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

Investigations of an individual with a Marfanoid habitus, mild intellectual disability, and severe social anxiety identifies PCDHGA5 as a candidate neurodevelopmental disorder gene

Marfanoid habitus and intellectual disability (MHID) co-occur in multiple neurodevelopmental disorders (NDD). Among those, Lujan-Fryns, an X-linked genetic disorder associated with variants in MED12 was the first such syndrome identified. Accurate molecular diagnosis for these MHID syndromes remains a challenge due to significant clinical and genetic heterogeneity. We present a case report of a 20-year-old male patient with MHID and severe social anxiety. A comprehensive clinical evaluation, including morphotype assessment, cognitive, and psychometric and genetic testing, was conducted to provide a detailed understanding of the patient's complex clinical presentation. Psychometric assessments revealed severe social anxiety and various cognitive and emotional challenges. Despite some autism-like symptoms, the patient's clinical presentation was more aligned with mild intellectual disability. Exome sequencing was inconclusive but identified a heterozygous de novo missense variant in the PCDHGA5 gene. This gene is not known in human pathology yet, but we also report a second patient with a syndromic neurodevelopmental disorder and a rare de novo variant which leads us to propose this as a candidate gene. Our findings emphasize the importance of multidisciplinary approach in the diagnosis and management of MHID. This case report underscores the need for objective clinical evaluations and standardized tools to better understand the complex clinical profiles of patients with NDDs. The identification of novel PCDHGA5 gene variants adds this gene's candidacy to the genetic landscape of MHID-NDD, warranting further investigation to determine its potential contribution.

Systematic molecular and cytogenetic screening of 100 patients with marfanoid syndromes and intellectual disability

The association of marfanoid habitus (MH) and intellectual disability (ID) has been reported in the literature, with overlapping presentations and genetic heterogeneity. A hundred patients (71 males and 29 females) with a MH and ID were recruited. Custom-designed 244K array-CGH (Agilent®; Agilent Technologies Inc., Santa Clara, CA) and MED12, ZDHHC9, UPF3B, FBN1, TGFBR1 and TGFBR2 sequencing analyses were performed. Eighty patients could be classified as isolated MH and ID: 12 chromosomal imbalances, 1 FBN1 mutation and 1 possibly pathogenic MED12 mutation were found (17%). Twenty patients could be classified as ID with other extra-skeletal features of the Marfan syndrome (MFS) spectrum: 4 pathogenic FBN1 mutations and 4 chromosomal imbalances were found (2 patients with both FBN1 mutation and chromosomal rearrangement) (29%). These results suggest either that there are more loci with genes yet to be discovered or that MH can also be a relatively non-specific feature of patients with ID. The search for aortic complications is mandatory even if MH is associated with ID since FBN1 mutations or rearrangements were found in some patients. The excess of males is in favour of the involvement of other X-linked genes. Although it was impossible to make a diagnosis in 80% of patients, these results will improve genetic counselling in families.

Hereditary disorders of connective tissue: a guide to the emerging differential diagnosis

PURPOSE

To create a practical desk reference for clinicians focused on the differential diagnosis of individuals presenting with features that suggest an inherited disorder of connective tissue.

METHODS

We searched the medical literature for distinct clinical entities that shared clinical features with Marfan syndrome and other classical inherited disorders of connective tissue.

RESULTS

Thirty-six distinct heritable disorders of connective tissue were identified that have overlapping features. These disorders were organized into two matrices according to clinical characteristics and according to causative genes.

CONCLUSIONS

A broad differential diagnosis is emerging for individuals presenting with features suggestive of altered connective tissue. Recent advances in molecular genetics have aided in the delineation of these disorders.

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.

Cri du Chat syndrome

The Cri du Chat syndrome (CdCS) is a genetic disease resulting from a deletion of variable size occurring on the short arm of chromosome 5 (5p-). The incidence ranges from 1:15,000 to 1:50,000 live-born infants. The main clinical features are a high-pitched monochromatic cry, microcephaly, broad nasal bridge, epicanthal folds, micrognathia, abnormal dermatoglyphics, and severe psychomotor and mental retardation. Malformations, although not very frequent, may be present: cardiac, neurological and renal abnormalities, preauricular tags, syndactyly, hypospadias, and cryptorchidism. Molecular cytogenetic analysis has allowed a cytogenetic and phenotypic map of 5p to be defined, even if results from the studies reported up to now are not completely in agreement. Genotype-phenotype correlation studies showed a clinical and cytogenetic variability. The identification of phenotypic subsets associated with a specific size and type of deletion is of diagnostic and prognostic relevance. Specific growth and psychomotor development charts have been established. Two genes, Semaphorin F (SEMAF) and delta-catenin (CTNND2), which have been mapped to the "critical regions", are potentially involved in cerebral development and their deletion may be associated with mental retardation in CdCS patients. Deletion of the telomerase reverse transcriptase (hTERT) gene, localised to 5p15.33, could contribute to the phenotypic changes in CdCS. The critical regions were recently refined by using array comparative genomic hybridisation. The cat-like cry critical region was further narrowed using quantitative polymerase chain reaction (PCR) and three candidate genes were characterised in this region. The diagnosis is based on typical clinical manifestations. Karyotype analysis and, in doubtful cases, FISH analysis will confirm the diagnosis. There is no specific therapy for CdCS but early rehabilitative and educational interventions improve the prognosis and considerable progress has been made in the social adjustment of CdCS patients.

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.

8.5 Mb deletion at distal 5p in a male ascertained for azoospermia

We report on a 5p- azoospermic male not showing the clinical features diagnostic for the cri-du-chat syndrome but for a breathy, raspy voice. The 5p deletion breakpoint, determined by fluorescent in situ hybridization (FISH) analysis with BAC clones, maps 8.5 Mb far from the short arm telomere in 5p15.31. Genotype/phenotype correlations in this subject, including his neuropsychological assessment, led us to define that the gene for the cat-like cry and one gene responsible for mild mental retardation with speech delay map both in the distal 8.5 Mb of chromosome 5 short arm.

A variant Cri du Chat phenotype and autism spectrum disorder in a subject with de novo cryptic microdeletions involving 5p15.2 and 3p24.3-25 detected using whole genomic array CGH

Cri du Chat syndrome (CdCs) is a well-defined clinical entity, with an incidence of 1/15,000 to 1/50,000. The critical region for CdCs has been mapped to 5p15, with the hallmark cat-like cry sublocalized to 5p15.3 and the remaining clinical features to 5p15.2. We report findings in a subject with a de novo t(5;7)(p15.2;p12.2) and an inv(3)(p24q24), who was found to have a cryptic microdeletion in the critical region for CdCs detected using a 1-Mb genomic microarray. In addition to 5p deletion, the proband had a de novo single clone loss at the 3p breakpoint of inv(3)(p24q24) and a familial single clone deletion at 18q12. Deletions were confirmed using microsatellite analysis and fluorescence in situ hybridization. The 5p deletion encompasses approximately 3 Mb, mapping to the border between bands 5p15.2 and 5p15.31. The single clone deletion on chromosome 3 maps to 3p24.3-3p25, for which there is no known phenotype. The clinical features of our proband differ from the characteristic CdC phenotype, which may reflect the combined effect of the two de novo microdeletions and/or may further refine the critical region for CdCs. Typical features of CdCs that are present in the proband include moderate intellectual disability, speech, and motor delay as well as dysmorphic features (e.g. broad and high nasal root, hypertelorism, and coarse facies). Expected CdCs features that are not present are growth delay, microcephaly, round facies, micrognathia, epicanthal folds, and the signature high-pitched cry. Behavioral traits in this subject included autism spectrum disorder, attention-deficit hyperactivity disorder, and unmanageable behavior including aggression, tantrums, irritability, and self-destructive behavior. Several of these behaviors have been previously reported in patients with 5p deletion syndrome. Although most agree on the cat-cry critical region (5p15.3), there is discrepancy in the precise location and size of the region associated with the more severe manifestations of CdCs. The clinical description of this proband and the characterization of his 5p deletion may help to further refine the phenotype-genotype associations in CdCs and autism spectrum disorder.