Campomelic dysplasia: echographic suspicion in the first trimester of pregnancy and final diagnosis of two cases

Case report: Cystic hygroma accompanied with campomelic dysplasia in the first trimester caused by haploinsufficiency with SOX9 deletion

Introduction: Campomelic dysplasia (CD) is a rare autosomal dominant skeletal malformation syndrome characterized by shortness and bowing of the lower extremities with or without XY sex reversal. Diagnosis using ultrasonography is most often made in the latter half of pregnancy. Intragenic heterozygous mutations in SOX9 are responsible for most cases of CD. CD caused by SOX9 deletion is a rare condition.

Case presentation: We present a single case report of an individual with cystic hygroma accompanied by CD, which was detected by ultrasound in the first trimester. Chromosomal microarray analysis (CMA) was performed to determine copy number variants, whereas whole exome sequencing (WES) was performed to elucidate single-nucleotide variants. Chorionic villus sampling was performed to enable such analyses. Ultimately, CMA detected a 606 kb deletion in the 17q24.3 region with only one protein-coding gene (SOX9). However, no mutation in the SOX9 protein-coding sequence was detected by WES.

Conclusion: When cystic hygroma is detected, prenatal diagnoses for skeletal dysplasia by ultrasound are likely to be confirmed in the first trimester. We propose a comprehensive prenatal diagnostic strategy that combines CMA and WES to diagnose fetuses with cystic hygroma accompanied by skeletal dysplasia.

Diverse Regulation but Conserved Function: SOX9 in Vertebrate Sex Determination

Sex determination occurs early during embryogenesis among vertebrates. It involves the differentiation of the bipotential gonad to ovaries or testes by a fascinating diversity of molecular switches. In most mammals, the switch is SRY (sex determining region Y); in other vertebrates it could be one of a variety of genes including Dmrt1 or dmy. Downstream of the switch gene, SOX9 upregulation is a central event in testes development, controlled by gonad-specific enhancers across the 2 Mb SOX9 locus. SOX9 is a ‘hub’ gene of gonadal development, regulated positively in males and negatively in females. Despite this diversity, SOX9 protein sequence and function among vertebrates remains highly conserved. This article explores the cellular, morphological, and genetic mechanisms initiated by SOX9 for male gonad differentiation.

Agenesis of olfactory bulbs: A forgotten diagnostic indicator of acampomelic campomelic dysplasia

Campomelic dysplasia (CD) and its variant acampomelic campomelic dysplasia (ACD) are caused by SOX9 haploinsufficiency. This gene encodes a transcription factor crucial for embryogenesis and primarily expressed in the olfactory bulbs. The detection of agenesis of olfactory bulbs could help establish a prenatal diagnosis of CD or ACD, although prevalence of this sign remains unknown.

Clinical and molecular characterization of a Brazilian cohort of campomelic dysplasia patients, and identification of seven new SOX9 mutations

Campomelic dysplasia (CD) is an autosomal, dominantly inherited, skeletal abnormality belonging to the subgroup of bent bone dysplasias. In addition to bowed lower limbs, CD typically includes the following: disproportionate short stature, flat face, micrognathia, cleft palate, bell-shaped thorax, and club feet. Up to three quarters of 46, XY individuals may be sex-reversed. Radiological signs include scapular and pubic hypoplasia, narrow iliac wings, spaced ischia, and bowed femora and tibiae. Lethal CD is usually due to heterozygous mutations in SOX9, a major regulator of chondrocytic development. We present a detailed clinical and molecular characterization of nine Brazilian CD patients. Infants were either stillborn (n = 2) or died shortly after birth and presented similar phenotypes. Sex-reversal was observed in one of three chromosomally male patients. Sequencing of SOX9 revealed new heterozygous mutations in seven individuals. Six patients had mutations that resulted in premature transcriptional termination, while one infant had a single-nucleotide substitution at the conserved splice-site acceptor of intron 1. No clear genotype-phenotype correlations were observed. This study highlights the diversity of SOX9 mutations leading to lethal CD, and expands the group of known genetic alterations associated with this skeletal dysplasia.

A novel SOX9 H169Q mutation in a family with overlapping phenotype of mild campomelic dysplasia and small patella syndrome

The phenotypic similarities have been demonstrated between non-lethal campomelic dysplasia (CD) and small patella syndrome (SPS), in which different genetic defects have been identified. We report on a familial case of skeletal dysplasia with overlapping phenotype of mild CD and SPS, including defective ischio-pubic ossification, elongated femoral neck, hypoplastic patellae, and increased space between the first and the second toes (sandal gap). Direct sequencing analysis demonstrated a novel missense mutation (p.H169Q) within the coding region of the SOX9 gene and negative for TBX4 mutations. Functional analysis of the p.H169Q mutant revealed reduced but not fully abolished transactivation capacity of the mutated protein. Retained residual SOX9 function might contribute to an extremely mild CD phenotype in the present cases. © 2013 Wiley Periodicals, Inc.

Enteral Nutrition Related Complications Relevant to Alteration of Formulas in Two Critically Ill Pediatric Patients

The early institution of enteral nutrition is associated with beneficial outcomes and intestinal growth in pediatric patients. However, the number, frequency, and types of unfavorable events occurring with particular formulas are undefined. We experienced unexpected complications in two cases following a change in formula. One case diagnosed with myotubular myopathy experienced highly-increased gastric residuals and watery diarrhea leading to decreased calorie intake and weight loss. The second case with campomelic dysplasia suffered liver dysfunction and fever. In both cases, symptoms developed soon after of the change in formula and improved after resumption of the previous formula. Both cases had undergone tracheostomy and artificial ventilation, and had a history of feeding the same formula for an extended period of time. In chronic care patients such as ours, a change in formula may cause unexpected adverse events; therefore, caution is warranted.

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.