Elena Mansilla

Background: Fetus in fetu (FIF) is an exceptionally rare congenital anomaly, often difficult to distinguish from fetiform teratoma. We report a genetically proven retroperitoneal FIF in a neonate and review the literature. Case Presentation: A term female infant presented with a prenatal retroperitoneal cystic mass. Postnatal imaging demonstrated calcifications suggestive of vertebral structures, although teratoma remained in the differential diagnosis. Serum tumor markers showed markedly elevated alpha-fetoprotein (AFP) and normal beta-human chorionic gonadotropin (β-hCG). Complete excision at 2 months revealed a sac containing a fetiform mass with scalp. Histology identified only mature tissues (glial tissue, choroid plexus, retinal pigment epithelium, dental alveoli, lamellar bone with hematopoiesis), without immature elements. Genetic testing by quantitative fluorescent PCR confirmed a diallelic profile identical to the host (46,XX), establishing the diagnosis of FIF. AFP normalized within 6 months, and the infant remained asymptomatic at 18 months. Discussion: Imaging, particularly CT and MRI, is essential for diagnosis and surgical planning, though distinction from teratoma can remain uncertain. Histology may suggest FIF but is not always definitive. Genetic identity between host and mass provides diagnostic certainty, resolving the long-standing controversy with fetiform teratoma. Our review confirms approximately 250 cases reported to date, with ~80% retroperitoneal and excellent outcomes following complete resection. Conclusion: FIF should be considered in neonates with retroperitoneal masses. Genetic analysis is crucial when pathology is inconclusive, ensuring diagnostic accuracy and guiding follow-up.

Background/Objectives: Wolf–Hirschhorn syndrome (WHS; OMIM #194190) is a rare neurodevelopmental disorder, caused by deletions in the distal short arm of chromosome 4. It is characterized by developmental delay, epilepsy, intellectual disability, and distinctive facial dysmorphism. Clinical presentation varies widely, complicating prognosis and individualized care. Methods: We assembled a cohort of 140 individuals with genetically confirmed WHS from Spain and Latin-America, and developed and validated a multidimensional, Clinician-Reported Outcome Assessment (ClinRO) based on the Global Functional Assessment of the Patient (GFAP), derived from standardized clinical questionnaires and weighted by HPO (Human Phenotype Ontology) term frequencies. The GFAP score quantitatively captures key functional domains in WHS, including neurodevelopment, epilepsy, comorbidities, and age-corrected developmental milestones (selected based on clinical experience and disease burden). Results: Higher GFAP scores are associated with worse clinical outcomes. GFAP showed strong correlations with deletion size, presence of additional genomic rearrangements, sex, and epilepsy severity. Ward’s clustering and discriminant analyses confirmed GFAP’s discriminative power, classifying over 90% of patients into clinically meaningful groups with different prognoses. Conclusions: Our findings support GFAP as a robust, WHS-specific ClinRO that may aid in stratification, prognosis, and clinical management. This tool may also serve future interventional studies as a standardized outcome measure. Beyond its clinical utility, GFAP also revealed substantial social implications. This underscores the broader socioeconomic burden of WHS and the potential value of GFAP in identifying high-support families that may benefit from targeted resources and services.

The 22q11.2 region is highly susceptible to genomic rearrangements leading to multiple genomic disorders, including 22q11.2 microdeletion syndrome (22q11.2 DS) (MIM# 188400), 22q11.2 microduplication syndrome (MIM# 608363), supernumerary der(22)t(11;22) syndrome (also known as Emanuel Syndrome; MIM# 609029), and Cat Eye Syndrome (MIM# 115470). In this study, we present data on causes of mortality, average age of death, and the existing associated risk factors in patients with 22q11.2 rearrangements. Our cohort included 223 patients (120 males and 103 females) with confirmed diagnoses of 22q11.2 rearrangements diagnosed through molecular techniques (FISH, MLPA, and CMA). Relatives from patients who have been molecularly confirmed with 22q11.2 rearrangements have also been added to the study, regardless of the presence or absence of symptoms. Of these 223 individuals, 21 (9.4%) died. Deceased patients’ rearrangements include 19 microdeletions, 1 microduplication, and 1 patient with a marker chromosome. The median age of death was 3 months and 18 days (ranging from 3 days to 34 years). There were 17 patients who died at pediatric age (80.95%), 3 died at adult age (14.28%), and for 1 of whom, the age of death is unknown (4.76%). Eighteen patients were White Mediterranean (European non-Finnish) (85.71%) whereas three were Amerindian (South American) (14.28%). Mortality from cardiac causes accounted for 71.42%. The second most frequent cause of death was sepsis in two patients (9.52%). One patient died from respiratory failure (4.76%) and one from renal failure (4.76%). Information regarding the cause of death was not available in two patients (9.52%). Most patients who died were diagnosed within the first week of life, the majority on the first day. This study adds additional information on mortality in one of the largest cohorts of patients with 22q11.2 rearrangements in more than 30 years of follow-up.

Introduction: This study aimed to evaluate the occurrence of clinically relevant (sub)microscopic chromosomal aberrations in fetuses with the nuchal translucency (NT) range from 3.0 to 3.4 mm, which would be potentially missed by cfDNA testing. Methods: A retrospective data analysis of 271 fetuses with NT between 3.0 and 3.4 mm and increased first trimester combined test (CT) risk in five cohorts of pregnant women referred for invasive testing and chromosomal microarray was performed. Results: A chromosomal aberration was identified in 18.8% fetuses (1:5; 51/271). In 15% (41/271) of cases, trisomy 21, 18, or 13 were found. In 0.7% (2/271) of cases, sex chromosome aneuploidy was found. In 1.1% (3/271) of cases, CNV >10 Mb was detected, which would potentially also be detected by genome-wide cfDNA testing. The residual risk for missing a submicroscopic chromosome aberration in the presented cohorts is 1.8% (1:54; 5/271). Conclusion: Our results indicate that a significant number of fetuses with increased CT risk and presenting NT of 3.0–3.4 mm carry a clinically relevant chromosomal abnormality other than common trisomy. Invasive testing should be offered, and counseling on NIPT should include the test limitations that may result in NIPT false-negative results in a substantial percentage of fetuses.

Autism spectrum disorders (ASD) comprise a group of neurodevelopmental disorders (NDD) characterized by deficits in communication and social interaction, as well as repetitive and restrictive behaviors, etc. The genetic implications of ASD have been widely documented, and numerous genes have been associated with it. The use of chromosomal microarray analysis (CMA) has proven to be a rapid and effective method for detecting both small and large deletions and duplications associated with ASD. In this article, we present the implementation of CMA as a first-tier test in our clinical laboratory for patients with primary ASD over a prospective period of four years. The cohort was composed of 212 individuals over 3 years of age, who met DSM-5 diagnostic criteria for ASD. The use of a customized array-CGH (comparative genomic hybridization) design (KaryoArray^®) found 99 individuals (45.20%) with copy number variants (CNVs); 34 of them carried deletions (34.34%) and 65 duplications (65.65%). A total of 28 of 212 patients had pathogenic or likely pathogenic CNVs, representing approximately 13% of the cohort. In turn, 28 out of 212 (approximately 12%) had variants of uncertain clinical significance (VUS). Our findings involve clinically significant CNVs, known to cause ASD (syndromic and non-syndromic), and other CNVs previously related to other comorbidities such as epilepsy or intellectual disability (ID). Lastly, we observed new rearrangements that will enhance the information available and the collection of genes associated with this disorder. Our data also highlight that CMA could be very useful in diagnosing patients with essential/primary autism, and demonstrate the existence of substantial genetic and clinical heterogeneity in non-syndromic ASD individuals, underscoring the continued challenge for genetic laboratories in terms of its molecular diagnosis.

Phelan-McDermid syndrome (PMS, OMIM# 606232) results from either different rearrangements at the distal region of the long arm of chromosome 22 (22q13.3) or pathogenic sequence variants in the SHANK3 gene. SHANK3 codes for a structural protein that plays a central role in the formation of the postsynaptic terminals and the maintenance of synaptic structures. Clinically, patients with PMS often present with global developmental delay, absent or severely delayed speech, neonatal hypotonia, minor dysmorphic features, and autism spectrum disorders (ASD), among other findings. Here, we describe a cohort of 210 patients with genetically confirmed PMS. We observed multiple variant types, including a significant number of small deletions (SHANK3 sequence variants (21 cases). We also detected multiple types of rearrangements among microdeletion cases, including a significant number with post-zygotic mosaicism (9.0%, 17/189), ring chromosome 22 (10.6%, 20/189), unbalanced translocations (de novo or inherited, 6.4%), and additional rearrangements at 22q13 (6.3%, 12/189) as well as other copy number variations in other chromosomes, unrelated to 22q deletions (14.8%, 28/189). We compared the clinical and genetic characteristics among patients with different sizes of deletions and with SHANK3 variants. Our findings suggest that SHANK3 plays an important role in this syndrome but is probably not uniquely responsible for all the spectrum features in PMS. We emphasize that only an adequate combination of different molecular and cytogenetic approaches allows an accurate genetic diagnosis in PMS patients. Thus, a diagnostic algorithm is proposed.

Objective: Prenatal diagnoses of microdeletion syndromes without ultrasound findings in the first and second trimester are always difficult. The objective of this study is to report the prenatal ultrasound findings in four foetuses diagnosed with 17q21.31 microdeletions (Koolen‐de Vries syndrome) using chromosomal microarrays (CMA).Patients and Methods: We present four foetuses with 17q21.31 microdeletion. All showed CNS anomalies in the third trimester, three had ventriculomegaly, and one hypogenesis of corpus callosum at 31 weeks of pregnancy.Results: Array‐SNPs and CGH‐array were performed on uncultured amniocytes and peripheral blood revealing a 17q21.31 microdeletion.Conclusions: Prenatal CNS anomalies (mainly ventriculomegaly) at third trimester, in spite of isolate, should be considered a prenatal ultrasound marker of this syndrome. This kind of malformations raise the possibility of an underlying genetic conditions including 17q21.31 microdeletion; thus, CMA should be taken into consideration when offering prenatal genetic counselling.

Inverted duplication 8p associated with deletion of the short arms of chromosome 8 (invdupdel[8p]) is a relatively uncommon complex chromosomal rearrangement, with an estimated incidence of 1 in 10,000–30,000 live borns. The chromosomal rearrangement consists of a deletion of the telomeric region (8p23‐pter) and an inverted duplication of the 8p11.2–p22 region. Clinical manifestations of this disorder include severe to moderate intellectual disability and characteristic facial features. In most cases, there are also CNS associated malformations and congenital heart defects. In this work, we present the cytogenetic and molecular characterization of seven children with invdupdel(8p) rearrangements. Subsequently, we have carried out genotype–phenotype correlations in these seven patients. The majority of our patients carry a similar deletion but different size of duplications; the latter probably explaining the phenotypic variability among them. We recommend that complete clinical evaluation and detailed chromosomal microarray studies should be undertaken, enabling appropriate genetic counseling.

We and others have previously reported that familial cytogenetic studies in apparently de novo genomic imbalances may reveal complex or uncommon inheritance mechanisms. A familial, combined genomic and cytogenetic approach was systematically applied to the parents of all patients with unbalanced genome copy number changes. Discordant array-CGH and FISH results in the mother of a child with a prenatally detected 16p13.11 interstitial microduplication disclosed a balanced uncommon rearrangement in this chromosomal region. Further dosage and haplotype familial studies revealed that both the maternal grandfather and uncle had also the same 16p duplication as the proband. Genomic compensation observed in the mother probably occurred as a consequence of interchromosomal postzygotic nonallelic homologous recombination. We emphasize that such a dualistic strategy is essential for the full characterization of genomic rearrangements as well as for appropriate genetic counseling.