Elements of morphology: Standard terminology for the ear-Additional features

Molecular Bases of Human Malformation Syndromes Involving the SHH Pathway: GLIA/R Balance and Cardinal Phenotypes

Human hereditary malformation syndromes are caused by mutations in the genes of the signal transduction molecules involved in fetal development. Among them, the Sonic hedgehog (SHH) signaling pathway is the most important, and many syndromes result from its disruption. In this review, we summarize the molecular mechanisms and role in embryonic morphogenesis of the SHH pathway, then classify the phenotype of each malformation syndrome associated with mutations of major molecules in the pathway. The output of the SHH pathway is shown as GLI activity, which is generated by SHH in a concentration-dependent manner, i.e., the sum of activating form of GLI (GLIA) and repressive form of GLI (GLIR). Which gene is mutated and whether the mutation is loss-of-function or gain-of-function determine in which concentration range of SHH the imbalance occurs. In human malformation syndromes, too much or too little GLI activity produces symmetric phenotypes affecting brain size, craniofacial (midface) dysmorphism, and orientation of polydactyly with respect to the axis of the limb. The symptoms of each syndrome can be explained by the GLIA/R balance model.

Recurrent Mutations in the Basic Domain of TWIST2 Cause Ablepharon Macrostomia and Barber-Say Syndromes

Ablepharon macrostomia syndrome (AMS) and Barber-Say syndrome (BSS) are rare congenital ectodermal dysplasias characterized by similar clinical features. To establish the genetic basis of AMS and BSS, we performed extensive clinical phenotyping, whole exome and candidate gene sequencing, and functional validations. We identified a recurrent de novo mutation in TWIST2 in seven independent AMS-affected families, as well as another recurrent de novo mutation affecting the same amino acid in ten independent BSS-affected families. Moreover, a genotype-phenotype correlation was observed, because the two syndromes differed based solely upon the nature of the substituting amino acid: a lysine at TWIST2 residue 75 resulted in AMS, whereas a glutamine or alanine yielded BSS. TWIST2 encodes a basic helix-loop-helix transcription factor that regulates the development of mesenchymal tissues. All identified mutations fell in the basic domain of TWIST2 and altered the DNA-binding pattern of Flag-TWIST2 in HeLa cells. Comparison of wild-type and mutant TWIST2 expressed in zebrafish identified abnormal developmental phenotypes and widespread transcriptome changes. Our results suggest that autosomal-dominant TWIST2 mutations cause AMS or BSS by inducing protean effects on the transcription factor's DNA binding.

Under-recognition of 22q11.2 deletion in adult Chinese patients with conotruncal anomalies: implications in transitional care

22q11.2 deletion syndrome (22q11.2DS) is a multi-systemic disorder with high phenotypic variability. Under-diagnosis in adults is common and recognition of facial dysmorphic features can be affected by age and ethnicity. This study aims to determine the prevalence of undiagnosed 22q11.2DS in adult Chinese patients with conotruncal anomalies and to delineate their facial dysmorphisms and extra-cardiac manifestations. We recruited consecutively 156 patients with conotruncal anomalies in an adult congenital heart disease (CHD) clinic in Hong Kong and screened for 22q11.2DS using fluorescence-PCR and fluorescence in-situ hybridization. Assessment for dysmorphic features was performed by a cardiologist at initial screening and then by a clinical geneticist upon result disclosure. Clinical photographs were taken and childhood photographs collected. Eighteen patients (11.5%) were diagnosed with 22q11.2DS, translating into 1 previously unrecognized diagnosis of 22q11.2DS in every 10 adult patients with conotruncal anomalies. While dysmorphic features were detected by our clinical geneticist in all patients, only two-thirds were considered dysmorphic by our cardiologist upon first assessment. Evolution of facial dysmorphic features was noted with age. Extra-cardiac manifestations included velopharyngeal incompetence or cleft palate (44%), hypocalcemia (39%), neurodevelopmental anomalies (33%), thrombocytopenia (28%), psychiatric disorders (17%), epilepsy (17%) and hearing loss (17%). We conclude that under-diagnosis of 22q11.2DS in Chinese adults with conotruncal defects is common and facial dysmorphic features may not be reliably recognized in the setting of adult CHD clinic, referral for genetic evaluation and molecular testing for 22q11.2DS should be offered to patients with conotruncal defects.

Array-based comparative genomic hybridization in 190 Korean patients with developmental delay and/or intellectual disability: a single tertiary care university center study

PURPOSE

This study analyzed and evaluated the demographic, clinical, and cytogenetic data [G-banded karyotyping and array-based comparative genomic hybridization (array CGH)] of patients with unexplained developmental delay or intellectual disability at a single Korean institution.

MATERIALS AND METHODS

We collected clinical and cytogenetic data based on retrospective charts at Ajou University Medical Center, Suwon, Korea from April 2008 to March 2012.

RESULTS

A total of 190 patients were identified. Mean age was 5.1±1.87 years. Array CGH yielded abnormal results in 26 of 190 patients (13.7%). Copy number losses were about two-fold more frequent than gains. A total of 61.5% of all patients had copy number losses. The most common deletion disorders included 22q11.2 deletion syndrome, 15q11.2q12 deletion and 18q deletion syndrome. Copy number gains were identified in 34.6% of patients, and common diseases among these included Potocki-Lupski syndrome, 15q11-13 duplication syndrome and duplication 22q. Abnormal karyotype with normal array CGH results was exhibited in 2.6% of patients; theses included balanced translocation (n=2), inversion (n=2) and low-level mosaicism (n=1). Facial abnormalities (p<0.001) and failure to thrive were (p<0.001) also more frequent in the group of patients with abnormal CGH findings.

CONCLUSION

Array CGH is a useful diagnostic tool in clinical settings in patients with developmental delay or intellectual disability combined with facial abnormalities or failure to thrive.

Morphologic abnormalities in 2-year-old children born after in vitro fertilization/intracytoplasmic sperm injection with preimplantation genetic screening: follow-up of a randomized controlled trial

OBJECTIVE

To evaluate the effect of preimplantation genetic screening (PGS) on morphologic outcome in children.

DESIGN

Follow-up of a randomized controlled trial (RCT).

SETTING

University hospital.

PATIENT(S)

Two-year-old children born to mothers who participated in an RCT on the efficacy of PGS: 50 children born after in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) with PGS (intervention group; PGS+) and 72 children born after IVF/ICSI only (control group; PGS-). Sixty-six age-matched children conceived without any form of assisted reproduction were recruited separately in a local public health service center (reference group).

INTERVENTION(S)

PGS.

MAIN OUTCOME MEASURE(S)

Body surface examination and anthropometry. The evaluation of morphologic abnormalities allowed assessment of children's phenotype in detail. Morphologic abnormalities were classified as major abnormalities (abnormal development in organogenesis, deformations, disruptions, or dysplasia) and minor anomalies (deviations in phenogenesis).

RESULT(S)

The percentage of children with ≥ 1 major abnormality was 28% in the PGS+ and 35% in the PGS- group [difference -7%, 95% CI -23% to 10%]. The percentage of children with ≥ 1 minor anomaly was 64% in the PGS+ and 67% in the PGS- group [difference -3%, 95% CI -15% to 20%]. In the reference group 30% of the children had ≥ 1 major abnormality [95% CI 20% to 43%] and 74% had ≥ 1 minor anomaly [95% CI 62% to 84%].

CONCLUSION(S)

No statistically significant differences were found in minor anomalies between children conceived after IVF/ICSI with or without PGS. There is < 2.5% chance of ≥ 10% more major abnormalities in children born after PGS.