Atrial septal defect (ASD) is an incomplete septation of atria in human heart causing circulatory problems. Its frequency is estimated at one per 10 000. Actions of numerous genes have been linked to heart development. However, no single gene defect causing ASD has yet been identified. Incomplete heart septation similar to ASD was reported in transgenic mice with both inactive alleles of gene encoding mammalian zinc metalloprotease a mammalian tolloid-like 1 (tll1). Here, we have screened 19 ASD patients and 15 healthy age-matched individuals for mutations in TLL1 gene. All 22 exons were analyzed exon by exon for heteroduplex formation. Subsequently, DNA fragments forming heteroduplexes were sequenced. In four nonrelated patients, three missense mutations in coding sequence, and one single base change in the 5 0 UTR have been detected. Two mutations (Met182Leu, and Ala238Val) were detected in ASD patients with the same clinical phenotype. As the second mutation locates immediately upstream of the catalytic zinc-binding signature, it might change the enzyme substrate specificity. The third change, Leu627Val in the CUB3 domain, has been found in an ASD patient with interatrial septum aneurysm in addition to ASD. The CUB3 domain is important for substrate-specific recognition. In the remaining 15 patients as well as in 15 reference samples numerous base substitutions, deletions, and insertions have been detected, but no mutations changing the coding sequence have been found. Lack of mutations in relation to ASD of these patients could possibly be because of genetic heterogeneity of the syndrome.

Fragile X syndrome (FXS) is the most common form of familial mental retardation and one of the leading known causes of autism. The mutation responsible for FXS is a large expansion of the CGG repeats in the promoter region of the FMR1 gene resulting in the transcriptional silencing of the gene in the pathophysiology of Fragile X syndrome was hypothesized. 23 male patients affected by Fragile X syndrome (full mutation in the FMR1 gene) and 24 controls were included in the study. The serum levels of HDL-C were lower in FXS patients (p < 0.001). The serum levels triacylglycerols were higher in FXS patients (p = 0.007) Further study involving larger samples are necessary to confirm the results and define the health implications for abnormal lipid levels in FXS patients.

X‐linked mental retardation (XLMR) refers to a group of inherited disorders characterised by varying degrees of mental retardation, caused by mutations in various genes present on the X‐chromosome. Historically, XLMR is divided into syndromic (MRXS) and nonsyndromic (MRX). At least 209 different XLMR disorders have been described including 143 forms of syndromic mental retardation. Fragile X syndrome is the most frequent syndrome and most studied XLMR syndrome. It is now possible to identify 42% of the genetic defects in XLMR families with obligate female carriers. Most of the mutated genes in XLMR are thought to influence development, cell migration, formation and maintenance of neural networks and cell‐to‐cell communication in brain. Thus the diagnosis of mental retardation in a child has an enormous impact in most affected families. Genetic counselling is strongly recommended to family members. Key Concepts: X‐linked mental retardation (XLMR) is a very heterogeneous set of conditions responsible for a large proportion of inherited mental retardation. XLMR can be divided into syndromic (MRXS) and nonsyndromic (MRX). Genes involved in XLMR influence development, cell migration, formation and maintenance of neural networks and cell‐to‐cell communication in brain. Mental retardation phenotype can emerge as the final common pathway of many different types of abnormal cellular processing. Genetic counselling is an important part in general management in the case of mental retardation.

Fragile X syndrome (FXS) is the most common form of familial mental retardation and one of the leading known causes of autism. The mutation responsible for FXS is a large expansion of the CGG repeats in the promoter region of the FMR1 gene, resulting in the transcriptional silencing of the gene. Leptin may be considered a cytokine-like hormone with pleiotropic actions since it may be involved in the regulation of neuroendocrine functions and the immune system response, in addition to playing a role in development. Leptin and adiponectin may act in parallel as opposing metabolic counterparts. The involvement of leptin and adiponectin in the pathophysiology of FXS was hypothesized. Material and Methods: Twenty-three male patients affected by FXS (full mutation in the FMR1 gene) and 24 controls were included in the study. Plasma leptin and adiponectin levels were measured by the ELISA method using commercially available kits. Results: Adiponectin levels in FXS patients were significantly lower than those found in controls (p < 0.04). Leptin levels in FXS patients were significantly higher than those found in controls (p = 0.03). Conclusion: Adipokines may be involved in the psychiatric features observed in FXS patients. Further investigations are necessary to evaluate the role of adiponectin and leptin in FXS.