Manifestations of thrombospondin type-1 domain-containing protein 1 gene mutation in an extremely premature infant with nonimmune hydrops fetalis.

Homozygous variants of the thrombospondin type-1 domain-containing 1 (THSD1) gene have recently been associated with nonimmune hydrops fetalis (NIHF; OMIM 236750) in infants, as well as with congenital heart disease, hemangiomas, prematurity, and embryonic lethality. Here, we report the first case of a biallelic variant of THSD1 in an extremely premature infant (25 weeks) who suffered from NIHF (eventually resolved) and other manifestations of the THSD1 variant, such as congenital heart disease and hemangiomas. Her prematurity was complicated by pulmonary hypertension and chronic lung disease. This case indicates that biallelic homozygous variants of THSD1 are among the likely causes of NIHF. Information from this case report will aid in determining the prognosis of NIHF caused by such variants in premature infants.