Expanded carrier screening using next-generation sequencing of 123 Hong Kong Chinese families: a pilot study

INTRODUCTION

To determine the carrier frequency and common mutations of Mendelian variants in Chinese couples using next-generation sequencing (NGS).

METHODS

Preconception expanded carrier testing using NGS was offered to women who attended the subfertility clinic. The test was then offered to the partners of women who had positive screening results. Carrier frequency was calculated, and the results of the NGS panel were compared with those of a target panel.

RESULTS

One hundred twenty-three women and 20 of their partners were screened. Overall, 84 (58.7%) individuals were identified to be carriers of at least one disease, and 68 (47.6%) were carriers after excluding thalassaemias. The most common diseases found were GJB2-related DFNB1 nonsyndromic hearing loss and deafness (1 in 4), alpha-thalassaemia (1 in 7), beta-thalassaemia (1 in 14), 21-hydroxylase deficient congenital adrenal hyperplasia (1 in 13), Pendred's syndrome (1 in 36), Krabbe's disease (1 in 48), and spinal muscular atrophy (1 in 48). Of the 43 identified variants, 29 (67.4%) were not included in the American College of Medical Genetics and Genomics or American College of Obstetrics and Gynecology guidelines. Excluding three couples with alpha-thalassaemia, six at-risk couples were identified.

CONCLUSION

The carrier frequency of the investigated members of the Chinese population was 58.7% overall and 47.6% after excluding thalassaemias. This frequency is higher than previously reported. Expanded carrier screening using NGS should be provided to Chinese people to improve the detection rate of carrier status and allow optimal pregnancy planning.

Expanded newborn metabolic screening programme in Hong Kong: a three-year journey

INTRODUCTION

No universal expanded newborn screening service for inborn errors of metabolism is available in Hong Kong despite its long history in developed western countries and rapid development in neighbouring Asian countries. To increase the local awareness and preparedness, the Centre of Inborn Errors of Metabolism of the Chinese University of Hong Kong started a private inborn errors of metabolism screening programme in July 2013. This study aimed to describe the results and implementation of this screening programme.

METHODS

We retrieved the demographics of the screened newborns and the screening results from July 2013 to July 2016. These data were used to calculate quality metrics such as call-back rate and false-positive rate. Clinical details of true-positive and false-negative cases and their outcomes were described. Finally, the call-back logistics for newborns with positive screening results were reviewed.

RESULTS

During the study period, 30 448 newborns referred from 13 private and public units were screened. Of the samples, 98.3% were collected within 7 days of life. The overall call-back rate was 0.128% (39/30 448) and the false-positive rate was 0.105% (32/30 448). Six neonates were confirmed to have inborn errors of metabolism, including two cases of medium-chain acyl-coenzyme A dehydrogenase deficiency, one case of carnitine-acylcarnitine translocase deficiency, and three milder conditions. One case of maternal carnitine uptake defect was diagnosed. All patients remained asymptomatic at their last follow-up.

CONCLUSION

The Centre of Inborn Errors of Metabolism has established a comprehensive expanded newborn screening programme for selected inborn errors of metabolism. It sets a standard against which the performance of other private newborn screening tests can be compared. Our experience can also serve as a reference for policymakers when they contemplate establishing a government-funded universal expanded newborn screening programme in the future.

Preschool children's difficulty understanding the types of information obtained through the five senses

Two studies explored 3- and 4-year-olds' (N = 60) understanding that the five senses can each lead to different types of knowledge. In Study 1, 40 children engaged in five scenarios in which they could only perform one sensory action to identify the property of an object (e.g., color, scent). After performing the action, children were asked how they found out the property and to show the experimenter how they had found it out. Using a Mr. Potato Head doll, children were also asked to indicate the sensory organ the doll would need to use to identify the property. In Study 2, 20 children presented with five Mr. Potato Head dolls, each sporting only one sensory organ (e.g., a nose), were asked which Mr. Potato Head could find out the property in question. The 3-year-olds performed significantly poorer than the 4-year-olds on all tasks, suggesting a marked transition in children's ability to recognize the origin of their modality-specific knowledge during the time period between 3 and 4 years of age.