eP455: Fetal ultrasound presentation and neonatal diagnosis of Freeman-Sheldon syndrome in son of previously undiagnosed adult male

ABSTRACT

Background: Freeman-Sheldon syndrome [distal arthrogryposis type 2A (OMIM #193700), DA2A, Freeman-Burian syndrome] is a rare autosomal dominant multiple pterygium syndrome caused by alterations in MYH3. The phenotypic features, particularly of the face, are distinct and easily recognizable, and the diagnosis can be confirmed with molecular gene analysis. Fetal ultrasound imaging may provide important diagnostic clues to facilitate the diagnostic process. Informed consent and parental permission were provided by the parents. Case presentation The infant’s mother presented for a Maternal Fetal Medicine genetic counseling telehealth appointment (due to COVID-19 pandemic restrictions) as a G7P2132, 32-year old female who had insulin-dependent diabetes and thrombocytosis. Her partner was a 24-year old male with a history of hearing loss, a V-shaped palate, and a lower lip cleft. Gestational age was 14 4/7 weeks and the indications were increased nuchal translucency, paternal complex medical history, maternal G6PD heterozygote, and recurrent pregnancy loss. During the genetic counseling session, the following were addressed 1) Maternal heterozygote status for G6PD indicated that if the fetus was male, there was a 50% chance he would be affected with G6PD-deficiency;2) Increased nuchal translucency on fetal ultrasound (US) with measurement at 98th percentile is associated with an increased risk of chromosomal abnormalities, microdeletion/duplications, and Noonan syndrome. The patient reportedly had low risk cell-free DNA but results were not available to the counselor at the time of consult. The option for additional genetic screening and diagnostic testing was declined;3) Three first trimester pregnancy losses with the father of this baby (FOB) were addressed, and parents deferred chromosome analyses at the time;4) Mother shared FOB’s complex history of bilateral sensorineural hearing loss, V-shaped cleft palate, lower lip cleft, and micrognathia. However, father was not present during the telehealth encounter. Mother was counseled regarding the possibility of an autosomal dominant condition with the potential risk to the pregnancy of up to 50%. It was recommended that the FOB have a clinical genetics evaluation, which could potentially provide a specific diagnosis and inform recurrence risk and management guidance. Follow-up MFM genetic counseling telephone visit occurred with the mother at 31 6/7 weeks gestation due to multiple congenital anomalies evident on fetal ultrasound. A 25 week fetal ultrasound revealed hypotelorism and a thickened nuchal translucency. A repeat study at 29 weeks revealed a V-shaped palate with a possible cleft, micrognathia, and midline mandibular cleft. FOB’s history was revisited. It was determined that he had 3 previous “no shows” to Genetics clinic appointments and did not pursue evaluation after the last counseling appointment. Again, it was emphasized that in order to best make a diagnosis for the family, an affected person would need to undergo a thorough evaluation, including medical and family history review, physical examination, and any indicated genetic testing. The parents were comfortable with the likelihood that the baby had the same condition as the father, but variable expressivity and broad range pf phenotypic presentation were explained. Recommendations for postnatal evaluation of the infant and pertinent genetic testing were provided. Consultative Genetics evaluation of the infant at 2 days of age revealed a short, broad forehead with supraorbital fullness leading to a horizontal brow indentation;mask-like facial appearance;hypotelorism;very deep set eyes with blepharophimosis;deep, creased nasal bridge;small, upturned nose with hypoplastic alae and narrow nares;microstomia with pursed lips;glossoptosis;micrognathia;2 deep vertical chin creases;short neck with excess nuchal skin;inverted and wide spaced nipples;clenched hands with 5th digits overlying 4th and 2nd overlying 3rd, bilaterally;bilateral vertical talus;2nd toes longer and overlying rd toes;clinodactyly of 4th and 5th toes bilaterally;and deep gluteal crease with no visible sinus. There were no evident contractures. The father has a complex history with no medical assessments prior to age 18. He reported that he did “not look like anyone else” in his family. He has a diagnosis of autistic spectrum disorder, a submucous cleft, vision issues, hearing loss necessitating a hearing aid on the left, and a history of cholesteatomas and of mastoidectomy. On brief examination, he had a mask-like face, blepharophimosis, left microphthalmia, left esotropia, narrowing of his midface, deep vertical crease on the mandibular region, microstomia, broad great toes, single flexor creases on the thumbs, and contracture of right thumb. Maxillofacial CT of the infant revealed hypoplastic mandibular body, ramus, and condyles bilaterally with micrognathia and retrognathia;hypoplastic maxilla bilaterally;and enophthalmos with retracted appearance of globes in the bony orbits bilaterally. Multiple facial bone abnormalities were seen, including microsomia, micrognathia, retrognathia, orbital hypotelorism and enophthalmos Genetic testing was performed via a custom Whole Exome Slice at GeneDx laboratories and included the MYH3 and TNNI2 genes. Results revealed a heterozygous pathogenic change in MYH3 (c.2015 G>A;p. R6724) consistent with the diagnosis of Freeman-Sheldon syndrome. Conclusion: The presentation of “midline mandibular cleft” on fetal ultrasound was the most specific prenatal finding. This is a very rare fetal finding. Thus, it should prompt further evaluation to assess for true clefting versus ridging or creasing. Additionally, targeted assessment for other findings or clinical clues for Freeman-Sheldon syndrome, such as contractures, “windmill vane” hand, and mouth size, could aid in the differential diagnosis considerations and the diagnostic process. Admittedly, these are position and quality dependent, and are challenging to assess even in ideal situations. The phenotype of the father was immediately recognizable. However, due to COVID-19 pandemic restrictions, prior to the infant’s birth, only telehealth visits were conducted and the father’s participation was by telephone. This limited the ability to narrow the differential diagnosis without visualization of his distinct phenotypic features. Finally, missed opportunities to diagnose the father prior to this pregnancy occurred. Many clinics send “no show” letters to referring providers and patients, as we do. Emphasizing the importance of diagnosis prior to pregnancy for individuals concerned about having a genetic disorder should be considered as part of the information shared in these letters.