Hematology Clinic-Internal Medicine Dept. "A. Cardarelli" Hospital, Campobasso, Italy.
Thrombosis and Haemostasis Unit, Fondazione I.R.C.C.S. "Casa Sollievo della Sofferenza", Viale Cappuccini, S. Giovanni Rotondo, 71013, Foggia, Italy.
BMC Pregnancy Childbirth. 2020 Dec 11;20(1):772. doi: 10.1186/s12884-020-03437-2.
May-Hegglin anomaly is an autosomal dominant inherited condition, characterized by thrombocytopenia, giant platelets and Dohle-like bodies. Incidence is unknown and affected individuals can show from mild to moderate-severe haemorrhagic symptoms. The cyst of cavum veli interpositi (a virtual space filled with fluid within the third ventricle) is rarely reported in the foetal period. Furthermore, it is unclear whether isolated cavum veli interpositi cysts are a normal variant or developmental malformations. The simultaneous presence of these two anomalies was never described.
We describe a very rare case of a twin monochorionic pregnancy in a woman with the May-Hegglin anomaly, whose foetuses carried cavum veli interpositi cysts. Since childhood, our patient had shown macro-thrombocytopenia, deafness and bleeding (epistaxis and menorrhagia), but she was misdiagnosed until the age of 30 years when our Centre identified a de novo allelic variant in the gene MYH9 coding for the non-muscle myosin heavy chain IIa. Our patient bled neither during the pregnancy, nor in the peripartum period. Children are now eight-months-old and have never bled, although both inherited the MYH9 variant and have thrombocytopenia with giant platelets. Furthermore, none of them developed psychomotor disorders.
To the best of our knowledge, this is the sixth case of twin pregnancy in a woman carrying May-Hegglin anomaly and the first one with cavum veli interpositi cysts in the neonates. We speculate that MYH9 could have, at least in part, played a role in the development of both conditions, as this gene has a pleiotropic effect.
巨大血小板综合征是一种常染色体显性遗传性疾病，其特征为血小板减少、巨大血小板和杜勒小体。该病的发病率未知，受影响的个体可表现出从轻度到中度-重度出血症状。在胎儿期，腔静脉间腔（第三脑室内部充满液体的虚拟空间）的囊肿很少见报道。此外，孤立的腔静脉间腔囊肿是否为正常变异或发育畸形尚不清楚。同时存在这两种异常的情况从未被描述过。
我们描述了一例极为罕见的单绒毛膜双胞胎妊娠合并巨大血小板综合征病例，其胎儿存在腔静脉间腔囊肿。自童年起，我们的患者就表现出巨血小板减少症、耳聋和出血（鼻出血和月经过多），但直到 30 岁时我们中心在编码非肌肉肌球蛋白重链 IIa 的基因 MYH9 中发现了一个新的等位基因变异，才被确诊。我们的患者在怀孕期间和围产期都没有出血。现在孩子已经 8 个月大了，从未出血过，尽管他们都遗传了 MYH9 变异，且都存在血小板减少伴巨大血小板，但他们都没有出现精神运动障碍。
据我们所知，这是第六例患有巨大血小板综合征的女性的双胞胎妊娠病例，也是首例在新生儿中出现腔静脉间腔囊肿的病例。我们推测，MYH9 至少在一定程度上参与了这两种疾病的发生，因为该基因具有多效性。
