The importance of patient-specific resources for families dealing with prenatal rare diseases.

Rare diseases (RDs) are defined as diseases that affect a low number of the population. Prenatal diagnoses of RDs can add a lot of unique stress for parents. For example, parents who have prenatal diagnoses experience not only grief of expectation, but are forced to become patient advocates with incomplete information as their child is not yet born, and in many cases parents experience a lot of uncertainty. This typically involves seeking support groups and finding pre- and postnatal specialists all which come with mental and financial cost. Here we discuss the importance of targeted patient resources for parents to help alleviate some of their stress. Patient advocacy organizations can be incredibly useful for parents to navigate the complex healthcare system and help mitigate feelings of isolation, especially when parents can talk to others in a similar situation. We collaborated with a patient organization to create a prenatal parent support guide to address how parental needs such as mental well-being and practicing self-care can be met. We hope that resources such as these can help empower those with a pregnancy affected with a RD diagnosis.

Duplicated zebrafish (Danio rerio) inositol phosphatases inpp5ka and inpp5kb diverged in expression pattern and function.

One hurdle in the development of zebrafish models of human disease is the presence of multiple zebrafish orthologs resulting from whole genome duplication in teleosts. Mutations in inositol polyphosphate 5-phosphatase K (INPP5K) lead to a syndrome characterized by variable presentation of intellectual disability, brain abnormalities, cataracts, muscle disease, and short stature. INPP5K is a phosphatase acting at position 5 of phosphoinositides to control their homeostasis and is involved in insulin signaling, cytoskeletal regulation, and protein trafficking. Previously, our group and others have replicated the human phenotypes in zebrafish knockdown models by targeting both INPP5K orthologs inpp5ka and inpp5kb. Here, we show that inpp5ka is the more closely related orthologue to human INPP5K. While both inpp5ka and inpp5kb mRNA expression levels follow a similar trend in the developing head, eyes, and tail, inpp5ka is much more abundantly expressed in these tissues than inpp5kb. In situ hybridization revealed a similar trend, also showing unique localization of inpp5kb in the pineal gland and retina indicating different transcriptional regulation. We also found that inpp5kb has lost its catalytic activity against its preferred substrate, PtdIns(4,5)P2. Since most human mutations are missense changes disrupting phosphatase activity, we propose that loss of inpp5ka alone can be targeted to recapitulate the human presentation. In addition, we show that the function of inpp5kb has diverged from inpp5ka and may play a novel role in the zebrafish.