Role of genetic investigation in the diagnosis of short stature in a cohort of Italian children.

BACKGROUND: Short stature (SS) is defined as height more than 2 standard deviations below the mean for age and sex. Hypothyroidism, celiac disease, growth hormone deficiency, hormonal abnormalities, and genetic conditions are among its causes. A wide range of conditions often due to largely unknown genetic variants can elude conventional diagnostic workup. AIM: We used next-generation sequencing (NGS) to better understand the etiology of SS in a cohort of Italian children. PATIENTS AND METHODS: The study sample was 125 children with SS of unknown origin referred to our Institute between 2015 and 2021. All had undergone complete auxological and hormonal investigations to exclude common causes of SS. Genetic analysis was performed using a NGS panel of 104 genes. Clinical data were reviewed to clarify the pathogenicity of the variants detected. RESULTS: In this cohort, 43 potentially causing variants were identified in 38 children. A syndromic genetic condition was diagnosed in 7: Noonan syndrome in 3, Leri-Weill syndrome in 3, and hypochondroplasia in 1. Moreover, 8 benign variants and other 37 like benign variants were found. In 88 children, 179 variants of uncertain significance (VUS) were identified. No variant was found in 16 children. CONCLUSION: Genetic analysis is a useful tool in the diagnostic workup of patients with SS, in adapting management and treatment, and in identifying syndromes with mild atypical clinical features. The role of VUS should not be underestimated, particularly when multiple VUS with possible mutual worsening effects are present in the same child.

Phenotype of five cases of prenatally diagnosed campomelic dysplasia harboring novel mutations of the SOX9 gene.

OBJECTIVES: Campomelic dysplasia is a rare congenital skeletal disorder characterized by bowing of the long bones and a variety of other skeletal and extraskeletal defects, many of which can now be identified prenatally using advanced ultrasound equipment. The disorder is caused by mutations in SRY-box 9 (SOX9), a gene that is abundantly expressed in chondrocytes as well as in other tissues. However, the correlation between genotype and phenotype is still unclear. We report five cases of prenatally detected campomelic dysplasia in which the diagnosis was confirmed by molecular analysis. METHODS: Ultrasound examinations were performed between 12 and 32 weeks. Standard fetal biometric measurements were obtained. Fetal sex was determined sonographically and confirmed by chromosomal analysis. Genomic DNA was obtained in four cases before termination of pregnancy from chorionic villi or amniocytes and in one case postnatally from peripheral blood. RESULTS: Skeletal dysplasia, most often limb shortening and bowed femora, was observed in one case in the first trimester, in three cases in the second trimester and in one case, presenting late for antenatal care, in the third trimester. Four of the pregnancies were terminated and one was carried to term. Postmortem/postnatal physical and radiographic examinations confirmed the presence of anomalies characteristic of campomelic dysplasia. A de novo mutation in the SOX9 gene was detected in all four cases that underwent termination. The father of the proband in the case that went to term was a carrier of a somatic mosaic mutation without clinical or radiographic signs of campomelic dysplasia. CONCLUSIONS: It is likely that the integrated expertise of ultrasonographers, obstetricians, pediatricians and clinical geneticists will markedly improve the likelihood of accurate prenatal clinical diagnoses of campomelic dysplasia. This will, in turn, encourage more specific molecular testing and facilitate comprehensive genetic counseling.

The Italian National External quality assessment program in molecular genetic testing: results of the VII round (2010-2011).

Since 2001 the Istituto Superiore di Sanità established a quality assurance programme for molecular genetic testing that covers four pathologies: Cystic Fibrosis (CF), Beta Thalassemia (BT), Fragile X Syndrome (FX), and Familial Adenomatous Polyposis Coli (APC). Since 2009 this activity is an institutional activity and participation is open to both public and private laboratories. Seven rounds have been performed until now and the eighth is in progress. Laboratories receive 4 DNA samples with mock clinical indications. They analyze the samples using their routine procedures. A panel of assessors review the raw data and the reports; all data are managed through a web utility. In 2010 the number of participants was 43, 17, 15, 5 for CF, BT, FX, APC schemes respectively. Genotyping results were correct in 96%, 98.5%, 100%, and 100% of CF, BT, FX, and APC samples, respectively. Interpretation was correct in 74%, 91%, 88%, and 60% of CF, BT, FX, and APC reports, respectively; however in most of them it was not complete but a referral to genetic counseling was given. Reports were satisfactory in more than 60% of samples in all schemes. This work presents the 2010 results in detail comparing our data with those from other European schemes.