X-linked Aarskog syndrome: report on a novel FGD1 gene mutation. Executive dysfunction as part of the behavioural phenotype.

Aarskog-Scott syndrome [OMIM 100050] is a predominantly X-linked disorder that is phenotypically characterized by short stature, craniofacial dysmorphisms, brachydactyly and urogenital abnormalities. The level of intelligence shows a great variability and no specific behavioural phenotype has been described so far. In about 20 percent ofAarskog families, a mutation in the FGD1 gene located in Xp11.21 can be identified. In the present study, four affected males from the fourth generation of a large Dutch family (published in 1983 by Van de Vooren et al. (41)) are described. A novel FGD1 missense mutation (R402W) at position 1204 (1204C>T) was demonstrated. In the patients, the level of intelligence varied between normal and severely disabled. Their behavioural profile showed, among others, elements of attention deficit hyperactivity disorder, primarily reflected by impaired executive attentional processes that may be sensitive to systematic training.

Undetected anomalies in foetuses with a prenatal diagnosis of isolated cleft.

The aim of this study was to determine the rate of undetected additional anomalies following a prenatal diagnosis of isolated oral cleft. Data of all infants with a prenatal diagnosis of isolated oral cleft born between 2000 and 2015 were studied retrospectively. Additional anomalies detected after birth were categorized as minor or major and included structural and chromosomal anomalies. Isolated clefts of the lip (CL), lip and alveolus (CLA) and lip, alveolus, and palate (CLAP) were diagnosed prenatally in 176 live-born infants. The type of cleft was more extensive after birth in 34/176 (19.3%) and less extensive in 16/176 (9.1%) newborns. Additional anomalies were diagnosed in 24 infants (13.6%), of which 12 (6.8%) were categorized as major. The latter included two submicroscopic chromosome anomalies and two gene mutations. Postnatal additional anomalies occurred more frequently in CLA and CLAP than in CL, and more in bilateral than in unilateral clefts. Major anomalies are still found in infants with a prenatal diagnosis of an isolated oral cleft. The prevalence of additional anomalies seems to be related to the type and bilaterality of the cleft, and this should be considered during prenatal counselling.

Deletion of 1 amino acid in Indian hedgehog leads to brachydactylyA1.

Brachydactyly type A1 is a limb malformation characterized by a uniform shortening of the middle phalanges in all digits. Mutations in the Indian hedgehog (IHH) gene were shown to be the cause of this autosomal dominant disorder. The IHH protein is known to be an important signaling molecule involved in chondrocyte formation. So far, only missense mutations in IHH have been reported to cause BrachydactylyA1. We report here on the first deletion in IHH, p.delE95, causing mild BrachydactylyA1 in a small Dutch family. This brings the total number of different mutations found to cause BDA1 to 7.

[Genetics of craniofacial development]. / Genetica van de ontwikkeling van schedel en aangezicht.

Congenital craniofacial malformations vary widely in both expression and gravity. To understand congenital craniofacial malformations, knowledge of embryonic development is of essential importance. Craniosynostosis has its origin in the failure of suture development between 2 bone centres or in early closure of the suture by bone centre tissue fusion. Hereditary craniosynostosis phenotypes predominantly arise by autosomal dominant inheritance. So far, the majority of mutations have been found in fibroblast growth-factor receptor genes (FGFR-genes). Different phenotypes are not primarily created by disparities of the receptors, but particularly by tissue-specific expressions.

NGS panel analysis in 24 ectopia lentis patients; a clinically relevant test with a high diagnostic yield.

BACKGROUND: Several genetic causes of ectopia lentis (EL), with or without systemic features, are known. The differentiation between syndromic and isolated EL is crucial for further treatment, surveillance and counseling of patients and their relatives. Next generation sequencing (NGS) is a powerful tool enabling the simultaneous, highly-sensitive analysis of multiple target genes. OBJECTIVE: The aim of this study was to evaluate the diagnostic yield of our NGS panel in EL patients. Furthermore, we provide an overview of currently described mutations in ADAMTSL4, the main gene involved in isolated EL. METHODS: A NGS gene panel was analysed in 24 patients with EL. RESULTS: A genetic diagnosis was confirmed in 16 patients (67%). Of these, four (25%) had a heterozygous FBN1 mutation, 12 (75%) were homozygous or compound heterozygous for ADAMTSL4 mutations. The known European ADAMTSL4 founder mutation c.767_786del was most frequently detected. CONCLUSION: The diagnostic yield of our NGS panel was high. Causative mutations were exclusively identified in ADAMTSL4 and FBN1. With this approach the risk of misdiagnosis or delayed diagnosis can be reduced. The value and clinical implications of establishing a genetic diagnosis in patients with EL is corroborated by the description of two patients with an unexpected underlying genetic condition.

[From gene to disease; craniosynostosis syndromes due to FGFR2-mutation]. / Van gen naar ziekte; craniosynostosesyndromen door FGFR2-mutaties.

One of the genes involved in craniosynostosis syndromes is the fibroblast growth factor receptor 2 (FGFR2) gene, a tyrosine kinase receptor gene. Upon ligand binding the FGFR2 receptors dimerise, and this is followed by activation of the intracellular tyrosine kinase domains. This initiates a cascade of signals that influence cell division and differentiation. FGFR2 mutations have been found in the Apert, Crouzon and Pfeiffer craniosynostosis syndromes. Most mutations are gain of function mutations, inducing ligand-independent receptor activation or altered ligand binding. With the exception of Apert syndrome, there is no clear genotype-phenotype correlation. Many different mutations have been found in Pfeiffer and Crouzon syndrome, but all of the mutations occur in the same extracellular region of the receptor. Identical mutations have been found in Pfeiffer and Crouzon syndrome. So within one family, both Crouzon and Pfeiffer syndrome may occur. Mutations in other FGFR-genes have also been found in craniosynostosis syndromes.

Phenotypes of craniofrontonasal syndrome in patients with a pathogenic mutation in EFNB1.

Craniofrontonasal syndrome (CFNS) is an X-linked developmental malformation, caused by mutations in the EFNB1 gene, which have only been described since 2004. A genotype-phenotype correlation seems not to be present. As it is of major importance to adequately counsel patients with EFNB1 mutations and their parents, and to improve diagnosis of new patients, more information about the phenotypic features is needed. This study included 23 patients (2 male, 21 female) with confirmed EFNB1 mutations. All patients underwent a thorough physical examination and photographs were taken. If available, radiological images were also consulted. Hypertelorism, longitudinal ridging and/or splitting of nails, a (mild) webbed neck and a clinodactyly of one or more toes were the only consistent features observed in all patients. Frequently observed phenotypic features were bifid tip of the nose (91%), columellar indentation (91%) and low implantation of breasts (90%). In comparison with anthropometric data of facial proportions, patients with CFNS had a significantly different face in multiple respects. An overview of all phenotypic features is shown. Patients with EFNB1 mutations have a clear phenotype. This study will facilitate genetic counseling of parents and patients, and contribute to the diagnostic and screening process of patients with suspected CFNS.

Long-term functional outcome in 167 patients with syndromic craniosynostosis; defining a syndrome-specific risk profile.

OBJECTIVE: Little is known about the long-term prevalence of elevated intracranial pressure (ICP), obstructive sleep apnoea (OSA), level of education, language and motor skills, impaired sight and hearing in craniosynostosis syndromes. The objective of this study was to define the prevalence per syndrome of elevated ICP, OSA, impaired sight and impaired hearing. METHODS: A retrospective study was undertaken on 167 consecutive patients diagnosed with Apert, Crouzon, Pfeiffer, Muenke or Saethre-Chotzen syndrome, aged 1-25 years and treated between 1983 and 2008. The mean age at time of referral and review was 1 years and 2 months and 10 years and 3 months, respectively. RESULTS: Patients with Apert and Crouzon/Pfeiffer syndromes had the highest prevalence of elevated ICP (33% and 53%, respectively) and OSA (31% and 27%, respectively), while Saethre-Chotzen syndrome was also associated with a fair risk for elevated ICP (21%). The prevalence of impaired sight (61%) and hearing (56%) was high in all syndromes. CONCLUSION: Based on these data, a syndrome-specific risk profile with suggestions for screening and treatment is presented.

[Prenatally detected orofacial cleft]. / Prenataal vastgestelde orofaciale schisis.

An increasing number of pregnancies are presumed being terminated following prenatal detection of orofacial cleft during structural ultrasound.After examining the data and literature on this topic it is concluded that the reported cases are merely incidents. For the interpretation of prenatal detection rates a distinction should be made between isolated orofacial cleft and the frequently occurring associated form of orofacial cleft which is usually characterized by other, often major structural or chromosome anomalies. The ultrasound detection rate of the isolated form is low and varies in the literature between 18 and 56%. Together with all Dutch centres of prenatal medicine a care plan was adopted for the management of prenatally detected orofacial cleft including diagnosis (detailed ultrasound examination and karyotyping), medical support (genetic consultations, plastic surgery and psychosocial counselling) and treatment (obstetric and neonatal management). In the presence of associated major congenital anomalies termination of pregnancy may be considered before the 24th week of pregnancy.

Deletion of the TWIST gene in a large five-generation family.

In this article, we describe a large five-generation family with characteristics of the Saethre-Chotzen syndrome as well as of the blepharophimosis ptosis epicanthus inversus syndrome. Segregating with their phenotype is a deletion of the chromosome 7p21 TWIST gene locus. The TWIST gene indeed is involved in Saethre-Chotzen syndrome, a craniosynostosis syndrome further characterized by specific facial and limb abnormalities. However, only two members of our family exhibited craniosynostosis. This report demonstrates that the genetics of craniofacial anomalies are less straightforward than they sometimes appear to be. Not only craniosynostosis, but also subtle facial deformities could be indicative of an abnormality of the TWIST gene. In conclusion, the clinical spectrum of genetic abnormalities of the TWIST gene is highly variable. We therefore recommend that genetic analysis of the TWIST gene locus, including fluorescence in situ hybridization, should be considered in familial cases of facial and eyelid abnormalities without the presence of craniosynostosis.

Early diagnosis of Wolf-Hirschhorn syndrome triggered by a life-threatening event: congenital diaphragmatic hernia.

Wolf-Hirschhorn syndrome (WHS, OMIM 194190) is a chromosomal disorder characterized by retarded mental and physical growth, microcephaly, Greek helmet appearance of the facies, seizures/epilepsy. Closure defects of lip or palate, and cardiac septum defects occur in 30-50% of cases. Its cause is a deletion in the short arm of chromosome 4. We present a male patient, born after 37 weeks gestation, as the fourth pregnancy of non-consanguineous healthy parents, with unilateral cleft lip and palate, hypertelorism, a right-sided ear tag, and mild epispadias. At age 10 weeks he developed acute respiratory distress and acute bowel obstruction requiring emergency laparotomy. This revealed a left-sided posterolateral diaphragmatic defect, type Bochdalek, with incarceration of the small intestines necessitating major bowel resection. Clinical genetic investigation suggested a chromosome anomaly, but regular karyotyping was normal. However, FISH analysis showed a microdeletion in the short arm of chromosome 4 (4p-), consistent with WHS. A combination of this syndrome with congenital diaphragmatic hernia (CDH) has been rarely described. CDH can present either as an isolated defect at birth, or with multiple congenital abnormalities, or as part of a defined syndrome or chromosomal disorder. Therefore CDH, although not common in WHS, can lead to its diagnosis relatively early in life. We strongly recommend a clinical genetic evaluation of each CDH patient with facial anomalies taking into consideration 4p- deletion syndrome.