Short stature, unusual face, delta phalanx, and abnormal vertebrae and ribs in a girl born to half-siblings

Biallelic variants in KYNU cause a multisystemic syndrome with hand hyperphalangism

Catel-Manzke syndrome is characterized by the combination of Pierre Robin sequence and radial deviation, shortening as well as clinodactyly of the index fingers, due to an accessory ossification center. Mutations in TGDS have been identified as one cause of Catel-Manzke syndrome, but cannot be found as causative in every patient with the clinical diagnosis. We performed a chromosome microarray and/or exome sequencing in three patients with hand hyperphalangism, heart defect, short stature, and mild to severe developmental delay, all of whom were initially given a clinical diagnosis of Catel-Manzke syndrome. In one patient, we detected a large deletion of exons 1-8 and the missense variant c.1282C > T (p.Arg428Trp) in KYNU (NM_003937.2), whereas homozygous missense variants in KYNU were found in the other two patients (c.989G > A (p.Arg330Gln) and c.326G > C (p.Trp109Ser)). Plasma and urine metabolomic analysis of two patients indicated a block along the tryptophan catabolic pathway and urine organic acid analysis showed excretion of xanthurenic acid. Biallelic loss-of-function mutations in KYNU were recently described as a cause of NAD deficiency with vertebral, cardiac, renal and limb defects; however, no hand hyperphalangism was described in those patients, and Catel-Manzke syndrome was not discussed as a differential diagnosis. In conclusion, we present unrelated patients identified with biallelic variants in KYNU leading to kynureninase deficiency and xanthurenic aciduria as a very likely cause of their hyperphalangism, heart defect, short stature, and developmental delay. We suggest performance of urine organic acid analysis in patients with suspected Catel-Manzke syndrome, particularly in those with cardiac or vertebral defects or without mutations in TGDS.

Long-term follow-up on fetuses with isolated sonographic finding of short long bones: a cohort study

PURPOSE

To evaluate the long-term outcome of fetuses with a diagnosis of isolated short long bones.

METHODS

A retrospective review was conducted of all cases diagnosed with short long bones above 20 weeks of gestation during 2010-2017 in a single tertiary center. Exclusion criteria included abnormal sonographic findings other than short long bones, suspected genetic syndromes, chromosomal abnormalities, and abnormal Doppler flow indices. Follow-up was carried out by telephone questionnaire.

RESULTS

During the study period, 54 (24.32%) women met inclusion criteria. Mean gestational age at delivery was 38.05 years (± 2.42 SD). Mean birth weight was 12-19th percentile according to the local fetal growth charts [2645 g (± 684 SD) 95% CI 2173-2980]. Median time for post-natal follow-up was 9.3 years (IQR 6.6-10.75). Growth below the 10th percentile was demonstrated in 27 (50%) children. 11 (20.37%) children were followed up by endocrinological clinics, of them 7 (12.96%) were treated with growth hormone. Three (5.6%) of the children were diagnosed with attention deficit hyperactivity disorder, an incidence that is considered lower than that of the general population (± 9%).

CONCLUSIONS

Prenatal fetal isolated short long bones diagnosed during the late second and third trimester is associated with short stature. No neurodevelopmental impact was observed in our study group.