Nicotinamide adenine dinucleotide (NAD) is an essential coenzyme involved in over 400 cellular reactions. During embryogenesis, mammals synthesize NAD de novo from dietary l ‐tryptophan via the kynurenine pathway. Biallelic, inactivating variants in three genes encoding enzymes of this biosynthesis pathway (KYNU, HAAO, and NADSYN1) disrupt NAD synthesis and have been identified in patients with multiple malformations of the heart, kidney, vertebrae, and limbs; these patients have Congenital NAD Deficiency Disorder HAAO and four families with biallelic variants in KYNU. These patients present similarly with multiple malformations of the heart, kidney, vertebrae, and limbs, of variable severity. We show that each variant identified in these patients results in loss‐of‐function, revealed by a significant reduction in NAD levels via yeast genetic complementation assays. For the first time, missense mutations are identified as a cause of malformation and shown to disrupt enzyme function. These missense and frameshift variants cause moderate to severe NAD deficiency in yeast, analogous to insufficient synthesized NAD in patients. We hereby expand the genotypic and corresponding phenotypic spectrum of Congenital NAD Deficiency Disorder.

Consanguinity, the union between two individuals who are related as second cousins or closer, is a long‐standing and respected tradition in many communities. Although there are social and economic benefits of consanguineous unions, offspring are at increased risk of having an inherited genetic condition or congenital anomaly. Genetic counseling services for consanguinity are available to couples at many centers. However, little is known about patient expectations of and experiences with genetic counseling for this indication, or their perspectives on genetic screening relevant to family planning, such as expanded carrier screening (ECS). This exploratory qualitative study involved interviews with 13 individuals who had recently received preconception or prenatal genetic counseling for consanguinity at a single center. We sought to gain insight into their expectations for the genetic counseling session, experiences discussing family history and reproductive risks with the genetic counselor, and views on ECS. Interview transcripts were analyzed using an interpretive descriptive approach. Data analysis revealed three main themes: (a) anticipation balances apprehension before the appointment; (b) genetic counseling reduces anxiety and empowers; and (c) the need for wider information dissemination about consanguinity‐related risks and genetic services. Our findings support the personal utility of genetic counseling for consanguinity and demonstrate the need for increased visibility and access to genetics information, counseling, and testing relevant to this patient population.

Prenatal diagnosis of CDPX2 is difficult because of marked phenotypic variation. Epiphyseal stippling, ectopic paravertebral calcifications, asymmetric shortening of long bones and dysmorphic flattened facies are crucial for prenatal diagnosis. DNA analysis of the CDPX2 gene and biochemical determination of the serum 8(9)-cholestenol level are important for diagnosis, especially if future pregnancies are planned.

Intrachromosomal insertions are rare and difficult to diagnose. However, making the correct diagnosis is critical for genetic risk assessment, and prenatal and preimplantation genetic diagnosis outcomes. We present a case of preimplantation genetic diagnosis (PGD) using array comparative genomic hybridization (aCGH) following trophectoderm biopsy of embryos created after in vitro fertilization for a carrier of an intrachromosomal insertion on chromosome 1 [46,XX, ins (1)(q44q23q32.1)]. The PGD analysis of 6 blastocysts demonstrated 67% unbalanced embryos. No pregnancy was achieved after the transfer of 2 euploid embryos. To the best of our knowledge, this is the first reported case of PGD using aCGH following trophectoderm biopsy for a carrier of an intrachromosomal insertion.

Small supernumerary marker chromosomes (sSMC) can form small supernumerary ring chromosomes (sSRC). Loss of parentally inherited sSRC containing vital gene content may cause an “unbalanced” karyotype and fetal microdeletion syndromes. Rarely, sSRC with neocentromere can be inherited, leading to a “balanced” karyotype, which can be diagnosed with preimplantation genetic testing.