Lujan-Fryns syndrome in the differential diagnosis of schizophrenia

Detection of Morphological Abnormalities in Schizophrenia: An Important Step to Identify Associated Genetic Disorders or Etiologic Subtypes

Current research suggests that alterations in neurodevelopmental processes, involving gene X environment interactions during key stages of brain development (prenatal period and adolescence), are a major risk for schizophrenia. First, epidemiological studies supporting a genetic contribution to schizophrenia are presented in this article, including family, twin, and adoption studies. Then, an extensive literature review on genetic disorders associated with schizophrenia is reviewed. These epidemiological findings and clinical observations led researchers to conduct studies on genetic associations in schizophrenia, and more specifically on genomics (CNV: copy-number variant, and SNP: single nucleotide polymorphism). The main structural (CNV) and sequence (SNP) variants found in individuals with schizophrenia are reported here. Evidence of genetic contributions to schizophrenia and current knowledge on genetic syndromes associated with this psychiatric disorder highlight the importance of a clinical genetic examination to detect minor physical anomalies in individuals with ultra-high risk of schizophrenia. Several dysmorphic features have been described in schizophrenia, especially in early onset schizophrenia, and can be viewed as neurodevelopmental markers of vulnerability. Early detection of individuals with neurodevelopmental abnormalities is a fundamental issue to develop prevention and diagnostic strategies, therapeutic intervention and follow-up, and to ascertain better the underlying mechanisms involved in the pathophysiology of schizophrenia.

De novo Mutations From Whole Exome Sequencing in Neurodevelopmental and Psychiatric Disorders: From Discovery to Application

Neurodevelopmental and psychiatric disorders are a highly disabling and heterogeneous group of developmental and mental disorders, resulting from complex interactions of genetic and environmental risk factors. The nature of multifactorial traits and the presence of comorbidity and polygenicity in these disorders present challenges in both disease risk identification and clinical diagnoses. The genetic component has been firmly established, but the identification of all the causative variants remains elusive. The development of next-generation sequencing, especially whole exome sequencing (WES), has greatly enriched our knowledge of the precise genetic alterations of human diseases, including brain-related disorders. In particular, the extensive usage of WES in research studies has uncovered the important contribution of de novo mutations (DNMs) to these disorders. Trio and quad familial WES are a particularly useful approach to discover DNMs. Here, we review the major WES studies in neurodevelopmental and psychiatric disorders and summarize how genes hit by discovered DNMs are shared among different disorders. Next, we discuss different integrative approaches utilized to interrogate DNMs and to identify biological pathways that may disrupt brain development and shed light on our understanding of the genetic architecture underlying these disorders. Lastly, we discuss the current state of the transition from WES research to its routine clinical application. This review will assist researchers and clinicians in the interpretation of variants obtained from WES studies, and highlights the need to develop consensus analytical protocols and validated lists of genes appropriate for clinical laboratory analysis, in order to reach the growing demands.

Lujan-Fryns Syndrome (LFS): A Unique Combination of Hypernasality, Marfanoid Body Habitus, and Neuropsychiatric Issues, Presenting as Acute-Onset Dysphagia

BACKGROUND

Lujan–Fryns syndrome (LFS) is an extremely rare, X-linked disorder, for which the full clinical spectrum is still unknown. Usually, it presents with neuropsychiatric problems such as learning disabilities and behavioral issues in a typical combination with marfanoid features. Often, there is a positive family history for the disorder. However, sporadic cases have also been reported in males. More interestingly, there is no case of LFS presenting with acute-onset dysphagia in the English language medical literature.

CASE PRESENTATION

A 17-year-old Pakistani mentally normal school boy was admitted for the workup of acute-onset dysphagia, hypernasal speech, and nasal regurgitation of liquids. He had no neuropsychiatric issues, and his family history was unremarkable. An obvious nasal twang, facial dysmorphism, and marfanoid body habitus were found on examination. The genetic tests revealed a pathogenic missense mutation in the MED12 gene on his X-chromosome.

CONCLUSION

LFS can present as acute-onset dysphagia and in the absence of any neuropsychiatric issues or positive family history of the syndrome.

A nondegenerate code of deleterious variants in Mendelian loci contributes to complex disease risk

Although countless highly penetrant variants have been associated with Mendelian disorders, the genetic etiologies underlying complex diseases remain largely unresolved. By mining the medical records of over 110 million patients, we examine the extent to which Mendelian variation contributes to complex disease risk. We detect thousands of associations between Mendelian and complex diseases, revealing a nondegenerate, phenotypic code that links each complex disorder to a unique collection of Mendelian loci. Using genome-wide association results, we demonstrate that common variants associated with complex diseases are enriched in the genes indicated by this "Mendelian code." Finally, we detect hundreds of comorbidity associations among Mendelian disorders, and we use probabilistic genetic modeling to demonstrate that Mendelian variants likely contribute nonadditively to the risk for a subset of complex diseases. Overall, this study illustrates a complementary approach for mapping complex disease loci and provides unique predictions concerning the etiologies of specific diseases.

Congenital and acquired disorders presenting as psychosis in children and young adults

A review of the published literature found 60 congenital and acquired disorders with symptoms that include psychosis in youth. The prevalence, workup, genetics, and associated neuropsychiatric features of each disorder are described. Eighteen disorders (30%) have distinct phenotypes (doorway diagnoses); 18 disorders (30%) are associated with intellectual disability; and 43 disorders (72%) have prominent neurologic signs. Thirty-one disorders (52%) can present without such distinct characteristics, and are thus more easily overlooked. A systematic and cost-effective differential diagnostic approach based on estimated prevalence and most prominent associated signs is recommended.

Characterization of a new X-linked mental retardation syndrome with microcephaly, cortical malformation, and thin habitus

X-linked mental retardation (XLMR) affects 1-2/1,000 males and accounts for approximately 10% of all mental retardation (MR). We have ascertained a syndromic form of XLMR segregating within a five-generation family with seven affected males. Prominent characteristics include mild to severe MR, cortical malformation, microcephaly, seizures, thin build with distinct facial features including a long and thin face, epicanthic folds, almond-shaped eyes, upslanting palpebral fissures and micrognathia and behavioral problems. Carrier females have normal physical appearance and intelligence. This combination of features is unreported and distinct from Lujan-Fryns syndrome, Snyder-Robinson syndrome, and zinc finger DHHC domain-containing 9-associated MR. We propose the name of this new syndrome to be CK syndrome.

Mutations in UPF3B, a member of the nonsense-mediated mRNA decay complex, cause syndromic and nonsyndromic mental retardation

Nonsense-mediated mRNA decay (NMD) is of universal biological significance. It has emerged as an important global RNA, DNA and translation regulatory pathway. By systematically sequencing 737 genes (annotated in the Vertebrate Genome Annotation database) on the human X chromosome in 250 families with X-linked mental retardation, we identified mutations in the UPF3 regulator of nonsense transcripts homolog B (yeast) (UPF3B) leading to protein truncations in three families: two with the Lujan-Fryns phenotype and one with the FG phenotype. We also identified a missense mutation in another family with nonsyndromic mental retardation. Three mutations lead to the introduction of a premature termination codon and subsequent NMD of mutant UPF3B mRNA. Protein blot analysis using lymphoblastoid cell lines from affected individuals showed an absence of the UPF3B protein in two families. The UPF3B protein is an important component of the NMD surveillance machinery. Our results directly implicate abnormalities of NMD in human disease and suggest at least partial redundancy of NMD pathways.

Lujan-Fryns syndrome (mental retardation, X-linked, marfanoid habitus)

The Lujan-Fryns syndrome or X-linked mental retardation with marfanoid habitus syndrome is a syndromal X-linked form of mental retardation, affecting predominantly males. The prevalence is not known for the general population. The syndrome is associated with mild to moderate mental retardation, distinct facial dysmorphism (long narrow face, maxillary hypoplasia, small mandible and prominent forehead), tall marfanoid stature and long slender extremities, and behavioural problems. The genetic defect is not known. The diagnosis is based on the presence of the clinical manifestations. Genetic counselling is according to X-linked recessive inheritance. Prenatal testing is not possible. There is no specific treatment for this condition. Patients need special education and psychological follow-up, and attention should be given to diagnose early psychiatric disorders.

Eating disorder in a patient with phenotypical features of Lujan-Fryns syndrome

We report a young patient with phenotypic, cognitive and behavioural features consistent with a diagnosis of Lujan-Fryns syndrome. He exhibited a severe eating disorder with food refusal and psychogenic loss of appetite, which led to a serious state of malnutrition. Behavioural difficulties including shyness, hyperactivity and emotional instability are present in almost 80% of the described patients with Lujan-Fryns syndrome but eating disorders have not been previously reported in this condition. A review of the behavioural problems in Lujan-Fryns syndrome and an approach to their management is discussed.

Psychopathology in the Lujan–Fryns syndrome: Report of two patients and review

We report on two new patients, the propositus and his maternal uncle, with Lujan-Fryns syndrome (LFS). One presented with mild mental retardation and both patient had Marfanoid habitus and similar craniofacial anomalies (they had a long and narrow face, small mandible, high-arched palate, and hypernasal voice) as previously reported by Lujan et al. in 1984 and Fryns and Buttiens in 1987. One of our patients had agenesis of the corpus callosum as described by Lujan. The second patient had an ascending aortic aneurysm like the patient described by Wittine et al. 1999. Both patients showed similar behavior and psychiatric disorders. In addition, we reviewed the literature for the presence of psychopathology in LFS. After studying the 32 published cases and the 2 described in this article, we found that more than 90% of the patients present with some type of psychopathology, the most frequent being an autistic-like disorder. In our opinion, the agenesis of the corpus callosum (complete or partial) and ascending aorta aneurysm are manifestations of LFS, and thus brain MRI and echocardiogram should be part of the routine evaluation. Additionally, the high prevalence of psychopathological alterations in these patients suggests the need for psychiatric evaluation at the time of diagnosis.

Specific Genetic Disorders and Autism: Clinical Contribution Towards their Identification

Autism is a heterogeneous disorder that can reveal a specific genetic disease. This paper describes several genetic diseases consistently associated with autism (fragile X, tuberous sclerosis, Angelman syndrome, duplication of 15q11-q13, Down syndrome, San Filippo syndrome, MECP2 related disorders, phenylketonuria, Smith-Magenis syndrome, 22q13 deletion, adenylosuccinate lyase deficiency, Cohen syndrome, and Smith-Lemli-Opitz syndrome) and proposes a consensual and economic diagnostic strategy to help practitioners to identify them. A rigorous initial clinical screening is presented to avoid unnecessary laboratory and imaging studies. Regarding psychiatric nosography, the concept of "syndromal autism"--autism associated with other clinical signs should be promoted because it may help to distinguish patients who warrant a multidisciplinary approach and further investigation.

Terminal deletion of chromosome 5p in a patient with phenotypical features of Lujan-Fryns syndrome

We report a young man with phenotypical features suggestive of Lujan-Fryns syndrome and behaviour of an autistic spectrum disorder, who has a subtle terminal deletion of the short arm of chromosome 5. Individuals reported previously with a similar chromosomal abnormality have had developmental delay and a 'breathy, raspy' voice. It may be appropriate to consider screening patients with a phenotype suggestive of Lujan-Fryns syndrome by fluorescence in situ hybridisation (FISH) using a probe for the subtelomeric region of the short arm of chromosome 5.

Preserved neurobehavioral abilities in Lujan-Fryns syndrome

We present a patient with all the physical characteristics of Lujan-Fryns syndrome, including Marfanoid habitus, mild general hypotonia, hypernasal voice, normal testicular size, and distinct craniofacial anomalies. Despite the presence of impaired mental abilities in many areas, this young man showed intact concrete problem-solving skills under structured, interactive conditions. In addition, he did not demonstrate any of the psychiatric features that have often been reported with this syndrome. We conclude that Lujan-Fryns syndrome can be associated with partial preservation of neurobehavioral abilities.

The clinical phenotype in institutionalised adult males with X-linked mental retardation (XLMR)

In an institutionalised population of 471 mentally retarded adult residents (436 males and 35 females), 22 males (i.e. 5 % of the male population) had XLMR, accounting for 36.1 % of the residents diagnosed with a monogenic disorder (n = 61). Fragile X syndrome (FRAXA) was diagnosed in 16 residents, X-linked mental retardation with marfanoid habitus (Lujan-Fryns syndrome) in 2, and non-specific X-linked mental retardation (MRX) in 4 males. The 4 MRX-patients included 3 male sibs of a family, carrying a mutation in the IL-1 receptor accessory protein-like gene, and one male patient member of the MRX-44 family (linkage with LOD-score of 2.90). In the group of 215 males with idiopathic mental retardation (MR), family histories and pedigree data were compatible with XLMR in 35 males (35/215 = 16.3 %) from 32 families. Of these 35 males, 5.7 % were microcephalic with dysmorphic features and 5.7 % macrocephalic; micro-orchidism and macro-orchidism were each found in 11.4 %. One macrocephalic male had also macro-orchidism and dysmorphic features. In this study, the diagnosis of XLMR could thus be proposed in 57 males i.e. 13.1 % of the total male population. The clinical phenotype, behavioural problems and follow-up data in these different subgroups of XLMR are presented.

Aortic root dilation in apparent Lujan-Fryns syndrome

We present a patient and his maternal uncle who have a subaortic ventricular septal defect and aortic root dilation. They both have physical anomalies, characteristic behaviors, and cognitive disabilities that are consistent with the diagnosis of Lujan-Fryns syndrome (LFS). Although there have been 4 cases reported in the literature with heart findings, ventricular septal defect and aortic root dilation have not been previously reported in LFS. Differentiation between LFS and Marfan syndrome (MS) is discussed. The pathophysiology of LFS as a connective tissue disorder is also considered.