The Etiology of Mental Retardation in Iraqi Children

1. Abstract Background: Mental retardation is a group of heterogeneous disorders associated with generalized developmental delay during infancy and early childhood, while impairment in cognitive functions and adaptive behaviors became generally apparent during pre-school and early school years depending on the severity of the condition. Little is known about the etiology of mental retardation in Iraq. The aim of this paper is to describe the etiology of mental retardation in a sample of Iraqi children. Patients and methods: During one-year period (February 2018 to February 2019), thirty-six patients with mental retardation (25 males and 11 females) were observed at the neuropsychiatry clinic at the Children Teaching hospital of Baghdad Medical City. Their ages ranged from two to seventeen years. Results: Eighteen patients (50%) had idiopathic mental retardation (11 males and 7 females). Seven patients (19%) had Down syndrome (5 males and 2 females). male patients had Beckwith Wiedemann syndrome, one an brother. Three males inborn errors of metabolism, each phenylketonuria, and Lesch Nyhan The Nyhan an older brother who died from the Six patients each one Prader-Labhart-Willi Sanjad Sakati Richardson Kirk Coffin Siris kernicterus, Bartter Pediatric Huntington girl had large ears. Brain CT-scan was available for two patients with idiopathic mental retardation and one patient with kernicterus and showed normal findings. Conclusion: The causes of mental retardation in about two thirds of Iraqi patients with mental retardation were idiopathic mental retardation and Down syndrome.


Introduction
Mental retardation is a group of heterogeneous disorders associated with generalized developmental delay during infancy and early childhood, while impairment in cognitive functions and adaptive behaviors became generally apparent during pre-school and early school years depending on the severity of the condition.

Adaptive behaviors include
Daily living skills such as feeding self, dressing/undressing and using the bathroom.

Social skills and communication skills such as
understanding what is said.
Although the World Health Organization is still using the term mental retardation in its ICD-10 publication, the American Psychiatric Association has recently called the condition "Intellectual disability" [1,2].
Thomas Willis was the first doctor to describe mental retardation as a disease of the brain [1].

There are two main types of mental retardation
The syndromic mental retardation which is associated with other abnormalities caused by chromosomal and non-chromosomal genetic defects, endocrine disorders and inborn errors of metabolism.
Down syndrome (Trisomy 21) is the most common type of syndromic mental retardation and the most common chromosomal disorder in humans [8].
Prader-Labhart-Willi syndrome which is also called Prader-Willi syndrome is an other genetic syndrome that is associated with mental retardation. It can be caused by a deletion or disruption of genes in the proximal arm of chromosome 15 or by maternal disomy in the proximal arm of chromosome 15.
However, many patients with this genetic syndrome were found to have a normal karyotype [9].
Beckwith Wiedemann syndrome is an autosomal genetic syndrome that is associated with mental retardation [10].
Inborn errors of metabolism that commonly causes mental retardation include phenylketonuria, Homocystinuria and Lesch Nyhan syndrome [11].
Phenylketonuria is an autosomal recessive inborn error of metabolism caused by deficiency of phenylalanine hydroxylase which causes accumulation of dietary phenylalanine to potentially toxic levels.
Homocystinuria is another an autosomal recessive inborn error of metabolism associated with mental retardation. It is caused by deficiency of cystathionine beta synthase deficiency or CBS deficiency.
Lesch Nyhan syndrome is an X-linked inborn error of purine metabolism associated with mental retardation.
It is caused by deficiency of hypoxanthine-guanine phosphoribosyl transferase enzyme which is normally present in each cell in the body, but its highest concentration is in the brain, especially in the basal ganglia [11].
Other rare causes of mental retardation include Sanjad  Brain CT-scan was available for two patients with idiopathic mental retardation and one patient with kernicterus and showed normal findings.

Results
Eighteen patients (50%) had idiopathic mental retardation, eleven of them were males and seven      He was social, but hyperactive and liked to scribble.
He copies a line but couldn't copy a circle.      One male patient had Kernicterus.
One female patient had Bartter syndrome with low set ears.
One male patient had Pediatric Huntington disease, this patient was the older one, aged 17 years and the only one who died.

Discussion
Mental retardation is a complex heterogeneous