Robin sequence without cleft palate: Genetic diagnoses and management implications.

Robin sequence (RS), the triad of micrognathia, glossoptosis, and airway obstruction, is a major cause of respiratory distress and feeding difficulties in neonates. Robin sequence can be associated with other medical or developmental comorbidities in ~50% of cases ("syndromic" RS). As well, RS is variably associated with cleft palate (CP). Previous studies have not investigated differences in clinical characteristics of children with RS based on presence or absence of CP. We retrospectively reviewed 175 children with RS and compared genetic diagnoses, medical and developmental comorbidities, severity of airway obstruction, and feeding outcomes between those with and without CP. Strikingly, 45 of 45 (100%) children with RS without CP were classified as syndromic due to presence of comorbidities unrelated to RS, while 83 of 130 (64%) children with RS with CP were classified as syndromic. Among 128 children with syndromic RS, there were no differences in severity of airway obstruction, surgical intervention rate or type, or feeding outcome at 12 months based on CP status. Our findings support the conclusion that the pathogenesis of RS without CP is distinct from RS with CP and more likely to cause additional medical or developmental problems. Alternatively, children with RS without CP and without additional anomalies present may be under recognized.

Mandibulofacial dysostosis with microcephaly: An expansion of the phenotype via parental survey.

Mandibulofacial dysostosis with microcephaly (MFDM) is due to haploinsufficiency of spliceosomal GTPase EFTUD2. Features include microcephaly, craniofacial dysmorphology, developmental disability, and other anomalies. We surveyed parents of individuals with MFDM to expand knowledge about health, development, and parental concerns. Participants included attendees of the inaugural MFDM family conference in June 2019 and members of the MFDM online group. To explore MFDM variable expressivity, we offered targeted Sanger sequencing for untested parents. Forty-seven parents participated in the survey. 59% of individuals with MFDM were male, with mean age 6.4 years (range 8 months to 49 years). Similar to the literature (n = 123), common features include microcephaly, cleft palate, choanal stenosis, tracheoesophageal fistula, heart problems, and seizures. New information includes airway intervention details, age-based developmental outcomes, rate of vision refractive errors, and lower incidences of prematurity and IUGR. Family concerns focused on development, communication, and increased support. Targeted Sanger sequencing for families of seven individuals demonstrated de novo variants, for a total of 91.9% de novo EFTUD2 variants (n = 34/37). This study reports the largest single cohort of individuals with MFDM, expands phenotypic spectrum and inheritance patterns, improves understanding of developmental outcomes and care needs, and identifies development as the biggest concern for parents.

Acrofacial Dysostosis, Cincinnati Type, a Mandibulofacial Dysostosis Syndrome with Limb Anomalies, Is Caused by POLR1A Dysfunction.

We report three individuals with a cranioskeletal malformation syndrome that we define as acrofacial dysostosis, Cincinnati type. Each individual has a heterozygous mutation in POLR1A, which encodes a core component of RNA polymerase 1. All three individuals exhibit varying degrees of mandibulofacial dysostosis, and two additionally have limb anomalies. Consistent with this observation, we discovered that polr1a mutant zebrafish exhibited cranioskeletal anomalies mimicking the human phenotype. polr1a loss of function led to perturbed ribosome biogenesis and p53-dependent cell death, resulting in a deficiency of neural-crest-derived skeletal precursor cells and consequently craniofacial anomalies. Our findings expand the genotypic and phenotypic heterogeneity of congenital acrofacial disorders caused by disruption of ribosome biogenesis.

A new frontonasal dysplasia syndrome associated with deletion of the SIX2 gene.

The frontonasal dysplasias are a group of craniofacial phenotypes characterized by hypertelorism, nasal clefting, frontal bossing, and abnormal hairline. These conditions are caused by recessive mutations in members of the aristaless gene family, resulting in abnormal cranial neural crest migration and differentiation. We report a family with a dominantly inherited craniofacial phenotype comprised of frontal bossing with high hairline, ptosis, hypertelorism, broad nasal tip, large anterior fontanelle, cranial base anomalies, and sagittal synostosis. Chromosomal microarray identified a heterozygous 108.3 kilobase deletion of chromosome 2p21 segregating with phenotype and limited to the sine oculis homeobox gene SIX2 and surrounding noncoding DNA. Similar to the human SIX2 deletion phenotype, one mouse model of frontonasal dysplasia, brachyrrhine, exhibits dominant inheritance and impaired cranial base chondrogenesis associated with reduced Six2 expression. We report the first human autosomal dominant frontonasal dysplasia syndrome associated with SIX2 deletion and with phenotypic similarities to murine models of Six2 Loss-of-function.

Neonates with tongue-based airway obstruction: a systematic review.

OBJECTIVE: In this systematic review, the authors summarize the current evidence in the literature regarding diagnosis, treatment, and long-term outcomes in neonates with tongue-based airway obstruction (TBAO) and assess the level of evidence of included studies. DATA SOURCES: The terms Pierre Robin syndrome/sequence, micrognathia, retrognathia, and cleft palate were combined with airway obstruction, treatment, tongue-lip plication, and osteogenesis distraction to perform an Ovid literature search, yielding 341 references. The authors excluded references containing patients with isolated choanal/nasal obstruction, patients older than 12 months, and expert opinion papers, yielding 126 articles. REVIEW METHODS: The authors searched 3 electronic databases and reference lists of existing reviews from 1980 to October 2010 for articles pertaining to the diagnosis, treatment, and outcomes of TBAO. Reviewers assigned a level of evidence score based on Oxford's Centre for Evidence Based Medicine scoring system and recorded relevant information. RESULTS: Most studies were case studies and single-center findings. The lack of standardization of diagnostic and treatment protocols and the heterogeneity of cohorts both within and between studies precluded a meta-analysis. There was little evidence beyond expert opinion and single-center evaluation regarding diagnosis, treatment, and long-term outcomes of neonates with TBAO. CONCLUSIONS: The variability in the phenotype of the cohorts studied and the absence of standardized indications for intervention preclude deriving any definitive conclusions regarding diagnostic tools to evaluate this patient population, treatment choices, or long-term outcomes. A coordinated multicenter study with a standardized diagnostic and treatment algorithm is recommended to develop evidence for the diagnosis and treatment of neonates with TBAO.

Evaluation of growth in patients with isolated cleft lip and/or cleft palate.

OBJECTIVE: The purpose of the study was to evaluate the growth of patients with isolated cleft lip (CL), with or without cleft palate (CP), or CP during the first few years of life. METHODS: A retrospective analysis of data from birth to 5 years for 307 patients with isolated CL/CP or CP alone who were seen in a large craniofacial center between 1980 and 2007 was performed. We analyzed growth patterns and feeding interventions. Anthropometric values were plotted onto 2000 Centers for Disease Control and Prevention charts. Longitudinal analyses were performed to estimate age-related changes and to test whether feeding interventions or early education influenced age-related changes. RESULTS: Including progressive weight, length, and head circumference values, a total of 1944 data points were available. The most frequent diagnosis was unilateral CL with CP (165 [53.7%] of 307 cases). No patients experienced significant failure to thrive during the study period, although predicted weight and length percentiles for age had initial decreases during the first year of life, with nadirs at 5.2 and 15 months, respectively. These decreases were followed by recovery that started at approximately 12 months for weight and at 20 months for length (P < .0001). Patients who had feeding interventions had a significantly (P = .047) increased gain rate over time for weight for length, compared with those who did not. CONCLUSIONS: In this population, there were weight and length decreases during the first year of life, which were not clinically significant and were followed by statistically significant recovery. Recovery seemed to be related to successful education and feeding interventions. Head circumference and weight for length started at lower percentiles but showed consistent gain over time.