Gelder et al 2000, p. 1151).

False: Phenylketonuria is detected by routine screening of neonates using the Guthrie test or capillary blood phenylalanine estimation. Blood phenylalanine level >20 mg/dL and the presence of phenylpyruvic acid and its metabolites in urine confirm the diagnosis (Gelder et al 2000, p. 1959; Harris 2000, p. 335; Johnstone et al 2004, p. 527).

True: Rett syndrome almost exclusively affects females because the male fetuses tend to die in the womb. 80% of cases are due to sporadic mutations in the gene MECP2 at X q28 (Gelder et al 2000, p. 1955; Johnstone et al 2004, p. 553).

False: Tay–Sachs disease is an autosomal recessive disorder resulting in increased lipid storage. It is a rare disease except in the Ashkanazi Jews. About 1:30 of them are heterozygous for the gene, compared with 1:300 in other populations. Genetic screening permits preconceptual counselling (Craft et al 1985, p. 95; Fraser & Kerr 2003, p. 37).

True: Tuberous sclerosis complex is an autosomal dominant disorder. Symptoms include sleep problems, hyperactivity, aggression, self-injury and a non-compliant obsessiveness. It has a strong association with autism, the prevalence being 200 times more common than in the general population (Fraser & Kerr 2003, p. 89; Gelder et al 2000, p. 1151).

True: West syndrome consists of the triad of infantile spasms, severe learning disability and hypsarrhythmia. Causes of West syndrome include perinatal hypoxia (the most common), tuberous sclerosis, other congenital brain malformations, Down’s syndrome, phenylketonuria, leucodystrophy and various inborn errors of metabolism (Lishman 1997, p. 242).

True: Williams syndrome is associated with loquaciousness (talkativeness or chattiness), good verbal ability and a sociable manner. They tend to approach others spontaneously. This may mask their severe visuospatial and motor deficits. Autistic features are rare (Johnstone et al 2004, p. 555).

False: Males with XYY have tall stature and an IQ very slightly below average. They also have behavioural features which may increase the likelihood of antisocial acts (Fraser & Kerr 2003, p. 89; Gelder et al 2000, p. 1861; Johnstone et al 2004, p. 548).

True: Because of their limited cerebral, cognitive, metabolic and other reserves, people with learning disabilities are predisposed to decompensate and become delirious in the face of a variety of physiological and psychological stressors (Fraser & Kerr 2003, p. 223; Gelder et al 2006, p. 710).

True: Normalization theory is based on the principle that people with learning disabilities should be valued citizens with rights to dignity, growth and development. They should have accommodation and care that provides them with the same lifestyle and opportunities as the rest of the population. It aims to reverse the devaluation of the disabled person and the group while accepting that disability exists. Wolfensberger in 1972 called this ‘social role valorization’ (Fraser & Kerr 2003, p. 2; Gelder et al 2000, p. 1503).