Diagnosis of Menke-Hennekam syndrome by prenatal whole exome sequencing and review of prenatal signs.

INTRODUCTION: CREBBP truncating mutations and deletions are responsible for the well-known Rubinstein-Taybi syndrome. Recently, a new, distinct CREBBP-linked syndrome has been described: missense mutations located at the 3' end of exon 30 and the 5' portion of exon 31 induce Menke-Hennekam syndrome. Patients with this syndrome present a recognizable facial dysmorphism, intellectual disability of variable severity, microcephaly, short stature, autism, epilepsy, visual and hearing impairments, feeding problems, upper airway infections, scoliosis, and/or kyphosis. To date, all diagnoses were made postnatally. METHOD AND CASE REPORT: Trio-whole exome sequencing (WES) was performed in a fetus showing increased nuchal translucency persistence and aorta abnormalities at 28 weeks of gestation (WG). RESULTS: WES revealed a CREBBP de novo missense mutation (c.5602C>T; p.Arg1868Trp) in exon 31, previously reported as the cause of Menke-Hennekam syndrome. Termination of pregnancy was performed at 32 WG. We further reviewed the prenatal signs of Menke-Hennekam syndrome already reported. Among the 35 patients reported and diagnosed postnatally up to this day, 15 presented recognizable prenatal signs, the most frequent being intra-uterine growth retardation, brain, and cardiovascular anomalies. CONCLUSION: Menke-Hennekam is a rare syndrome with unspecific, heterogeneous, and inconstant prenatal symptoms occurring most frequently with the c.5602C>T, p.(Arg1868Trp) mutation. Therefore, the prenatal diagnosis of Menke-Hennekam syndrome is only possible by molecular investigation. Moreover, this case report and review reinforce the importance of performing prenatal WES when unspecific signs are present on imaging.

Two novel variations p.(Ser1275Thr) and p.(Ser1275Arg) in FLT4 causing prenatal hereditary lymphedema type 1.

BACKGROUND: Hereditary lymphedema 1 is a rare congenital condition, characterized by the development of chronic swelling in body parts. It is highly variable in expression and age of onset with different presentations: from feet edema to hydrops fetalis. This affection is genetically heterogeneous with autosomal dominant inheritance and incomplete penetrance due to a mutation in the FLT4 gene in most cases. CASES: In our study, we report on two fetuses harboring congenital lymphedema with FLT4 variation and review the prenatal confirmed ones of the literatures. Our cases were selected within fetuses explored by exome sequencing in a diagnosis setting. Prenatal ultrasonography showed hydrops fetalis in one case and an increased nuchal translucency with hydrothorax in the other. Comparative genomic hybridization array on amniocentesis was normal in both cases. Exome sequencing identified a variation p.(Ser1275Thr) and p.(Ser1275Arg) in fetus 1 and fetus 2 in the FLT4 gene, respectively. A de novo mutation at the same codon was reported in prenatal literature suggesting possible genotype phenotype correlation. CONCLUSION: Cystic hygroma/hydrops fetalis are possible manifestations of several disorders. This study illustrates how the integration of exome sequencing in prenatal clinical practice can facilitate the diagnosis and genetic counseling of heterogeneous developmental affections.