Guillermo Lay-Son

Case fatality rate and associated factors in patients with 22q11 microdeletion syndrome: a retrospective cohort study

Objective Chromosome 22q11.2 deletion is the most commonly occurring known microdeletion syndrome. Deaths related to the syndrome have been reported, but the magnitude of death has not been quantified. This study evaluated the deletions impact on survival and its clinical manifestations in a large cohort of Chilean patients. Design Demographic and clinical data of individuals with 22q11 deletions diagnosed between 1998 and 2013 were collected from medical records and death certificates. Case fatality rate was calculated and compared with national vital statistics. OR with 95% CI analysis was used to assess the association between clinical manifestations and death. Setting Genetic services in tertiary care centres in Chile, following patients with 22q11.2 deletion. Outcomes Fatality rate and associated factors. Results 59 of 419 patients (14.1%) died during the study period at a median of 3.4 months (range 0 to 32 years of age). Factors associated with death included congenital heart disease (OR 5.27; 95% CI 2.06 to 13.99; p<0.0001), hypocalcaemia (OR 4.27; 95% CI 1.67 to 11.15; p<0.002) and airway malacia (OR 13.37; 95% CI 1.19 to 110.51; p<0.002). Patients with deletions and defects such as tetralogy of Fallot with or without pulmonary atraesia, truncus arteriosus or ventricular septal defect, had a 2.6-fold to 4.6-fold higher death rate compared with nationwide reports for the same types of defects. Conclusions In this cohort, we observed a death rate of 14.1%, implying that one in seven patients with 22q11 deletion died during the study period. Significant associations with cardiac defects, hypocalcaemia and airway malacia were observed. Furthermore, the death risk in patients with 22q11 deletion and cardiac defects exceeded the global figures observed in Chile for infants with structurally similar but apparently isolated anomalies. These observations indicate a need to identify patients who may require specific perioperative management to improve survival.

Palate abnormalities in Chilean patients with chromosome 22q11 microdeletion syndrome.

OBJECTIVE Chromosome 22q11 microdeletion syndrome (del22q11) is the most frequent microdeletion syndrome in humans, with an estimated incidence of 1/4000. It is recognized as a common identifiable cause of cleft palate. We characterized palatal abnormalities in a large cohort of Chilean patients with del22q11. METHODS Patients with the deletion were evaluated by geneticists and speech pathologists, including nasopharyngoscopy when indicated. Comparisons between groups with and without palatal abnormalities were performed using Fishers exact test and Mann-Whitney U test. RESULTS Two hundred and one patients were included in the study. Palate abnormalities were present in 154 patients (76.6%). The most frequent finding was submucous cleft palate (both classic and occult forms) seen in 80 patients (39.8% of the total group). Overt cleft palate or cleft lip/palate was seen in 30 patients (14.9%). Patients without palate abnormalities had significantly greater frequency of congenital heart disease and higher mortality. CONCLUSIONS Our data show a high frequency of palate abnormalities without significant association with congenital heart disease. The most common types of palate defects seen in this series are usually not evident on physical examination and thus require a high index of suspicion and active evaluation through nasopharyngoscopy.

Growth in Chilean infants with chromosome 22q11 microdeletion syndrome.

Chromosome 22q11 microdeletion syndrome has a wide range of clinical manifestations including congenital heart malformations, palatal defects, endocrine abnormalities, immunologic deficits, learning difficulties, and an increased predisposition to psychiatric disease. Short stature and poor weight gain in infancy are common findings and are usually seen in the absence of hormone deficiencies. An increased frequency of obesity has been observed in adolescents and adults. We generated gender‐specific growth curves from 0 to 24 months of age, based on 479 length and 475 weight measurements from 138 Chilean patients with 22q11 deletion. Final adult height and weight on 25 individuals were analyzed. The 10th, 50th, and 90th centile‐smoothed curves for infants were built using the LMS method and compared with World Health Organization Child Growth Standards. The 50th centile for length in the deleted patients was slightly lower than the 10th centile of WHO standards in boys and girls. The same was observed for weight, although a trend toward a gradual increase near 2 years of age was observed, particularly in boys. Average adult height was 152 cm (ranging from 143 to 162 cm) in females, corresponding to the 10th centiles of WHO standards, and 166 cm for males (160–172 cm), at the 20th centile of WHO standards. A third of the adult females and none of the males had body mass index (BMI) greater than 25. The curves should be useful to monitor growth in infants with 22q11 microdeletion syndrome.

Cystic fibrosis in Chilean patients: Analysis of 36 common CFTR gene mutations

BACKGROUND CFTR gene mutations have worldwide differences in prevalence and data on Chilean patients is scarce. METHODS We studied 36 of the most common CFTR mutations in Chilean patients from the CF National Program [Programa Nacional de Fibrosis Quística (PNFQ)] of the Ministry of Health of Chile. RESULTS Two hundred and eighty-nine patients were studied. Fourteen different mutations were identified with an overall allele detection rate of 42.0%. Mutations with frequencies greater than 1% were p.F508del (30.3% of alleles), p.R334W (3.3%), p.G542X (2.4%), c.3849+10Kb C>T (1.7%), and p.R553X (1.2%). A north to south geographical gradient was observed in the overall rate of detection. CONCLUSIONS Southern European CFTR mutations predominate in the Chilean population, but a high percentage of alleles remain unknown. Geographical heterogeneity could be explained in part by admixture. Complementary analyses are necessary to allow for effective genetic counselling and improve cost-effectiveness of screening and diagnostic tests.

Chromosomal microarrays testing in children with developmental disabilities and congenital anomalies

OBJECTIVES Clinical use of microarray-based techniques for the analysis of many developmental disorders has emerged during the last decade. Thus, chromosomal microarray has been positioned as a first-tier test. This study reports the first experience in a Chilean cohort. METHODS Chilean patients with developmental disabilities and congenital anomalies were studied with a high-density microarray (CytoScan™ HD Array, Affymetrix, Inc., Santa Clara, CA, USA). Patients had previous cytogenetic studies with either a normal result or a poorly characterized anomaly. RESULTS This study tested 40 patients selected by two or more criteria, including: major congenital anomalies, facial dysmorphism, developmental delay, and intellectual disability. Copy number variants (CNVs) were found in 72.5% of patients, while a pathogenic CNV was found in 25% of patients and a CNV of uncertain clinical significance was found in 2.5% of patients. CONCLUSION Chromosomal microarray analysis is a useful and powerful tool for diagnosis of developmental diseases, by allowing accurate diagnosis, improving the diagnosis rate, and discovering new etiologies. The higher cost is a limitation for widespread use in this setting.

Proximal Deletion of 6q Overlapping with Toriello-Carey Facial Phenotype: Prenatal Findings, Clinical Course, Differential Diagnosis, and Review

Proximal deletion of 6q is a relatively rare chromosomal abnormality. Reported patients have deletions of different sizes but share partial overlap and present with similar clinical features, and some of them were described prior to the introduction of chromosome microarrays. We describe a male patient with prenatal sonographic findings of nuchal edema, intrauterine growth restriction, renal pelvis dilatation, and oligohydramnios. At birth, facial dysmorphism, retro/micrognathia, a short and wide neck as well as cardiovascular and renal anomalies were noted. His clinical evolution has been marked by failure to thrive, severe developmental delay, and cognitive impairment. The diagnosis of Toriello-Carey syndrome (TCS) was based on his “gestalt.” aCGH identified a de novo proximal deletion of 17 Mb in 6q (6q12q14.3). Deletion 6q13q14 seems to be responsible for the main facial features and should be considered within the differential diagnosis of TCS.

Oculofacial Manifestations of Chromosomal Aberrations

Chromosomal aberrations affect the functionality of certain genes and/or their regulatory elements, leading to congenital anomalies. Congenital ocular and oculofacial anomalies are frequent in this group of patients. This chapter describes the ocular and systemic anomalies resulting from isolated aberrations of chromosome number or structure involving a single chromosome, as detected by karyotype, fluorescence in situ hybridization or chromosomal microarray.