Long-term clinical observation of patients with heterozygous KIF1A variants.

KIF1A-related disorders (KRDs) encompass recessive and dominant variants with wide clinical variability. Recent genetic investigations have expanded the clinical phenotypes of heterozygous KIF1A variants. However, there have been a few long-term observational studies of patients with heterozygous KIF1A variants. A retrospective chart review of consecutive patients diagnosed with spastic paraplegia at Miyagi Children's Hospital from 2016 to 2020 identified six patients with heterozygous KIF1A variants. To understand the long-term changes in clinical symptoms, we examined these patients in terms of their characteristics, clinical symptoms, results of electrophysiological and neuroimaging studies, and genetic testing. The median follow-up period was 30 years (4-44 years). This long-term observational study showed that early developmental delay and equinus gait, or unsteady gait, are the first signs of disease onset, appearing with the commencement of independent walking. In addition, later age-related progression was observed in spastic paraplegia, and the appearance of axonal neuropathy and reduced visual acuity were characteristic features of the late disease phenotype. Brain imaging showed age-related progression of cerebellar atrophy and the appearance of hyperintensity of optic radiation on T2WI and FLAIR imaging. Long-term follow-up revealed a pattern of steady progression and a variety of clinical symptoms, including spastic paraplegia, peripheral neuropathy, reduced visual acuity, and some degree of cerebellar ataxia. Clinical variability between patients was observed to some extent, and therefore, further studies are required to determine the phenotype-genotype correlation.

A deletion variant in LMX1B causing nail-patella syndrome in Japanese twins.

Nail-patella syndrome (NPS) is a hereditary disease caused by pathogenic variants in LMX1B and characterized by nail, limb, and renal symptoms. This study revealed a likely pathogenic LMX1B variant, NM_002316.4: c.723_726delinsC (p.Ser242del), in Japanese twins with clubfoot. The patients' mother, who shared this variant, developed proteinuria after delivery. p.Ser242del is located in the homeodomain of the protein, in which variants that cause renal disease tend to cluster. Our findings highlight p.Ser242del as a likely pathogenic variant, expanding our knowledge of NPS.

Severe Early-Onset Vitamin K Deficiency Bleeding in a Neonate Born to a Mother with Crohn's Disease in Clinical Remission: A Case Report.

Vitamin K deficiency bleeding (VKDB) in neonates is a significant disorder that causes skin, gastrointestinal, and intracranial hemorrhaging. Early-onset VKDB occurs within 24 hours of birth, and its prognosis is poor due to severe hemorrhage. The causes of early-onset VKDB include maternal intake of warfarin and anticoagulants, and maternal vitamin K deficiency. We report the case of a neonate with early-onset VKDB born to a mother with Crohn's disease. The neonate developed severe cerebellar hemorrhage on the day of birth and subsequent noncommunicating hydrocephalus requiring a ventriculoperitoneal shunt. The mother had a 14-year history of Crohn's disease and short bowel owing to intestinal resection. She was in complete remission during pregnancy according to the Crohn's Disease Activity Index. Endoscopic examination performed shortly before pregnancy revealed inflammatory findings in the residual small intestine. Her blood tests at delivery showed an elevated prothrombin induced by vitamin K deficiency or antagonist II (PIVKA-II) level of 26,900 mAU/mL. A definitive protocol to prevent early-onset VKDB in mothers with Crohn's disease complicated by a short bowel is lacking. Administering vitamin K to mothers with elevated PIVKA-II levels before delivery may help prevent early-onset VKDB.